Hyperpigmentation in pernicious anemia
1979
The melanosome is a pigment-containing organelle within the melanocyte responsible for coloration in human skin. Its synthesis is dependent on the presence of tyrosine and tyrosinase; abnormalities in this process can cause hyperpigmentation and is frequently seen in cases of pernicious anemia of autoimmune etiology or deficiency of vitamin B12 or folate from dietary causes. In 3 case studies of black women, symptoms of general weakness, fatigability, anorexia, mental confusion, and patches of hyperpigmentation were present. Blood hemoglobin was 6-7 g/dl. Serum B12 was low. All 3 had gastric achlorhydria. Treatment with vitamin B12 alleviated both anemia and hyperpigmentation within 2 months. The excessive production of melanin in this condition as well as in non-tropical sprue and chronic liver disease may be due to one of several reasons: a metabolic block which raises tyrosine levels in the blood; alteration of glutathione metabolism reflected in tyrosinase activity; elevated biopterin levels; and lack of thymidine, which impairs DNA synthesis and may divert tyrosine, among other amino acids, from its usual pathway.
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