Biological Indices for Early Detection of Cadmium Poisoning: Significance of Urinary Metallothionein

Park, Jung Duck; Hong, Yeon Pyo; Chang, Im Won

Abstract

Metallothionein(MT) is a low molecular weight protein that is induced as a defence mechanism for cadmium (Cd) toxicity. In present study, urinary MT was determined using a competitive ELISA in Cd-exposed rats. In addition, measures the urinary, blood and renal Cd concentration and the urinary excretion of total protein, beta 2-microglobulin (MG) and N-acetyl-beta-D-glucosaminidase(NAG) at 1, 3, 7, 14, 28 days after Cd injection in Cd-exposed rats with dosers of 0.8 and 1.6 mg Cd/kg body weight respectively. The urinary, blood and renal Cd were specific for Cd-exposure, that increased in proportional to dose of Cd. The urinary and blood Cd tended to slightly decrease, while renal Cd tended to increase by lapse of time after Cd exposure. this finding indicates that renal Cd is more specific than urinary and blood Cd for Cd exposure. The urinary excretion of MT showed a statistically significant increase in Cd exposed rats(0.8 and 1.6 no Cd/kg body weight). The increase of urinary excretion of MT was more evident at 7, 14, 28 lays after Cd exposure than the changes of urinary excretion of total protein, beta-MG and NAG. The Pearson's correlation coefficients between urinary Cd and urinary MT, beta-MG, NAG and total protein were 0.4344, 0.3727, 0.3307 and 0.2099, respectively. These findings indicate that the urinary MT is more sensitive and specific than total protein, beta-MG and NAG for Cd exposure. The present results suggest that the urinary MT, using a simple and rapid competitive ELISA, is a valuable index as screening test in epidemiologic study for Cd exposed group.