Diagnosis of Dehydration
Dehydration Diagnosis: Book Excerpts
Diagnosis of Dehydration: medical news summaries:
The following medical news items
are relevant to diagnosis and misdiagnosis issues for Dehydration:
Diagnostic Tests for Dehydration: Online Medical Books
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for more information about diagnostis of Dehydration.
HYPERNATREMIA:
Ask the Following Questions:
(Algorithmic Diagnosis of Symptoms and Signs)
- What is the chloride level? Hypernatremia with an elevated chloride is almost certainly due to dehydration, but renal and hypothalamic diabetes insipidus, heat exhaustion, and hypertonic fluid administration may also be responsible. A low chloride level with hypernatremia may be seen in aldosteronism or Cushing's syndrome.
- What is the serum
antidiuretic hormone
(
ADH)
assay? If this is low or absent, hypothalamic diabetes insipidus must be considered. If this is normal, one should consider dehydration, heat exhaustion, prolonged vomiting, renal diabetes insipidus, and hypertonic saline administration likely causes.
DIAGNOSTIC WORKUP
The workup should include a CBC, urinalysis, chemistry panel, serum and urine osmolality, plasma cortisol, serum ADH, plasma volume studies, serial electrolytes, and consultation with an endocrinologist or nephrologist.
» READ BOOK EXCERPT ONLINE »
Source: Algorithmic Diagnosis of Symptoms and Signs, 2003
Hypernatremia:
Differential Diagnosis
(In a Page: Signs and Symptoms)
- Increased water loss
–GI losses (diarrhea, vomiting, intestinal fistula)
–Drugs (e.g., diuretics, alcohol, amphotericin B, phenytoin, propoxyphene, lithium, demeclocycline)
–Sweating
–Burns
–Fever
–Hyperventilation
–Diabetes insipidus (central versus
nephrogenic)
–Severe burns
–Alcohol use
–Hyperglycemia (resulting in osmotic
diuresis)
–Diuresis phase of acute renal failure
–Peritoneal dialysis
–Thyrotoxicosis
–Hyperthermia
–Adrenal or renal failure
- Decreased water intake
–Poor oral intake (e.g., in the elderly)
–Inability to swallow water due to physical
limitation (e.g., coma, access/mobility problems, swallowing problems)
–Inability to recognize the need for water
due to a hypothalamic lesion (e.g., CVA)
–Impaired thirst
–Inappropriate IV fluids (e.g., renal failure)
–Tube feeding with inadequate free water
- Excessive sodium intake
–Endocrine causes: Cushing's syndrome, ectopic ACTH, primary aldosteronism
–Iatrogenic (e.g., inappropriately administered hypertonic saline, administration of sodium bicarbonate)
–Sea water ingestion/drowning
-
Renal salt retention
–Mineralocorticoid excess (Conn's
syndrome)
–Cushing's syndrome
–Congenital adrenal hyperplasia
–Multiple myeloma
–Sjögren's syndrome
Essential hypernatremia (reset osmostat)
Workup and Diagnosis
-
Hypernatremia is defined as serum Na+>145 mEq/L; however, clinical signs and symptoms generally do not appear until serum Na+>158 mEq/L
–Severity of symptoms relates to both the acuity and magnitude of rise in Na+
History should include questions about changes in thirst and urination, recent CNS surgery, administration of IV fluids, and history of mental status changes, seizures, polyuria, thirst, diarrhea, or vomiting
Initial laboratory studies include electrolytes, BUN, creatinine, magnesium, calcium, serum and urine osmolarity, and urine Na+
–BUN/creatinine are elevated with diuretic use, glycosuria, fluid loss (e.g., GI, respiratory, skin), impaired thirst, adrenal deficiency, and DI
–Normal in hyperaldosteronism (e.g., Conn's, Cushing's, CAH)
- Assess urine osmolality
