ABSTRACT
BACKGROUND: Urinary copper excretion higher than 100 µg/24 h is useful for diagnosing Wilson's disease. d-Penicillamine challenge test may produce higher levels than 1400 µg/24 h, allowing for better diagnostic accuracy. This study investigated whether heterozygotes reach this value and compared copper serum levels, ceruloplasmin, and urinary copper excretion before and after administering d-penicillamine to the parents of Wilson's disease patients. METHODS: Fifty parents of adult patients were enrolled to obtain copper serum levels and ceruloplasmin along with 24-h urinary copper excretion before and after administering 1g d-penicillamine. RESULTS: Serum ceruloplasmin and copper levels were significantly lower in fathers than in mothers (mean 21.8×27.8 mg%; 71.4×88.0 µg%; p ≤ 0.001). The mean of basal 24-h urinary copper excretion was higher in fathers (26.2×18.7 µg/24 h, p=0.01), but did not differ between the genders after d-penicillamine (521.7×525.3, range 31.6-1085.1 µg/24h, p=0.8). CONCLUSIONS: The mean values of serum copper, ceruloplasmin, and basal urinary copper excretion were different between males and females. The current diagnostic threshold of 24-h urinary copper excretion after d-penicillamine was not reached by heterozygotes. The increased urinary copper excretion after d-penicillamine challenge was much higher than fivefold the upper limit of normal urinary copper excretion in the majority of heterozygotes and should not be taken into account when diagnosing Wilson's disease.