Urine Electrolytes and Osmolality
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þ Urine Osmolality
 - approximated from specific gravity by:
   (S.G. - 1) * 40 = osmolality in Osmoles
   examples:
   S.G. = 1.030
   (S.G. - 1) = .030
   (S.G. - 1) * 40 = 1.2 Osm
   S.G. = 1.007
   (S.G. - 1) = .007
   (S.G. - 1) * 40 = .28 Osm

þ Interpreting Urine Na+
  (quick and dirty)
 - Volume Depletion: 0-10 mEq/L = Extrarenal Loss; >10 = renal salt wasting or
   adrenal insufficiency
 - Acute Oliguria: 0-10 mEq/L = "prerenal azotemia"; >30 = ATN
 - Hyponatremia: 0-10 mEq/L = volume depletion or edematous states

þ Interpreting Urine K+
  (quick and dirty)
 - Hypokalemia:  0-10 mEq.L = extrarenal K+ loss; >10 = renal K+ loss

þ Interpreting Urine Cl-
 - Metabolic Alkalosis:  0-10 mEq/L = "chloride-responsive" alkalosis; ~=
   dietary intake = "chloride-resistant" alkalosis