Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1284 page)

   Disseminated TB

   Hypothyroidism

   Infantile blindness

   Liver, GI, or pancreatic disease

   Night blindness

   Protein malnutrition

   Sterility and teratogenesis

   Zinc deficiency

   Limitations

   Alcohol (moderate intake), oral contraceptives, and probucol increase vitamin A levels.

   Alcohol (chronic intake, alcoholism), allopurinol, cholestyramine, colestipol, mineral oil, and neomycin decrease vitamin A levels.

   Serum retinol is typically maintained until hepatic stores are almost depleted. Values >0.30 mg/L represent adequate liver stores, whereas values <0.10 mg/L indicate deficiency.

   Samples that come in contact with plastic tubing or have been exposed to excessive light may show low results.

VITAMIN A RELATIVE DOSE–RESPONSE (RDR) TEST

   Definition