Causes of Heat rash
Heat rash Causes: Book Excerpts
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Pruritus:
Differential Diagnosis
(In A Page: Pediatric Signs and Symptoms)
- Urticaria
–Hypersensitivity reaction causing edema via mast cell/basophil release of histamine, kinins, prostaglandins, and serotonin, mostly IgE-mediated
–Hives; subcutaneous and mucous membranes
–Angioedema: Most cases acute (resolving within 48 hours); chronic >6 weeks
–Anaphylaxis: May be life-threatening
-
Atopic dermatitis
–Incidence 2–10%; often begins in infancy
–Most cases improve with age
–Frequent remissions/exacerbations
–Increased risk of infection (herpes, eczema
herpeticum; staph, strep)
–Can be exercise-induced
-
Xerosis (dry skin)
–Idiopathic or due to excessive bathing, low humidity, etc.
-
Tinea (dermatophytoses, “ringworm”)
–Fungal infection (Trichophyton,
Microsporum, Epidermophyton)
–Scalp (tinea capitis), face, trunk, extremities
(t. corporis), feet (t. pedis)
–complications: superinfection and kerion
-
Contact dermatitis
–Allergens (poison ivy, cosmetics, dyes,
drugs, foods, jewelry/nickel, animals)
–Irritants (soap, chemicals, wool, fiberglass)
-
Scarlet fever (group A strep): “Sandpaper rash,” incubation period 1–7 days; age 5–15 years, 15–20% colonized (oropharyngeal)
-
Herpes: Varicella, zoster, herpes simplex
-
Lice (pediculosis): Head or pubic area
-
Mites (scabies [Sarcoptes scabiei])
-
Pinworms (Enterobius vermicularis)
-
Cholestasis (TPN, biliary atresia)
-
Erythema multiforme (“bull's eye rash”): Stevens-Johnson syndrome
-
Drug-induced: Opiates, barbiturates, isoniazid, phenothiazines, erythromycin
-
Systemic diseases: Malignancies, renal failure, mastocytosis, SLE, JRA, hypo- and hyperthyroidism, DM
-
Prurigo gestationis
-
Parasites (“swimmer itch,” trematodes)
-
Chronic skin diseases (psoriasis)
» READ BOOK EXCERPT ONLINE »
Source: In A Page: Pediatric Signs and Symptoms, 2007
Pruritus:
Medical causes
(Handbook of Signs & Symptoms (Third Edition))
Anemia (iron deficiency)
Iron deficiency anemia occasionally produces pruritus. Initially asymptomatic, anemia can later cause exertional dyspnea, fatigue, listlessness, pallor, irritability, a headache, tachycardia, poor muscle tone and, possibly, murmurs. Chronic anemia causes spoon-shaped (koilonychia) and brittle nails (cheilosis), cracked mouth corners, a smooth tongue (glossitis), and dysphagia.
Anthrax (cutaneous)
Anthrax is an acute infectious disease caused by the gram-positive, spore-forming bacterium Bacillus anthracis. It can occur in humans who are exposed to infected animals, tissue from infected animals, or biological warfare. Cutaneous anthrax occurs when the bacterium enters a cut or an abrasion on the skin. The infection begins as a small, painless or pruritic macular or papular lesion resembling an insect bite. Within 1 to 2 days, it develops into a vesicle and then a painless ulcer with a characteristic black, necrotic center. Lymphadenopathy, malaise, a headache, or a fever may develop.
Conjunctivitis
All forms of conjunctivitis cause eye itching, burning, and pain along with photophobia, conjunctival injection, a foreign-body sensation, excessive tearing, and a feeling of fullness around the eye. Allergic conjunctivitis may also cause milky redness and a stringy eye discharge. Bacterial conjunctivitis typically causes brilliant redness and a mucopurulent discharge that may make the eyelids stick together. Fungal conjunctivitis produces a thick, purulent discharge and crusting and sticking of the eyelid. Viral conjunctivitis may cause copious tearing — but little discharge — and preauricular lymph node enlargement.
Dermatitis
Several types of dermatitis can cause pruritus accompanied by a skin lesion. Atopic dermatitis begins with intense, severe pruritus and an erythematous rash on dry skin at flexion points (antecubital fossa, popliteal area, and neck). During a flare-up, scratching may produce edema, scaling, and pustules. With chronic atopic dermatitis, lesions may progress to dry, scaly skin with white dermatographia, blanching, and lichenification.
Mild irritants and allergies can cause contact dermatitis, with itchy small vesicles that may ooze and scale and are surrounded by redness. A severe reaction can produce marked localized edema.
Dermatitis herpetiformis, most common in men between ages 20 and 50, initially causes intense pruritus and stinging. Between 8 and 12 hours later, symmetrically distributed lesions form on the buttocks, shoulders, elbows, and knees. Sometimes, they also form on the neck, face, and scalp. These lesions are erythematous and papular, bullous, or pustular.
Hepatobiliary disease
An important diagnostic clue to liver and gallbladder disease, pruritus is commonly accompanied by jaundice and may be generalized or localized to the palms and soles. Other characteristics include right upper quadrant pain, clay-colored stools, chills and a fever, flatus, belching and a bloated feeling, epigastric burning, and bitter fluid regurgitation. Later, liver disease may produce mental changes, ascites, bleeding tendencies, spider angiomas, palmar erythema, dry skin, fetor hepaticus, enlarged superficial abdominal veins, bilateral gynecomastia, testicular atrophy or menstrual irregularities, and hepatomegaly.
