Dermatologic Manifestations of Vitamin A Deficiency Workup

Updated: Mar 26, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: William D James, MD  more...
  • Print

Laboratory Studies

The diagnosis should be suspected in children who are malnourished or in patients with predisposing factors for its development. Note the following:

  • Serum vitamin A levels: The biochemical definition of vitamin A deficiency (VAD) is a plasma level of 35 µmol/dL or less. Several techniques are available, but high-pressure liquid chromatography is the most reliable. An important factor is that, with protein deficiency, serum vitamin A levels may be decreased despite good vitamin A intake and adequate vitamin A stores.

  • Total and holo retinol-binding protein (RBP) test: These tests (complex of vitamin A and RBP) for serum RBP tend to correlate with measures of serum vitamin A. These levels can also be decreased in the presence of protein deficiency.

  • Conjunctival impression cytology: This is a technique useful for detecting preclinical xerophthalmia. It is a noninvasive method of obtaining a specimen to assess the histologic appearance of the superficial conjunctival layers. Squamous metaplasia is evident by the presence of enlarged, irregular, and keratinized epithelial cells and the loss of goblet cells. Results are closely correlated with baseline serum vitamin A levels and with clinical improvement after treatment.