Altered calcium metabolism: the probable major biochemical lesion in many pathological and clinical states of lead toxicity

Abstract

The study was designed to provide evidence for altered calcium metabolism in lead toxicity and its pathological and clinical implications, which are incompletely elucidated in humans. Eighty-six lead (Pb) workers and 51 age, sex, dietary and anthropometric indices matched controls participated in this study. Blood lead level (BLL), serum total and ionized calcium, inorganic phosphate, serum albumin, total alkaline phosphatase (ALP) and the Bone form (isoenzyme) of alkaline phosphatase (B- ALP) and indices of renal function were evaluated in both lead workers and controls. The result showed blood lead level was higher in Pb workers than in controls (P<0.001), total and ionized calcium in contrast were significantly lower in Pb workers than in controls (P<0.01, P<0.001) respectively. Inorganic phosphate though higher in Pb workers was not significantly different (P>0.05). Both ALP and B-ALP were similar in lead workers than in controls (P>0.05, P>0.05) respectively. Nineteen percent (19%) of Pb workers demonstrated calcium level below the lower limit of reference range (<8.5mg/dl) while only 4% of the controls exhibited similar levels. Creatinine and urea were similar in Pb workers and controls (P>0.05; P>0.05) respectively. Urinary protein related to creatinine was significantly higher in Pb workers than in controls (P<0.001). Serum albumin and urinary microalbumin levels were also similar in both groups (P>0.05; P>0.05) respectively. These data are suggestive of altered calcium metabolism impairing cell membrane stabilization, the vasorelaxing effect of calcium and cell signaling. Altered calcium metabolism may be the major biochemical lesion underlying many pathological and clinical states of lead toxicity.

Journal of Biomedical Investigation Vol. 5 (1) 2007: pp. 9-16