Herpes zoster
Within 2 to 4 days of a fever and malaise, pruritus, paresthesia or hyperesthesia, and severe, deep pain from cutaneous nerve involvement develop on the trunk or the arms and legs in a dermatome distribution. Up to 2 weeks after initial symptoms, red, nodular skin eruptions appear on the painful areas and become vesicular. About 10 days later, the vesicles rupture and form scabs.
Leukemia (chronic lymphocytic)
Pruritus is an uncommon finding in leukemia. More characteristic signs and symptoms include fatigue, malaise, generalized lymphadenopathy, a fever, hepatomegaly, splenomegaly, weight loss, pallor, bleeding, and palpitations.
Lichen simplex chronicus
Persistent rubbing and scratching cause localized pruritus and a circumscribed scaling patch with sharp margins. Later, the skin thickens and papules form.
Myringitis (chronic)
Myringitis produces pruritus in the affected ear, along with a purulent discharge and gradual hearing loss.
Pediculosis
A prominent symptom, pruritus occurs in the area of infestation. Pediculosis capitis (head lice) may also cause scalp excoriation from scratching, along with matted, foul-smelling, lusterless hair; occipital and cervical lymphadenopathy; and oval, gray-white nits on hair shafts.
Pediculosis corporis (body lice) initially causes small red papules (usually on the shoulders, trunk, or buttocks), which become urticarial from scratching. Later, rashes or wheals may develop. Untreated, pediculosis corporis produces dry, discolored, thickly encrusted, scaly skin with bacterial infection and scarring. In severe cases, it produces a headache, a fever, and malaise.
With pediculosis pubis (pubic lice), scratching commonly produces skin irritation. Nits or adult lice and erythematous, itching papules may appear in pubic hair or in hair around the anus, abdomen, or thighs.
Pityriasis rosea
Pityriasis rosea occasionally produces mild pruritus that’s aggravated by a hot bath or shower. It usually begins with an erythematous herald patch — a slightly raised, oval lesion about 2 to 6 cm in diameter. After a few days or weeks, scaly yellow-tan or erythematous patches erupt on the trunk and extremities and persist for 2 to 6 weeks. Occasionally, these patches are macular, vesicular, or urticarial.
Psoriasis
Pruritus and pain are common in psoriasis. This skin disorder typically begins with small erythematous papules that enlarge or coalesce to form red elevated plaques with silver scales on the scalp, chest, elbows, knees, back, buttocks, and genitals. Nail pitting may occur.
Scabies
Typically, scabies causes localized pruritus that awakens the patient. It may become generalized and persist for up to 2 weeks after treatment. Threadlike lesions several millimeters long appear with a swollen nodule or red papule.
Gender Cue: In males, crusty lesions may form on the glans penis, penile shaft, and scrotum. In females, lesions may also be found on or around the nipples. In both sexes, the lesions have a predilection for skin folds. Crusty excoriated lesions form on the wrists, elbows, axillae, waistline, behind the knees, and ankles. Excoriation from scratching is common.
Tinea pedis
Tinea pedis is a fungal infection that causes severe foot pruritus, pain with walking, scales and blisters between the toes, and a dry, scaly squamous inflammation on the entire sole.
Urticaria
Extreme pruritus and stinging occur as transient, erythematous or whitish wheals form on the skin or mucous membranes. Prickly sensations typically precede the wheals, which may affect any part of the body and may range from pinpoint to palm-sized or larger.
Vaginitis
Vaginitis commonly causes localized pruritus and a foul-smelling vaginal discharge that may be purulent, white or gray, and curdlike. Perineal pain and urinary dysfunction may also occur.
Other causes
Herb Alert
Ingestion of fruit pulp from the ginkgo tree can cause rapid formation of vesicles, resulting in severe itching.
Bedbug bites
Typically, bedbug bites produce itching and burning over the ankles and lower legs, along with clusters of purpuric spots.
Drug hypersensitivity
When mild and localized, an allergic reaction to such drugs as penicillin and sulfonamides can cause pruritus, erythema, an urticarial rash, and edema. However, with a severe drug reaction, anaphylaxis may occur.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Signs & Symptoms (Third Edition), 2006
Heat intolerance:
Medical causes
(Handbook of Signs & Symptoms (Third Edition))
Hypothalamic disease
With hypothalamic disease, body temperature fluctuates dramatically, causing alternating heat and cold intolerance
Related features include amenorrhea, disturbed sleep patterns, increased thirst and urination, increased appetite with weight gain, impaired visual acuity, a headache, and personality changes, such as bursts of rage or laughter Common causes of hypothalamic disease are pituitary adenoma and hypothalamic and pineal tumors.
Thyrotoxicosis
A classic symptom of thyrotoxicosis, heat intolerance may be accompanied by an enlarged thyroid, nervousness, weight loss despite increased appetite, diaphoresis, diarrhea, tremor, and palpitations Although exophthalmos is characteristic, many patients don’t display this sign
Associated findings may affect virtually every body system. Some common findings include irritability, difficulty concentrating, mood swings, insomnia, muscle weakness, fatigue, lid lag, tachycardia, full and bounding pulse, a widened pulse pressure, dyspnea, amenorrhea, and gynecomastia. Typically, the patient’s skin is warm and flushed; premature graying and alopecia occur in both sexes.
