Vitamin A

Keywords: Retinol

Specimen:

5 mL blood in plain tube. Protection from light by covering tube with foil is essential.

Method:

HPLC.

Reference Interval:

0.7-2.8 µmol/L.

Application:

Suspected vitamin A deficiency in patients with malabsorption or dietary deficiency.

Suspected vitamin A toxicity eg, inappropriate vitamin A therapy.

Interpretation:

High levels (vitamin A toxicity) may be missed if the method is unable to detect vitamin A esters.

High levels occur in renal failure (due to elevated plasma retinol binding protein), but this is not associated with toxicity.

Low levels are found with fat malabsorption.

Dietary deficiency is very rare in developed countries.

Reference:

Tee ES. Crit Rev Food Sci Nutr 1992; 31:103-163.