       Document 0430
 DOCN  M9640430
 TI    Challenging consults: application of principles of physiology and
       biochemistry to the bedside. Osmotic diuresis: the importance of
       counting the number of osmoles excreted.
 DT    9604
 AU    Levin A; Klassen J; Halperin ML; Renal Division, St. Paul's Hospital,
       University of British; Columbia, Vancouver.
 SO    Clin Invest Med. 1995 Oct;18(5):401-5. Unique Identifier : AIDSLINE
       MED/96120813
 AB    Polyuria is usually the result of a water diuresis or an osmotic
       diuresis. Traditionally, the assessment of the extracellular fluid (ECF)
       volume and the concentration of Na+ in plasma is sufficient to
       differentiate between the two. We present a case and our approach, which
       is based on calculations and quantitation of osmoles, to demonstrate the
       utility of this approach. A patient with diabetes mellitus, human T-cell
       lymphocyte virus, type 1 (HTLV-1) associated lymphoma, and hypercalcemia
       presented with marked ECF volume contraction and polyuria. A spot urine
       osmolality was 567 mOsm/kg H2O in the face of urine output of
       approximately 6 L/d. The initial diagnosis was an osmotic diuresis.
       However, a quantitative analysis revealed the enormous number of osmoles
       could not be accounted for physiologically. Hence, we postulated a water
       diuresis to be the cause of the polyuria. To confirm this hypothesis, we
       found that at different times during his hospitalization, the urine
       specific gravity ranged from 1.005 to 1.022, and urine output varied
       markedly over 8-h periods. Despite a plasma sodium of 147 mmol/L, the
       patient did not complain of thirst. Taken together, this suggested the
       presence of a hypothalamic lesion which caused central diabetes
       insipidus with variable output of antidiuretic hormone together with a
       blunted thirst response. Illustration of the utility of a quantitative
       approach to polyuria is the focus of the discussion.
 DE    Case Report  Chlorides/URINE  Diabetes Mellitus/COMPLICATIONS/URINE
       *Diuresis  Extracellular Space  Human  Hypercalcemia/COMPLICATIONS/URINE
       Leukemia-Lymphoma, T-Cell, Acute, HTLV-I-Associated/COMPLICATIONS/
       URINE  Male  Middle Age  *Osmolar Concentration
       Polyuria/ETIOLOGY/*URINE  Potassium/URINE  Sodium/BLOOD/URINE  Specific
       Gravity  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