Other causes
Drugs
Amphetamines, amphetamine-like appetite suppressants, and excessive doses of thyroid hormone may cause heat intolerance Anticholinergics may interfere with sweating, resulting in heat intolerance.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Signs & Symptoms (Third Edition), 2006
Pruritus ani:
Causes
(Professional Guide to Diseases (Eighth Edition))
Factors that contribute to pruritus ani include overcleaning of the perianal area (harsh soap, vigorous rubbing with a washcloth or toilet paper); minor trauma caused by straining to defecate; poor hygiene; sensitivity to spicy foods, coffee, alcohol, food preservatives, perfumed or colored toilet paper, detergents, or certain fabrics; specific medications (antibiotics, antihypertensives, or antacids that cause diarrhea); excessive sweating (in occupations associated with physical labor or high stress levels); anal skin tags; systemic disease, especially diabetes; certain skin lesions, such as those associated with squamous cell carcinoma, basal cell carcinoma, Bowen’s disease, Paget’s disease, melanoma, syphilis, and tuberculosis; fungal or parasitic infection; and local anorectal disease (fissure, hemorrhoids, and fistula).
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Heat syndrome:
Causes
(Professional Guide to Diseases (Eighth Edition))
Normally, people adjust to excessive temperatures via complex cardiovascular and neurologic changes that are coordinated by the hypothalamus. Heat loss offsets heat production to regulate the body temperature. It does this by evaporation (sweating) or vasodilation, which cools the body’s surface by radiation, conduction, and convection.
However, heat production increases with exercise, infection, and the use of certain drugs such as amphetamines, and heat loss decreases with high temperatures or humidity, lack of acclimatization, excess clothing, obesity, dehydration, cardiovascular disease, sweat gland dysfunction, and the use of such drugs as phenothiazines and anticholinergics. When heat loss mechanisms fail to offset heat production, the body retains heat and may develop heat syndrome.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Pruritus:
Medical causes
(Professional Guide to Signs & Symptoms (Fifth Edition))
Anemia (iron deficiency)
This disorder occasionally produces pruritus. Initially asymptomatic, anemia can later cause exertional dyspnea, fatigue, listlessness, pallor, irritability, headache, tachycardia, poor muscle tone and, possibly, murmurs. Chronic anemia causes spoon-shaped (koilonychia) and brittle nails (cheilosis), cracked mouth corners, a smooth tongue (glossitis), and dysphagia.
Anthrax (cutaneous)
Anthrax is an acute infectious disease caused by the gram-positive, spore-forming bacterium Bacillus anthracis. It can occur in humans who are exposed to infected animals, tissue from infected animals, or biological warfare. Cutaneous anthrax occurs when the bacterium enters a cut or abrasion on the skin. The infection begins as a small, painless or pruritic macular or papular lesion resembling an insect bite. Within 1 to 2 days it develops into a vesicle and then a painless ulcer with a characteristic black, necrotic center. Lymphadenopathy, malaise, headache, or fever may develop.
Conjunctivitis
All forms of conjunctivitis cause eye itching, burning, and pain along with photophobia, conjunctival injection, a foreign-body sensation, excessive tearing, and a feeling of fullness around the eye. Allergic conjunctivitis may also cause milky redness and a stringy eye discharge. Bacterial conjunctivitis typically causes brilliant redness and a mucopurulent, discharge that may make the eyelids stick together. Fungal conjunctivitis produces a thick, purulent discharge and crusting and sticking of the eyelid. Viral conjunctivitis may cause copious tearing—but little discharge—and preauricular lymph node enlargement.
Dermatitis
Several types of dermatitis can cause pruritus accompanied by a skin lesion. Atopic dermatitis begins with intense, severe pruritus and an erythematous rash on dry skin at flexion points (antecubital fossa, popliteal area, and neck). During a flare-up, scratching may produce edema, scaling, and pustules. With chronic atopic dermatitis, lesions may progress to dry, scaly skin with white dermatographia, blanching, and lichenification.
Mild irritants and allergies can cause contact dermatitis, with itchy small vesicles that may ooze and scale and are surrounded by redness. A severe reaction can produce marked localized edema.
Dermatitis herpetiformis, most common in men between ages 20 and 50, initially causes intense pruritus and stinging. Between 8 and 12 hours later, symmetrically distributed lesions form on the buttocks, shoulders, elbows, and knees. Sometimes, they also form on the neck, face, and scalp. These lesions are erythematous and papular, bullous, or pustular.
Enterobiasis
Also known as pinworm or seatworm, this benign intestinal disease results from infection by Enterobius vermicularis. Adult worms live in the intestine; females migrate to the perianal region to deposit their eggs, causing intense perianal pruritus.
Hemorrhoids
Anal pruritus may occur in patients with hemorrhoids along with rectal pain and constipation. External hemorrhoids may be seen outside the external anal sphincter; internal hemorrhoids are less obvious and less painful but more likely to cause rectal bleeding.
Hepatobiliary disease
An important diagnostic clue to liver and gallbladder disease, pruritus is commonly accompanied by jaundice and may be generalized or localized to the palms and soles. Other characteristics include right-upper-quadrant pain, clay-colored stools, chills and fever, flatus, belching and a bloated feeling, epigastric burning, and bitter fluid regurgitation. Later, liver disease may produce mental changes, ascites, bleeding tendencies, spider angiomas, palmar erythema, dry skin, fetor hepaticus, enlarged superficial abdominal veins, bilateral gynecomastia, testicular atrophy or menstrual irregularities, and hepatomegaly.
