Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1096 page)

   May be used with urinalysis when patient has had radiopaque substances, has glycosuria, or proteinuria

   Evaluate dehydration, amyloidosis. Osmolality is desirable in examination of neonatal urine when protein or glucose is present.

   Interpretation

Increased In

   Hyperglycemia

   DKA (osmolality should be determined routinely in grossly unbalanced diabetic patients)

   Nonketotic hyperglycemic coma

   Hypernatremia with dehydration

   Diarrhea, vomiting, fever, hyperventilation, inadequate water intake

   Diabetes insipidus—central

   Nephrogenic diabetes insipidus—congenital or acquired (e.g., hypercalcemia, hypokalemia, chronic renal disease, sickle cell disease, effect of some drugs)

   Osmotic diuresis—hyperglycemia, administration of urea or mannitol

   Hypernatremia with normal hydration—caused by hypothalamic disorders

   Insensitivity of osmoreceptors (essential hypernatremia)—water loading does not return serum osmolality to normal; chlorpropamide may lower serum sodium toward normal