Treatment of Wilson's disease with zinc. XIII: Therapy with zinc in presymptomatic patients from the time of diagnosis.

The siblings of patients with newly diagnosed Wilson's disease are each at 25% risk of also having this autosomal recessive disease. Screening these siblings allows their detection and institution of prophylactic therapy before they become clinically ill. Herein we report the successful treatment of 13 presymptomatic patients with zinc acetate. These patients who received zinc have been followed for 3 to 9 years. In well-complying patients, 24-hour urine copper and non-ceruloplasmin plasma copper levels have decreased over years of follow-up, consistent with the elimination of the excess easily mobilized copper (the potentially toxic copper) of the body. Effect of therapy and compliance are easily monitored by following 24-hour urine zinc and copper levels. The urine copper level is a good reflection of the body's excess load of easily mobilizable copper. It will increase if control is not adequate. A decrease in urine zinc is an early signal that the patient's compliance is not optimal. The levels of hepatic copper in response to several years of zinc therapy may remain the same, go down, or go up temporarily. This is a reflection of zinc induction of hepatic metallothionein, which sequesters copper in a non-toxic pool. Hepatic copper levels should not be used to manage therapy. Liver function is well preserved by zinc therapy, and no zinc toxicity occurred in these 13 patients. No patient developed symptoms related to Wilson's disease. We conclude that zinc acetate is a fully effective and non-toxic therapy for the prophylactic treatment of the presymptomatic Wilson's disease patient.