Herpes zoster
Within 2 to 4 days of fever and malaise, pruritus, paresthesia or hyperesthesia, and severe, deep pain from cutaneous nerve involvement develop on the trunk or the arms and legs in a dermatome distribution. Up to 2 weeks after initial symptoms, red, nodular skin eruptions appear on the painful areas and become vesicular. About 10 days later, the vesicles rupture and form scabs.
Hodgkin’s disease
This disease, which is most common in young adults, occasionally causes severe and unexplained itching. As the disease progresses, pruritus may become severe and unresponsive to treatment. Early nonspecific findings include persistent fever (occasionally, cyclic fever and chills), night sweats, fatigue, weight loss, malaise, and painless swelling of a cervical lymph node. Other lymph nodes may enlarge rapidly and cause pain, or they may enlarge slowly and be painless. Later findings include retroperitoneal node enlargement, hepatomegaly, splenomegaly, dyspnea, dysphagia, dry cough, hyperpigmentation, jaundice, and pallor.
Leukemia (chronic lymphocytic)
Pruritus is an uncommon finding in this disorder. More characteristic signs and symptoms include fatigue, malaise, generalized lymphadenopathy, fever, hepatomegaly, splenomegaly, weight loss, pallor, bleeding, and palpitations.
Lichen planus
This uncommon skin disease can cause moderate to severe pruritus that’s aggravated by stress. Characteristic oral lesions (white or gray, velvety, lacy, threadlike papules) develop on the buccal mucosa and may cause pain. Violet papules with white lines or spots develop later, usually on the genitalia, lower back, ankles, and shins. Nail distortion and atrophic alopecia may also occur.
Lichen simplex chronicus
Persistent rubbing and scratching cause localized pruritus and a circumscribed scaling patch with sharp margins. Later, the skin thickens and papules form.
Mastocytosis
With this disorder, reddish brown macules or papules (urticaria pigmentosa), along with patchy erythema and telangiectasia occur. Other signs and symptoms include pruritus, flushing, tachycardia, hypotension, and nausea.
Multiple myeloma
Infrequently, this disorder produces pruritus. Other findings include severe, constant back pain that increases with exercise; achiness; joint swelling and tenderness; fever; malaise; slight peripheral neuropathy; and purpura.
Mycosis fungoides
Pruritus may precede other symptoms of this neoplastic disease by 10 years. It may persist into the first, or premycotic, stage, accompanied by erythematous lesions.
Myringitis (chronic)
This disorder produces pruritus in the affected ear, along with a purulent discharge and gradual hearing loss.
Pediculosis
A prominent symptom, pruritus occurs in the area of infestation. Pediculosis capitis (head lice) may also cause scalp excoriation from scratching, along with matted, foul-smelling, lusterless hair; occipital and cervical lymphadenopathy; and oval, gray-white nits on hair shafts.
Pediculosis corporis (body lice) initially causes small red papules (usually on the shoulders, trunk, or buttocks), which become urticarial from scratching. Later, rashes or wheals may develop. Untreated, pediculosis corporis produces dry, discolored, thickly encrusted, scaly skin with bacterial infection and scarring. In severe cases, it produces headache, fever, and malaise.
With pediculosis pubis (pubic lice), scratching commonly produces skin irritation. Nits or adult lice and erythematous, itching papules may appear in pubic hair or hair around the anus, abdomen, or thighs.
Pityriasis rosea
This disorder occasionally produces mild pruritus that’s aggravated by a hot bath or shower. It usually begins with an erythematous herald patch—a slightly raised, oval lesion about 2 to 6 cm in diameter. After a few days or weeks, scaly yellow-tan or erythematous patches erupt on the trunk and extremities and persist for 2 to 6 weeks. Occasionally, these patches are macular, vesicular, or urticarial.
Polycythemia vera
This hematologic disorder can produce pruritus that’s generalized or localized to the head, neck, face, and extremities. The itching is typically aggravated by a hot bath or shower and can last from a few minutes to an hour. The patient’s oral mucosa may be deep purplish red, especially on the gingivae and tongue. His engorged gingivae ooze blood with even slight trauma.
Related findings include headache, dizziness, fatigue, dyspnea, paresthesia, impaired mentation, tinnitus, double or blurred vision, scotoma, hypotension, intermittent claudication, urticaria, ruddy cyanosis, and ecchymosis. GI effects include gastric distress, weight loss, and hepatosplenomegaly.
Psoriasis
Pruritus and pain are common in psoriasis. This skin disorder typically begins with small erythematous papules that enlarge or coalesce to form red elevated plaques with silver scales on the scalp, chest, elbows, knees, back, buttocks, and genitals. Nail pitting may occur.
Psychogenic pruritus
Localized or generalized pruritus occurs without symptoms of dermatologic or systemic disease. Anxiety or emotional lability may be evident.
Renal failure (chronic)
Pruritus may develop gradually or suddenly with this disorder. It may be accompanied by ammonia breath odor, oliguria or anuria, lassitude, fatigue, irritability, decreased mental acuity, convulsions, coarse muscular twitching, muscle cramps, peripheral neuropathies, and coma. Renal failure also causes diverse GI signs and symptoms, such as anorexia, constipation or diarrhea, nausea, and vomiting.
