Diagnosis of Hypocalcemia

• Hypoparathyroidism
  –Often occurs after thyroidectomy or parathyoidectomy
  –Infiltrative diseases of the parathyroid gland (e.g., hemochromatosis, Wilson's disease, sarcoidosis, tuberculosis)
  –Pseudohypoparathyroidism (parathyroid hormone resistance)
  –Idiopathic (autoimmune)

• Medications (e.g., diuretics, heparin, foscarnet, cimetidine, glucagon, phosphates, aminoglycosides, theophylline, cisplatin)
• Vitamin D deficiency
  –Poor oral intake and/or absent sun exposure
  –Malabsorption
  –Hepatic and/or renal failure
  –Anticonvulsant use
• Pancreatitis
• Alkalosis (especially respiratory alkalosis)
• Sepsis
• Shock
• Burns
• Magnesium deficiency (often seen in alcoholism)
• Hyperphosphatemia
• Alcoholism (may directly suppress PTH and/or deplete magnesium)
• Postoperative (usually transient)
• Post-blood transfusion
• Malignancy
  –Medullary carcinoma of the thyroid
  –Osteoblastic metastases
• Familial hypocalcemia
• DiGeorge's syndrome (congenital absence of the parathyroid glands)
• Polyglandular autoimmune syndrome, type I (hypoparathyroidism, adrenal insufficiency, and mucocutaneous candidiasis)
• Rickets

Workup and Diagnosis

• History and physical examination
  –Severity of symptoms depends on rapidity of fall in serum calcium
  –Symptoms include weakness, fatigue, muscle cramping and spasm (difficulty speaking may indicate laryngeal spasm), paresthesias (perioral or fingertip), abdominal pain, nausea/vomiting, irritability, and depression
  –Severe hypocalcemia may cause delirium, psychosis, and seizures
  –Skin exam may reveal patchy hair loss, dry and/or scaly skin, hyperpigmentation, brittle nails, and mucocutaneous candidiasis
  –Trousseau's sign: Carpal spasms upon inflation of a blood pressure cuff for 2 to 3 minutes
  –Chvostek's sign: Tapping of cranial nerve VII (anterior to ear) causes twitching of facial muscles
  –Cardiac arrhythmias, decreased myocardial contractility (may lead to CHF), hypotension

• Initial labs include serum calcium, ionized calcium, albumin, magnesium, phosphorus, BUN/creatinine, CBC, and amylase/lipase
• Correct calcium for hypoalbuminemia: Serum Ca^₂+ decreases by 0.8 for each 1 g/dL drop in albumin (although ionized calcium is normal)
• Measure parathyroid hormone and vitamin D levels
  –Decreased in primary hypoparathyroidism
  –Elevated in renal failure, malabsorption, vitamin D deficiency, and pseudohypoparathyroidism
• ECG may reveal prolonged QT interval

» READ BOOK EXCERPT ONLINE »

Source: In a Page: Signs and Symptoms, 2004

Hypocalcemia: Differential Diagnosis
(In A Page: Pediatric Signs and Symptoms)

• Hypoparathyroidism
  –Congenital: Transient neonatal vs heritable forms
  –Acquired: Autoimmune, postsurgical, radioablation, infiltrative
  –DiGeorge Syndrome
  –Polyglandular autoimmune disease type 1 (Blizzard syndrome)
  –Pseudohypoparathyroidism (PHP) or PTH resistance
        –PHP type IA (Albright dereditary osteodystrophy)
        –PHP type IB, type II

• Vitamin D deficiency
  –Nutritional deprivation
        –Most common cause of rickets
        –Seen in breast-fed and black children
  –Malabsorption/steatorrhea/liver disease
  –1-αhydroxylase deficiency
  –Chronic renal disease

