Zinc deficiency: a cause of abnormal dark adaptation in cirrhotics.
Six stable alcoholic cirrhotics with serum zinc less than 70 microgram/100 ml had abnormal dark adaptation responses (mean dark adapted final threshold 3.2 +/- 0.6 versus 2.1 +/- 0.2 log lux in 21 age matched controls, P less than 0.01). Serum vitamin A ranged from 15 to 37 microgram/100 ml. Zinc sulfate (220 mg/day) was fed to three patients for 1 to 2 weeks and dark adapted final thresholds fell 0.9, 0.4, and 1.2 log lux without concurrent rises in serum vitamin A. Two patients were treated initially with oral vitamin A (10,000 IU/day) for 2 to 4 weeks, but their final thresholds fell to normal (2.1, 2.2 log lux) only after the addition of zinc for 1 to 2 weeks. The sixth patient, treated with vitamin A and zinc together, attained a normal final threshold in 2 weeks. The improvement in dark adaptation by zinc may be due to enhanced activity of previously depressed retinol dehydrogenase.
D000368:Aged; D003623:Dark Adaptation / Q000187:drug effects*; D006801:Humans; D008104:Liver Cirrhosis, Alcoholic / Q000150:complications / Q000503:physiopathology*; D008875:Middle Aged; D012160:Retina / Q000378:metabolism; D014786:Vision Disorders / Q000209:etiology*; D014801:Vitamin A / Q000378:metabolism* / Q000627:therapeutic use; D015032:Zinc / Q000172:deficiency* / Q000627:therapeutic use
D014801:Vitamin A; D015032:Zinc