Scabies
Typically, scabies causes localized pruritus that awakens the patient. It may become generalized and persist up to 2 weeks after treatment. Threadlike lesions several millimeters long appear with a swollen nodule or red papule.
Gender Cue: In males, crusty lesions may form on the glans penis, penile shaft, and scrotum. In females, lesions may also be found on or around nipples. In both sexes the lesions have a predilection for skin folds. Crusty excoriated lesions form on the wrists, elbows, axillae, waistline, behind the knees and ankles. Excoriation from scratching is common.
Thyrotoxicosis
Generalized pruritus may precede or accompany the characteristic signs and symptoms of this disorder: tachycardia, palpitations, weight loss despite increased appetite, diarrhea, tremors, an enlarged thyroid, dyspnea, nervousness, diaphoresis, heat intolerance and, possibly, exophthalmos.
Tinea pedis
This fungal infection causes severe foot pruritus, pain with walking, scales and blisters between the toes, and a dry, scaly squamous inflammation on the entire sole.
Urticaria
Extreme pruritus and stinging occur as transient erythematous or whitish wheals form on the skin or mucous membranes. Prickly sensations typically precede the wheals, which may affect any part of the body and may range from pinpoint to palm-sized or larger.
Vaginitis
This disorder commonly causes localized pruritus and foul-smelling vaginal discharge that may be purulent, white or gray, and curdlike. Perineal pain and urinary dysfunction may also occur.
Other causes
Bedbug bites
Typically, bedbug bites produce itching and burning over the ankles and lower legs, along with clusters of purpuric spots.
Drug hypersensitivity
When mild and localized, an allergic reaction to such drugs as penicillin and sulfonamides can cause pruritus, erythema, an urticarial rash, and edema. However, with a severe drug reaction, anaphylaxis may occur.
Herb alert Ingestion of fruit pulp from the ginkgo tree can cause rapid formation of vesicles, resulting in severe itching.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Signs & Symptoms (Fifth Edition), 2006
Heat intolerance:
Medical causes
(Professional Guide to Signs & Symptoms (Fifth Edition))
Hypothalamic disease
In this rare disease, body temperature fluctuates dramatically, causing alternating heat and cold intolerance. Related features include amenorrhea, disturbed sleep patterns, increased thirst and urination, increased appetite with weight gain, impaired visual acuity, headache, and personality changes, such as bursts of rage or laughter. Common causes of hypothalamic disease are pituitary adenoma and hypothalamic and pineal tumors.
Thyrotoxicosis
A classic symptom of thyrotoxicosis, heat intolerance may be accompanied by an enlarged thyroid gland, nervousness, weight loss despite increased appetite, diaphoresis, diarrhea, tremor, and palpitations. Although exophthalmos is characteristic, many patients don’t display this sign. Associated findings may affect virtually every body system. Some common findings include irritability, difficulty concentrating, mood swings, insomnia, muscle weakness, fatigue, lid lag, tachycardia, full and bounding pulse, widened pulse pressure, dyspnea, amenorrhea, and gynecomastia. Typically, the patient’s skin is warm and flushed; premature graying and alopecia occur in both sexes.
Other causes
Drugs
Amphetamines, amphetamine-like appetite suppressants, and excessive doses of thyroid hormone may cause heat intolerance. Anticholinergics may interfere with sweating, resulting in heat intolerance.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Signs & Symptoms (Fifth Edition), 2006
Heat syndrome:
Causes
(Handbook of Diseases)
Normally, humans adjust to excessive temperatures by complex cardiovascular and neurologic changes that are coordinated by the hypothalamus. Heat loss offsets heat production to regulate the body temperature. This is done by evaporation (sweating) or vasodilation, which cools the body’s surface by radiation, conduction, and convection.
Heat production increases with exercise, infection, and use of drugs such as amphetamines.
Heat loss decreases with high temperatures or humidity, lack of acclimatization, excess clothing, obesity, dehydration, cardiovascular disease, sweat gland dysfunction, and use of drugs, such as phenothiazines and anticholinergics.
When heat loss mechanisms fail to offset heat production, the body retains heat and heat syndrome may develop.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Pruritus:
Medical causes
(Signs & Symptoms: A 2-in-1 Reference for Nurses)
Anemia (iron deficiency)
Anemia occasionally produces pruritus. Initially asymptomatic, anemia can later cause exertional dyspnea, fatigue, listlessness, pallor, irritability, headache, tachycardia, poor muscle tone and, possibly, murmurs. Chronic anemia causes spoon-shaped (koilonychia) and brittle nails (cheilosis), cracked mouth corners, a smooth tongue (glossitis), and dysphagia.
Anthrax (cutaneous)
A cutaneous anthrax infection begins as a small, painless or pruritic, macular or papular lesion resembling an insect bite. Within 1 to 2 days, it develops into a vesicle and then a painless ulcer with a characteristic black, necrotic center. Lymphadenopathy, malaise, headache, or fever may develop.
