Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1075 page)

   Evaluation of methylmalonic academia in children.

   Evaluation of megaloblastic anemia (cobalamin deficiency). Serum MMA may be a more reliable marker of cobalamin deficiency than direct cobalamin determination.

   Interpretation

Increased In

   Vitamin B
₁₂
deficiency

   Pregnancy

   Cobalamin genetic defects

   Methylmalonic acidemia

   Limitations

   Serum and urine levels are more reliable markers of cobalamine deficiency than direct cobalamine determination.

   Diet, nutritional status, and age should be considered in the evaluation of serum MMA level.

METYRAPONE TEST

   Definition

   The metyrapone stimulation test is based on the principle that decreasing serum cortisol concentrations is expected to produce an increase in ACTH secretion.

   Use