After initial promotion of copper excretion with D-penicillamine, the effect of oral zinc sulphate (3 x 150 mg/day, loading dose; 3 x 100 mg/day, maintenance dose) in two children with clinically stable Wilson's disease was evaluated after completion of three years' treatment. The course, judged by clinical, biochemical, and histological parameters was satisfactory in both. The urinary copper concentration reverted to less than 1.26 ~mo1/24 hours; and the serum copper concentration decreased further during zinc sulphate treatment. In one child the rise in 24 hour urinary copper excretion observed after a challenge dose of D-penicillamine (220 mg/kg) remained constant throughout the period of observation while the liver copper content fell from 1460 pg/g dry weight to 890 pg/g dry weight. In the other patient, however, the liver copper content as well as the 24 hour urinary copper excretion increased after D-penicillamine challenge during the third year of treat men t .
We conclude that zinc sulphate is a low toxic and well tolerated alternative for D-penicillamine. The dosage depends, however, on individual factors not yet well understood, and we recommend restriction of its use to patients who do not tolerate mpenicillamine well. We suggest monitoring of treatment with yearly D-penicillamine challenge and a liver biopsy if liver function deteriorates.