• Calcium deficiency
  –Nutritional deprivation
  –Malabsorption
  –Hypercalciuria
• Hypomagnesemia
  –Impairs secretion of, and end-organ responsiveness to, PTH
  –Inherited forms
  –Intestinal losses
  –Renal wasting: RTA, drugs
• Hyperphosphatemia
• Hypoproteinemia
  –Total calcium is a measure of calcium bound to albumin
• Drugs
  –Loop diuretics (furosemide) promote renal calcium excretion
  –Anticonvulsants interfere with GI vitamin D absorption
  –Antacids impair GI calcium absorption
  –Antineoplastic agents
  –Citrated blood products
• Critical illness
  –Rhabdomyolysis
  –Toxic shock syndrome
  –Pancreatitis
• Organic acidemia
• Infant of a diabetic mother

Workup and Diagnosis

• History
  –Age at onset, age developmental milestones reached
  –Dietary intake, recurrent infections, medications
  –Paresthesias, jitteriness, seizures
  –Muscle cramping, tetany, carpal-pedal spasm
  –Cardiac disease, neck surgery
  –Autoimmune disorders, liver disease, renal disease

• Physical exam
  –Vital signs, growth parameters
  –Facial dysmorphism (DiGeorge syndrome, PHP IA)
  –Skeletal deformities (bowed legs, widened wrists/ankles, rachitic rosary, frontal bossing)
  –Cardiac exam (heart murmur with DiGeorge)
  –DTRs for hyperreflexia, carpal-pedal spasm
  –Chvostek sign (twitching of circumoral muscles after tapping on facial nerve in front of the ear)
  –Trousseau sign (carpal-pedal spasm after maintaining arm BP cuff 20 mmHg above systolic BP for 3 minutes)
  –Thrush, vitiligo, alopecia, nail fungal infection (for Blizzard)

• Labs: PTH, total and ionized calcium, vitamin D levels, alkaline phosphatase, LFT, BUN, Cr, magnesium, phosphorus, albumin; urine calcium and Cr
• ECG: Prolonged QT interval
• CXR: Absent thymus in DiGeorge
• Long bone films: Rachitic changes
• CT brain: Evaluate for calcification of basal ganglia

» READ BOOK EXCERPT ONLINE »

Source: In A Page: Pediatric Signs and Symptoms, 2007

HYPOCALCEMIA: Approach to the Diagnosis
(Differential Diagnosis in Primary Care)

Determining the serum phosphate and alkaline phosphatase levels will facilitate differentiating the causes of hypocalcemia. The phosphates and alkaline phosphatase are elevated in chronic nephritis but only the alkaline phosphatase is elevated in renal tubular acidosis and malabsorption syndrome. Only the phosphorus is elevated in hypoparathyroidism and pseudohypoparathyroidism. Hypoparathyroidism can be distinguished by a low serum PTH assay result.

» READ BOOK EXCERPT ONLINE »

Source: Differential Diagnosis in Primary Care, 2007

Chvostek's sign: History and physical examination
(Handbook of Signs & Symptoms (Third Edition))

Obtain a brief history. Find out if the patient has had his parathyroid glands surgically removed or if he has a history of hypoparathyroidism, hypomagnesemia, or a malabsorption disorder. Ask him or his family if they have noticed any changes in the patient's mental status, such as depression or slowed responses, which can accompany chronic hypocalcemia.

» READ BOOK EXCERPT ONLINE »

Source: Handbook of Signs & Symptoms (Third Edition), 2006

Carpopedal spasm: History and physical examination
(Handbook of Signs & Symptoms (Third Edition))

If the patient isn't in distress, obtain a detailed history. Ask about the onset and duration of the spasms and ask for a description of pain they produce. Also ask about related signs and symptoms of hypocalcemia, such as numbness and tingling of the fingertips and feet, other muscle cramps or spasms, and nausea, vomiting, and abdominal pain. Check for previous neck surgery, calcium or magnesium deficiency, tetanus exposure, and hypoparathyroidism.

During the history, form a general impression of the patient's mental status and behavior. If possible, ask family members or friends if they've noticed changes in the patient's behavior. Mental confusion or even personality changes may occur with hypocalcemia.

Inspect the patient's skin and fingernails, noting dryness or scaling and ridged, brittle nails.