–Hyperosmolar urine (i.e., when the kidney reaction to hypernatremia is the excretion of a minimal volume of urine that is maximally concentrated) suggests an extrarenal etiology of the hypernatremia
–Urine osmolarity is decreased in renal losses (e.g., diuretics and DI) and increased in GI, respiratory, and skin losses or poor intake
- Urine Na+is elevated in renal losses (>20 meq/L); decreased in GI, respiratory, and skin losses or poor intake (<10 meq/L); and normal in hyperaldosteronism
>
» READ BOOK EXCERPT ONLINE »
Source: In a Page: Signs and Symptoms, 2004
Hypernatremia:
Differential Diagnosis
(In A Page: Pediatric Signs and Symptoms)
-
Dehydration
–GI losses, especially watery diarrhea or profuse vomiting (very common)
–Impaired oral intake and inability to respond to normal thirst mechanisms (e.g., young infants, altered mental status, or iatrogenic administration of IV fluids)
-
Central diabetes insipidus (DI)
–Decreased or absent production of ADH
–Idiopathic
–Head trauma
–Suprasellar or infrasellar tumors
–Langerhans cell histiocytosis
–Granulomatous disease (including
tuberculosis, Wegener granulomatosis and
sarcoidosis)
–Infection
–Cerebral hemorrhage
-
Nephrogenic DI (NDI)
–Inability to respond to ADH
–Primary (congenital abnormality)
–Secondary (acquired renal tubular
dysfunction, e.g., progressive renal insufficiency; medications, e.g., lithium)
-
Severe skin or other insensible losses
–Excessive sweating
–Persistent rapid breathing
–Burns
-
Increased total body sodium (rare in children)
–Salt intoxication from
–Sodium chloride tablets
–IV NaCl or NaHCO3
–Breast milk after significant maternal
sodium load
–Concentrated formula
–Primary hyperaldosteronism
Workup and Diagnosis
-
History
–Vomiting, diarrhea
–Poor oral intake, recurrent dehydration
–Medications or salt supplementation
–Bicarbonate administration
–Burns
–Renal disease
-
Symptoms
–Lethargy, seizures, coma
–Polyuria, polydipsia
–Headache, vision changes
-
Family history
–Recurrent dehydration or early infant death (NDI)
-
Physical exam
–Blood pressure
–Assessment of hydration status (pulse, perfusion)
–Midline defects (suggests presence of pituitary/hypothalamic defects/central DI)
–Funduscopic exam
-
Labs
–Chemistry panel
–Serum osmolarity
–Urinalysis
–Urine osmolarity
-
Additional evaluation based on the clinical situation
–Water deprivation test (to evaluate for central vs
nephrogenic DI)
–CT or MRI of the head
» READ BOOK EXCERPT ONLINE »
Source: In A Page: Pediatric Signs and Symptoms, 2007
HYPERNATREMIA:
Approach to the Diagnosis
(Differential Diagnosis in Primary Care)
Dehydration can be diagnosed clinically by the tenting of the skin, mushy eyeballs, and concentrated urine. Laboratory work up includes serial electrolytes, chemistry panel, serum and urine osmolality, serum ADH, plasma renin, 24-hour urine aldosterone level, and consultation with an endocrinologist or a nephrologist. It is wise to withhold all noncritical drugs until a diagnosis is certain.
» READ BOOK EXCERPT ONLINE »
Source: Differential Diagnosis in Primary Care, 2007
HYPERNATREMIA:
Approach to the Diagnosis
(Differential Diagnosis in Primary Care)
Dehydration can be diagnosed clinically by the tenting of the skin,
mushy eyeballs, and concentrated urine. Laboratory workup includes serial
electrolytes, chemistry panel, serum and urine osmolality, serum ADH, plasma
renin, 24-hour urine aldosterone level, and consultation with an
endocrinologist or a nephrologist. It is wise to withhold all noncritical
drugs until a diagnosis is certain.
» READ BOOK EXCERPT ONLINE »
Source: Differential Diagnosis in Primary Care, 2007
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