Urinary excretion of zinc, copper and iron in the streptozotocin-diabetic rat

Abstract

The influence of the chemically diabetic condition on urinary excretion of zinc, copper and iron was investigated. Male Sprague-Dawley rats were injected with streptozotocin to induce insulin-dependent diabetes (day 0) and 24-hour urinary collections taken 1, 4, 7, 10 and 14 days later. Onset of the diabetic condition was correlated with a rapid and persistent increase in the amounts of the three trace metals excreted daily in the urine. Diabetic rats excreted 3.4-, 5.0- and 4.9-fold more zinc, copper and iron, respectively, than controls in the urine on day 14. Insulin treatment of diabetic rats significantly reduced the quantities of the micronutrients excreted in urine, suggesting that altered hormonal status was the primary cause of increased urinary losses. Enhanced urinary output of the metals was not associated with reduction in the plasma, liver and kidney contents of zinc, copper and iron. Urinary trace metal excretion was correlated with food ingestion and urinary volume with greater amounts lost during the dark period for control and diabetic animals. The influence of endocrine status on urinary excretion of trace metals is discussed.