» READ BOOK EXCERPT ONLINE »

Source: Handbook of Signs & Symptoms (Third Edition), 2006

Calcium imbalance: Diagnosis
(Professional Guide to Diseases (Eighth Edition))

Confirming diagnosis  A serum calcium level less than 8.5 mg/dl confirms hypocalcemia; a level more than 10.5 mg/dl confirms hypercalcemia. (However, because approximately one-half of serum calcium is bound to albumin, changes in serum protein must be considered when interpreting serum calcium levels. A common conversion formula is calcium corrected = calcium actual + 0.8 x [4.0 – albumin level]. Ionized calcium levels are 4.65 to 5.28 mg/dl and are a measure of the fraction of serum calcium in ionized form.)

The Sulkowitch urine test shows increased calcium precipitation in hypercalcemia. In hypocalcemia, an electrocardiogram (ECG) reveals lengthened QT interval, prolonged ST segment, and arrhythmias; in hypercalcemia, shortened QT interval and heart block. (See Diagnosing hypercalcemia, pages  916 and 917.)

» READ BOOK EXCERPT ONLINE »

Source: Professional Guide to Diseases (Eighth Edition), 2005

Chvostek's sign: History and physical examination
(Professional Guide to Signs & Symptoms (Fifth Edition))

Obtain a brief history. Find out if the patient has had the parathyroid glands surgically removed or if he has a history of hypoparathyroidism, hypomagnesemia, or malabsorption disorder. Ask him or his family if they have noticed any mental changes, such as depression or slowed responses, which can accompany chronic hypocalcemia.

» READ BOOK EXCERPT ONLINE »

Source: Professional Guide to Signs & Symptoms (Fifth Edition), 2006

Carpopedal spasm: History and physical examination
(Professional Guide to Signs & Symptoms (Fifth Edition))

If the patient isn’t in distress, obtain a detailed history. Ask about the onset and duration of the spasms and the degree of pain they produce. Also ask about related signs and symptoms of hypocalcemia, such as numbness and tingling of the fingertips and feet, other muscle cramps or spasms, and nausea, vomiting, and abdominal pain. Check for previous neck surgery, calcium or magnesium deficiency, tetanus exposure, and hypoparathyroidism.

During the history, form a general impression of the patient’s mental status and behavior. If possible, ask family members or friends if they’ve noticed changes in the patient’s behavior because hypocalcemia can cause confusion and even personality changes.

Inspect the patient’s skin and fingernails, noting any dryness or scaling and ridged, brittle nails.

» READ BOOK EXCERPT ONLINE »

Source: Professional Guide to Signs & Symptoms (Fifth Edition), 2006

Calcium imbalance: Diagnosis
(Handbook of Diseases)

A serum calcium level below 4.5 mEq/L confirms hypocalcemia; a level above 5.5 mEq/L confirms hypercalcemia. (However, because about half of serum calcium is bound to albumin, changes in serum protein must be considered when interpreting serum calcium levels.)

In patients with hypercalcemia, urine test results show an increase in urine calcium precipitation. In those with hypocalcemia, an electrocardiogram (ECG) reveals a lengthened QT interval, a prolonged ST segment, and arrhythmias; in those with hypercalcemia, an ECG reveals a shortened QT interval and heart block.

» READ BOOK EXCERPT ONLINE »

Source: Handbook of Diseases, 2003

Carpopedal spasm: History
(Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series)

Ask the patient about the onset and duration of the spasms and the degree of pain they produce. Assess him for related signs and symptoms of hypocalcemia, such as numbness and tingling of the hands and feet, other muscle cramps or spasms, and nausea, vomiting, and abdominal pain. Determine whether the patient’s history includes previous neck surgery, calcium or magnesium deficiency, tetanus exposure, or hypoparathyroidism.

Ask the patient’s family members whether they noticed changes in his behavior. Mental confusion — even personality changes — may occur with hypocalcemia.