Conjunctivitis
All forms of conjunctivitis cause eye itching, burning, and pain along with photophobia, conjunctival injection, a foreign-body sensation, excessive tearing, and a feeling of fullness around the eye. Allergic conjunctivitis may also cause milky redness and a stringy eye discharge. Bacterial conjunctivitis typically causes brilliant redness and a mucopurulent discharge that may make the eyelids stick together. Fungal conjunctivitis produces a thick, purulent discharge and crusting and sticking of the eyelid. Viral conjunctivitis may cause copious tearing — but little discharge — and preauricular lymph node enlargement.
Dermatitis
Several types of dermatitis can cause pruritus accompanied by a skin lesion. Atopic dermatitis begins with intense, severe pruritus and an erythematous rash on dry skin at flexion points (antecubital fossa, popliteal area, and neck). During a flare-up, scratching may produce edema, scaling, and pustules. With chronic atopic dermatitis, lesions may progress to dry, scaly skin with white dermatographism, blanching, and lichenification.
Mild irritants and allergies can cause contact dermatitis, with itchy, small vesicles that may ooze and scale and are surrounded by redness. A severe reaction can produce marked localized edema.
Dermatitis herpetiformis, most common in men between ages 20 and 50, initially causes intense pruritus and stinging. Between 8 and 12 hours later, symmetrically distributed lesions form on the buttocks, shoulders, elbows, and knees. Sometimes, they also form on the neck, face, and scalp. These lesions are erythematous and papular, bullous, or pustular.
Enterobiasis
Also known as pinworm or seatworm, this helminthic infection produces intense perianal pruritus, especially at night, when the female worm leaves the anus to deposit ova. Pruritus causes irritability, scratching, skin irritation and, sometimes, vaginitis.
Hemorrhoids
Anal pruritus may occur in patients with hemorrhoids along with rectal pain and constipation. External hemorrhoids may be seen outside the external anal sphincter; internal hemorrhoids are less obvious and less painful but more likely to cause rectal bleeding.
Hepatobiliary disease
An important diagnostic clue to liver and gallbladder disease, pruritus is commonly accompanied by jaundice and may be generalized or localized to the palms and soles. Other characteristics include right-upper-quadrant pain, clay-colored stools, chills and fever, flatus, belching and a bloated feeling, epigastric burning, and bitter fluid regurgitation. Later, liver disease may produce mental changes, ascites, bleeding tendencies, spider angiomas, palmar erythema, dry skin, fetor hepaticus, enlarged superficial abdominal veins, bilateral gynecomastia, testicular atrophy or menstrual irregularities, and hepatomegaly.
Herpes zoster
In herpes zoster, within 4 days of fever and malaise, pruritus, paresthesia or hyperesthesia, and severe, deep pain from cutaneous nerve involvement develop on the trunk or the arms and legs in a dermatome distribution. Up to 2 weeks after initial symptoms, red, nodular skin eruptions appear on the painful areas and become vesicular. About 10 days later, the vesicles rupture and form scabs.
Hodgkin’s disease
Hodgkin’s disease occasionally causes severe and unexplained itching. As the disease progresses, pruritus may become severe and unresponsive to treatment. Early nonspecific findings include persistent fever (occasionally, cyclic fever and chills), night sweats, fatigue, weight loss, malaise, and painless swelling of a cervical lymph node. Other lymph nodes may enlarge rapidly and cause pain, or they may enlarge slowly and be painless. Later findings include retroperitoneal node enlargement, hepatomegaly, splenomegaly, dyspnea, dysphagia, dry cough, hyperpigmentation, jaundice, and pallor.
Lichen simplex chronicus
Lichen simplex chronicus is due to persistent rubbing and scratching of the skin, causing localized pruritus and a circumscribed scaling patch with sharp margins. Later, the skin thickens and papules form. This condition usually affects areas easily reached, such as ankles, lower legs, anogenital area, back of neck, and ears.
Pediculosis
A prominent symptom of pediculosis, pruritus occurs in the area of infestation. Pediculosis capitis (head lice) may also cause scalp excoriation from scratching, along with matted, foul-smelling, lusterless hair; occipital and cervical lymphadenopathy; and oval, gray-white nits on hair shafts.
Pediculosis corporis (body lice) initially causes small red papules (usually on the shoulders, trunk, or buttocks), which become urticarial from scratching. Later, rashes or wheals may develop. Left untreated, pediculosis corporis produces dry, discolored, thickly encrusted, scaly skin with bacterial infection and scarring. In severe cases, it produces headache, fever, and malaise.
With pediculosis pubis (pubic lice), scratching commonly produces skin irritation. Nits or adult lice and erythematous, itching papules may appear in pubic hair or hair around the anus, abdomen, or thighs.
Pityriasis rosea
Pityriasis rosea occasionally produces mild pruritus that’s aggravated by a hot bath or shower. It usually begins with an erythematous herald patch — a slightly raised, oval lesion about 2 to 6 cm in diameter. After a few days or weeks, scaly yellow-tanor erythematous patches erupt on the trunk and extremities and persist for 2 to 6 weeks. Occasionally, these patches are macular, vesicular, or urticarial.
Polycythemia vera
Polycythemia vera, a hematologic disorder, can produce pruritus that’s generalized or localized to the head, neck, face, and extremities. The itching is typically aggravated by a hot bath or shower and can last from a few minutes to an hour. The patient’s oral mucosa may be deep purplish red, especially on the gingivae and tongue. His engorged gingivae ooze blood with even slight trauma.
