| History Subclinical forms of VAD 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 VAD anemia. Physical Signs and symptoms include Bitot spots, poor dark adaptation (nyctalopia), dry skin, dry hair, pruritus, broken fingernails, keratomalacia, xerophthalmia, and follicular hyperkeratosis (phrynoderma) secondary to blockage of hair follicles with plugs of keratin. Other signs include excessive deposition of periosteal bone secondary to reduced osteoclastic activity, anemia, and keratination of mucous membranes. Causes The risk of VAD is increased in patients with fat malabsorption, cystic fibrosis, sprue, pancreatic insufficiency, IBD, cholestasis, and/or small-bowel bypass surgery. It is also increased in vegans, refugees, recent immigrants, persons with alcoholism, and toddlers and preschool children living below the poverty line. These patients should be advised to consume vitamin A. |
| From the work of Weston Price, we can assume that the amount in Quote:
|
| The liver is the main storage organ for vitamin A in humans (1); thus, the best way to assess vitamin A status is to measure hepatic stores. Because direct measurement of hepatic vitamin A is not feasible under normal circumstances, various indirect methods are used to assess vitamin A status (2). Among these, the only method that gives a quantitative measure of total body stores is an isotope dilution procedure that involves 1) administration of an oral dose of deuterated vitamin A, 2) determination of isotopic ratios of retinol in serum after the isotope has equilibrated with the body's vitamin A pool, and 3) application of the mathematical formula of Furr et al (3) to calculate total body stores of vitamin A. This formula, which is a modification of the formula developed by Bausch and Rietz (4), has been used successfully in adults (3, 5). The deuterated-retinol-dilution (DRD) technique for assessing body stores was validated by Furr et al (3) in generally healthy, adult American surgical patients and by Haskell et al (5) in adult Bangladeshi surgical patients with low to adequate vitamin A status. In these 2 studies, generally good agreement was found between the calculated values and values obtained directly through liver biopsies; the correlation coefficients were 0.88 (3) and 0.75 (5). |