Physical examination

Inspect the patient’s skin and fingernails, noting dryness or scaling and ridged, brittle nails. Obtain his vital signs. Perform a head-to-toe assessment with a complete respiratory assessment. Check Chvostek’s sign (tapping of the facial nerve, which results in facial nerve spasm).

» READ BOOK EXCERPT ONLINE »

Source: Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series, 2007

Chvostek's sign: History
(Signs & Symptoms: A 2-in-1 Reference for Nurses)

Obtain a brief history. Find out if the patient has had the parathyroid glands surgically removed or if he has a history of hypoparathyroidism, hypomagnesemia, or malabsorption disorder. Ask him or his family if they have noticed any mental changes, such as depression or slowed responses, which can accompany chronic hypocalcemia. Question the patient about tingling around the mouth and in the fingertips and feet.

» READ BOOK EXCERPT ONLINE »

Source: Signs & Symptoms: A 2-in-1 Reference for Nurses, 2007

Carpopedal spasm: History
(Signs & Symptoms: A 2-in-1 Reference for Nurses)

If the patient isn’t in distress, obtain a detailed history. Ask about the onset and duration of the spasms and the degree of pain they produce. Also ask about related signs and symptoms of hypocalcemia, such as numbness and tingling of the fingertips and feet, other muscle cramps or spasms, and nausea, vomiting, and abdominal pain. Check for previous neck surgery, calcium or magnesium deficiency, tetanus exposure, and hypoparathyroidism. Ask the patient if he had recent puncture wounds, and inquire about his immunizations.

During the history, form a general impression of the patient’s mental status and behavior. If possible, ask family members or friends if they have noticed changes in the patient’s behavior. Mental confusion or even personality changes may occur with hypocalcemia.

» READ BOOK EXCERPT ONLINE »

Source: Signs & Symptoms: A 2-in-1 Reference for Nurses, 2007

Chvostek's sign: History and physical examination
(Nursing: Interpreting Signs and Symptoms)

Obtain a brief history. Find out if the patient has had his parathyroid glands surgically removed or if he has a history of hypoparathyroidism, hypomagnesemia, or a malabsorption disorder. Ask him or his family if they have noticed changes in the patient's mental status, such as depression or slowed responses, which can accompany chronic hypocalcemia. Ask the patient if he has experienced any numbness and tingling in his fingers, toes, or around his mouth. Also ask him about muscle twitching or cramping.

» READ BOOK EXCERPT ONLINE »

Source: Nursing: Interpreting Signs and Symptoms, 2007

Carpopedal spasm: History and physical examination
(Nursing: Interpreting Signs and Symptoms)

If the patient isn't in distress, obtain a detailed history. Ask about the onset and duration of the spasms and ask for a description of pain they produce. Also ask about related signs and symptoms of hypocalcemia, such as numbness and tingling of the fingertips and feet, other muscle cramps or spasms, and nausea, vomiting, and abdominal pain. Check for previous neck surgery, calcium or magnesium deficiency, tetanus exposure, and hypoparathyroidism.

During the history, form a general impression of the patient's mental status and behavior. If possible, ask family members or friends if they've noticed changes in the patient's behavior. Mental confusion or even personality changes may occur with hypocalcemia.

Inspect the patient's skin and fingernails, noting dryness or scaling and ridged, brittle nails.

» READ BOOK EXCERPT ONLINE »

Source: Nursing: Interpreting Signs and Symptoms, 2007

HYPOCALCEMIA: Approach to the Diagnosis
(Differential Diagnosis in Primary Care)

Determining the serum phosphate and alkaline phosphatase levels will facilitate differentiating the causes of hypocalcemia. The phosphates and alkaline phosphatase are elevated in chronic nephritis, but only the alkaline phosphatase is elevated in renal tubular acidosis and malabsorption syndrome. Only the phosphorus is elevated in hypoparathyroidism and pseudohypoparathyroidism. Hypoparathyroidism can be distinguished by a low serum PTH assay result.

» READ BOOK EXCERPT ONLINE »

Source: Differential Diagnosis in Primary Care, 2007

 » Next page: Signs of Hypocalcemia

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