Effects of long-term zinc treatment in Japanese patients with Wilson disease: efficacy, stability, and copper metabolism

Wilson disease is an autosomal recessive disorder with copper metabolism. In Japan, the standard treatment is the administration of copper chelating agents, such as D-penicillamine and trientine. In this study, the authors used zinc acetate to treat Japanese patients with Wilson disease and investigated its efficacy. The 37 patients that comprise this study were found to have Wilson disease using clinical and biochemical tests and were administrated zinc acetate for 48 weeks. The authors followed the clinical symptoms and laboratory findings of the patients by assessing their complete blood counts, biochemical findings, as well as the results of urinalysis and special laboratory tests for copper and zinc metabolism. We also examined side effects of the treatment. Zinc acetate did not aggravate the hepatic or neurological symptoms of any of the patients. Blood biochemical analysis also did not reveal elevation of alanine aminotransferase, aspartate aminotransferase, and γ-glutamyltranspeptidase levels. Zinc treatment did not aggravate the patients' clinical signs and/or laboratory findings. However, it did improve some clinical symptoms of the Wilson disease patients. Although this agent had some side effects, none of them were severe. The authors measured spot urinary copper excretion, which gave an indication of the efficacy of treatment and of the sufficient dosage of zinc. We recommend maintaining a spot urinary copper excretion less than 0.075-μg/mg creatinine. The authors conclude that zinc acetate is an effective and safe treatment for Japanese patients with Wilson disease.