Related findings include headache, dizziness, fatigue, dyspnea, paresthesia, impaired mentation, tinnitus, double or blurred vision, scotoma, hypotension, intermittent claudication, urticaria, ruddy cyanosis, and ecchymosis. GI effects include gastric distress, weight loss, and hepatosplenomegaly.
Psoriasis
Pruritus and pain are common in psoriasis. This skin disorder typically begins with small erythematous papules that enlarge or coalesce to form red, elevated plaques with silver scales on the scalp, chest, elbows, knees, back, buttocks, and genitals. Nail pitting may occur.
Renal failure (chronic)
Pruritus may develop gradually or suddenly with chronic renal failure. It may be accompanied by ammonia breath odor, oliguria or anuria, lassitude, fatigue, irritability, decreased mental acuity, convulsions, coarse muscular twitching, muscle cramps, peripheral neuropathies,and coma. Renal failure also causes diverse GI signs and symptoms, such as anorexia, constipation or diarrhea, nausea, and vomiting.
Scabies
Typically, scabies causes localized pruritus that awakens the patient. It may become generalized and persist up to 2 weeks after treatment. Threadlike lesions several millimeters long appear with a swollen nodule or red papule.
Thyrotoxicosis
Generalized pruritus may precede or accompany the characteristic signs and symptoms of thyrotoxicosis: tachycardia, palpitations, weight loss despite increased appetite, diarrhea, tremors, an enlarged thyroid, dyspnea, nervousness, diaphoresis, heat intolerance and, possibly, exophthalmos.
Tinea pedis
Tinea pedis, also called athlete’s foot, is a fungal infection that causes severe foot pruritus, pain with walking, scales and blisters between the toes, and a dry, scaly squamous inflammation on the entire sole. The affected skin may appear red and inflamed.
Urticaria
With urticaria, extreme pruritus and stinging occur as transient erythematous or whitish wheals form on the skin or mucous membranes. Prickly sensations typically precede the wheals, which may affect any part of the body and may range from pinpoint to palm-sized or larger.
Vaginitis
Vaginitis commonly causes localized pruritus and foul-smelling vaginal discharge that may be purulent, white or gray, and curdlike. Perineal pain and urinary symptoms, such as burning and frequency, may also occur.
Other causes
Bedbug bites
Typically, bedbug bites produce itching and burning over the ankles and lower legs, along with clusters of purpuric spots.
Drug hypersensitivity
When mild and localized, an allergic reaction to such drugs as penicillin and sulfonamides can cause pruritus, erythema, an urticarial rash, and edema. However, with a severe drug reaction, anaphylaxis may occur.
» READ BOOK EXCERPT ONLINE »
Source: Signs & Symptoms: A 2-in-1 Reference for Nurses, 2007
Pruritus:
Medical causes
(Nursing: Interpreting Signs and Symptoms)
Anemia (iron deficiency).Iron deficiency anemia occasionally produces pruritus. Initially producing no symptoms, anemia can later cause exertional dyspnea, fatigue, listlessness, pallor, irritability, headache, tachycardia, poor muscle tone and, possibly, murmurs. Chronic anemia causes spoon-shaped (koilonychia) and brittle nails, cracked mouth corners (cheilosis), a smooth tongue (glossitis), and dysphagia.
Anthrax (cutaneous).Anthrax infection begins as a small, painless or pruritic macular or papular lesion resembling an insect bite. Within 1 or 2 days, it develops into a vesicle and then a painless ulcer with a characteristic black, necrotic center. Lymphadenopathy, malaise, headache, or fever may develop.
Conjunctivitis.All forms of conjunctivitis cause eye itching, burning, and pain along with photophobia, conjunctival injection, a foreign-body sensation, excessive tearing, and a feeling of fullness around the eye. Allergic conjunctivitis may also cause milky redness and a stringy eye discharge. Bacterial conjunctivitis typically causes brilliant redness and a mucopurulent discharge that may make the eyelids stick together. Fungal conjunctivitis produces a thick, purulent discharge and crusting and sticking of the eyelid. Viral conjunctivitis may cause copious tearing—but little discharge—and preauricular lymph node enlargement.
Dermatitis.Several types of dermatitis can cause pruritus accompanied by a skin lesion. Atopic dermatitis begins with intense, severe pruritus and an erythematous rash on dry skin at flexion points (antecubital fossa, popliteal area, and neck). During a flare-up, scratching may produce edema, scaling, and pustules. With chronic atopic dermatitis, lesions may progress to dry, scaly skin with white dermatographia, blanching, and lichenification.
Mild irritants and allergies can cause contact dermatitis, with itchy small vesicles that may ooze and scale and are surrounded by redness. A severe reaction can produce marked localized edema.
Dermatitis herpetiformis, initially causes intense pruritus and stinging. Between 8 and 12 hours later, symmetrically distributed lesions form on the buttocks, shoulders, elbows, and knees. Sometimes, they also form on the neck, face, and scalp. These lesions are erythematous and papular, bullous, or pustular.
Hepatobiliary disease.An important diagnostic clue to liver and gallbladder disease, pruritus is commonly accompanied by jaundice and may be generalized or localized to the palms and soles. Other characteristics include right upper quadrant pain, clay-colored stools, chills and fever, flatus, belching and a bloated feeling, epigastric burning, and bitter fluid regurgitation. Later, liver disease may produce mental changes, ascites, bleeding tendencies, spider angiomas, palmar erythema, dry skin, fetor hepaticus, enlarged superficial abdominal veins, bilateral gynecomastia, testicular atrophy or menstrual irregularities, and hepatomegaly.
