Zinc-responsive nightblindness in sickle cell anemia
1982
Abnormalities of zinc (Zn) metabolism have been identified in homozygous subjects with sickle cell anemia. Recent study of experimental Zn deficiency in animals showed a reduction in retinol dehydrogenase, a potential Zn-metalloenzyme which indirectly assists rhodopsin formation, the visual pigment of rods in the retina. Other recent studies demonstrated that certain nightblind patients wiith alcoholic cirrhosis and Zn deficiency improved their in-dark adptation in response to oral Zn supplementation. A further study evaluated dark adaptation in a group of sickle cell disease patients. The neutrophil Zn content (but not plasma Zn) was significantly lower for patients with impaired dark adaptation. Longitudinal follow-up patients supplemented with Zn acetate daily improved their in-dark adaptability. Indications are that Zn deficiency at the level of retinal tissue can be responsible for retinal dysfunction in nightblind sickle cell anemia patients. (wz)
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