Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (621 page)

   Increased serum phosphorus. Phosphorus-to-creatinine ratio >3 indicates lactic acidosis either alone or as a component of other metabolic acidosis.

   WBC count is increased (occasionally to leukemoid levels).

   Increased serum uric acid is frequent (up to 25 mg/dL in lactic acidosis).

   Increased serum AST, LD, and phosphorus levels.

MIXED ACID–BASE DISTURBANCES

   Mixed acid–base disturbances must always be interpreted with clinical data and other laboratory findings.

   Respiratory Acidosis with Metabolic Acidosis

   Acidemia may be extreme with

   pH <7.0 (H
⁺
>100 mmol/L).

   HCO
₃
⁻
<26 mmol/L. Failure of HCO
₃
⁻
to increase ≥3 mmol/L for each 10 mm Hg rise in pCO
₂
suggests metabolic acidosis with respiratory acidosis.

   Examples: Acute pulmonary edema, cardiopulmonary arrest (lactic acidosis due to tissue anoxia and CO
₂
retention due to alveolar hypoventilation).

   Mild metabolic acidosis superimposed on chronic hypercapnia causing partial suppression of HCO
₃
⁻
may be indistinguishable from adaptation to hypercapnia alone.

   Respiratory Acidosis with Metabolic Alkalosis

   Decreased or absent urine chloride indicates that chloride-responsive metabolic alkalosis is a part of the picture.