A zinc tolerance test.

Abstract

Abstract Zinc sulfate, at 220 mg dosage, was given by mouth to 16 control subjects and a group of 16 patients with alcoholic cirrhosis to compare the increase in serum zinc and evaluate the urinary zinc excretion. The medication was given when the subjects were fasting. Blood was drawn at 0, 2, 4, and 6 hr, and urine was collected for a 24 hr period prior to and following the ingestion of zinc. In control subjects taking the 220 mg zinc sulfate dosage, serum zinc rose from 99 μ g/dl to a peak of 280 μ g/dl at 2 hr and was 145 μg/dl at 6 hr. Urine zinc excretion was increased over the pre-zinc values. Cirrhotic patients had lower fasting zinc levels and exhibited much less increase at 2 and 4 hr. The fasting mean value of 54 μg/dl increased to 98 μg/dl, and at the 6 hr period the serum zinc had returned to the fasting level. Urinary excretion was increased if pre-zinc excretion was normal but remained unchanged if the pre-zinc specimen contained large amounts of zinc. Nine postsurgical patients with delayed healing were similarly studied. The fasting serum zinc levels were normal. Following the zinc sulfate, minimal increases were noted during 6 hr, and there was no appreciable evidence of increased urinary zinc excretion. In each group the copper, calcium, and magnesium levels remained essentially constant during the period of increased serum zinc levels. A zinc tolerance determination of this kind may be of value in differentiating clinical entities in which zinc deficiency may occur.