Zinc balance in combined zinc deficiency and uremia.
In order to evaluate whether the hypozincemia associated with chronic renal failure represents true negative zinc balance, male Lewis rats were randomized and pair-fed zinc replete (+Zn) or deplete (-Zn) diets. Subsequently, each animal underwent one- and two-thirds nephrectomy, or a sham operation. Complete balances for zinc, calcium, and magnesium were determined weekly before and after nephrectomy. At sacrifice, -Zn animals had significantly lower (P less than 0.005) plasma zinc levels compared to controls. Nephrectomized (N) animals had significantly elevated plasma creatinine (P less than 0.005), diminished creatinine clearances (P less than 0.005), and increased urinary flows (P less than 0.005) and protein excretion (P less than 0.01) compared to sham-operated (S) controls. Zinc nutritional status had no effect on these parameters in animals with comparable renal function. -Zn/N animals had consistently significantly elevated (P less than 0.005) urinary zinc excretion compared with -Zn/S with similar plasma zinc concentrations. Urinary zinc excretion correlated with urinary flow (r = 0.739, P less than 0.005), urinary protein (r = 0.635, P less than 0.01) and urinary calcium excretion (r = 0.855, P less than 0.005) in -Zn groups. -Zn/N rats had a significantly larger fecal zinc excretion for the first week post-nephrectomy, compared to -Zn/N controls (P less than 0.005). This resulted in negative zinc balance in -Zn/N animals, compared to their pre-nephrectomy balance (P less than 0.05) or to -Zn/S controls for the first (P less than 0.005) and second (P less than 0.05) weeks. -Zn/N rats had lower (P less than 0.02) hepatic zinc concentrations compared to the -Zn/S group.(ABSTRACT TRUNCATED AT 250 WORDS)