Subclinical forms of vitamin A deficiency may not cause any symptoms, but the risk of developing respiratory and diarrheal infections is increased, the growth rate is decreased, and bone development is slowed. Patients may have a recent history of increased infections, infertility secondary to impaired spermatogenesis, or recent spontaneous abortion secondary to impaired embryonic development. The patient may also report increased fatigue, as a manifestation of vitamin A deficiency anemia.
Pregnant women do not require increased vitamin A supplementation. In fact, the Teratology Society advocates that women be informed of the possible risk for cranial neural crest defects and other malformations resulting from excessive use of vitamin A shortly before or during pregnancy.
A serum RBP study is easier to perform and less expensive than a serum retinol study, because RBP is a protein and can be detected by an immunologic assay. RBP is also a more stable compound than retinol with respect to light and temperature. However, RBP levels are less accurate, because they are affected by serum protein concentrations and because types of RBP cannot be differentiated.
A Cochrane Review article included 43 randomized trials representing 215,633 children, and provided strong support for the importance of vitamin A supplementation in preventing childhood mortality in children from 6 months to 5 years of age. No evidence suggests that vitamin A supplementation reduces mortality and morbidity among children aged 1-6 months.
For more on vitamin A deficiency, read here.
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Cite this: Romesh Khardori. Fast Five Quiz: Test Yourself on Various Nutritional Deficiencies - Medscape - Apr 10, 2017.