Herpes zoster.With herpes zoster, within 2 to 4 days of a fever and malaise, pruritus, paresthesia or hyperesthesia, and severe, deep pain from cutaneous nerve involvement develop on the trunk or the arms and legs in a dermatome distribution. Up to 2 weeks after initial symptoms, red, nodular skin eruptions appear on the painful areas and become vesicular. About 10 days later, the vesicles rupture and form scabs.
Leukemia (chronic lymphocytic).Pruritus is an uncommon finding in leukemia. More characteristic signs and symptoms include fatigue, malaise, generalized lymphadenopathy, fever, hepatomegaly, splenomegaly, weight loss, pallor, bleeding, and palpitations.
Lichen simplex chronicus.Persistent rubbing and scratching cause localized pruritus and a circumscribed scaling patch with sharp margins. Later, the skin thickens and papules form.
Myringitis (chronic).Myringitis produces pruritus in the affected ear, along with a purulent discharge and gradual hearing loss.
Pediculosis.A prominent symptom of pediculosis, pruritus occurs in the area of infestation. Pediculosis capitis (head lice) may also cause scalp excoriation from scratching, along with matted, foul-smelling, lusterless hair; occipital and cervical lymphadenopathy; and oval, gray-white nits on hair shafts.
Pediculosis corporis (body lice) initially causes small red papules (usually on the shoulders, trunk, or buttocks), which become urticarial from scratching. Later, rashes or wheals may develop. Untreated, pediculosis corporis produces dry, discolored, thickly encrusted, scaly skin with bacterial infection and scarring. In severe cases, it produces headache, fever, and malaise.
With pediculosis pubis(pubic lice), scratching commonly produces skin irritation. Nits or adult lice and erythematous, itching papules may appear in pubic hair or in hair around the anus, abdomen, or thighs.
Pityriasis rosea.Pityriasis rosea occasionally produces mild pruritus that's aggravated by a hot bath or shower. It usually begins with an erythematous herald patch—a slightly raised, oval lesion about 2 to 6 cm in diameter. After a few days or weeks, scaly yellow-tan or erythematous patches erupt on the trunk and extremities and persist for 2 to 6 weeks. Occasionally, these patches are macular, vesicular, or urticarial.
Psoriasis.Pruritus and pain are common in psoriasis. This skin disorder typically begins with small erythematous papules that enlarge or coalesce to form red elevated plaques with silver scales on the scalp, chest, elbows, knees, back, buttocks, and genitals. Nail pitting may occur.
Scabies.Typically, scabies causes localized pruritus that awakens the patient. It may become generalized and persist for up to 2 weeks after treatment. Threadlike lesions several millimeters long appear with a swollen nodule or red papule.
Tinea pedis.Tinea pedis is a fungal infection that causes severe foot pruritus, pain with walking, scales and blisters between the toes, and a dry, scaly squamous inflammation on the entire sole.
Urticaria.With urticaria, extreme pruritus and stinging occur as transient, erythematous or whitish wheals form on the skin or mucous membranes. Prickly sensations typically precede the wheals, which may affect any part of the body and may range from pinpoint to palm-size or larger.
Vaginitis.Vaginitis commonly causes localized pruritus and a foul-smelling vaginal discharge that may be purulent, white or gray, and curdlike. Perineal pain and urinary dysfunction may also occur.
Other causes
Bedbug bites.Typically, bedbug bites produce itching and burning over the ankles and lower legs, along with clusters of purpuric spots.
Drug hypersensitivity.When mild and localized, an allergic reaction to such drugs as penicillin and sulfonamides can cause pruritus, erythema, an urticarial rash, and edema. However, with a severe drug reaction, anaphylaxis may occur.
» READ BOOK EXCERPT ONLINE »
Source: Nursing: Interpreting Signs and Symptoms, 2007
Heat intolerance:
Medical causes
(Nursing: Interpreting Signs and Symptoms)
Hypothalamic disease.With hypothalamic disease, body temperature fluctuates dramatically, causing alternating heat and cold intolerance. Related features include amenorrhea, disturbed sleep patterns, increased thirst and urination, increased appetite with weight gain, impaired visual acuity, a headache, and personality changes, such as bursts of rage or laughter. Common causes of hypothalamic disease are pituitary adenoma and hypothalamic and pineal tumors.
Thyrotoxicosis.A classic symptom of thyrotoxicosis, heat intolerance may be accompanied by an enlarged thyroid, nervousness, weight loss despite increased appetite, diaphoresis, diarrhea, tremor, and palpitations. Although exophthalmos is characteristic, many patients don't display this sign. Associated findings may affect virtually every body system. Some common findings include irritability, difficulty concentrating, mood swings, insomnia, muscle weakness, fatigue, lid lag, tachycardia, full and bounding pulse, a widened pulse pressure, dyspnea, amenorrhea, and gynecomastia. Typically, the patient's skin is warm and flushed; premature graying and alopecia occur in both sexes.
Other causes
Drugs.Amphetamines, amphetamine-like appetite suppressants, and excessive doses of thyroid hormone may cause heat intolerance. Anticholinergics may interfere with sweating, resulting in heat intolerance.
» READ BOOK EXCERPT ONLINE »
Source: Nursing: Interpreting Signs and Symptoms, 2007
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