Serum concentrations of ionized calcium reflect renal function in patients with sarcoidosis
Hamada, K.; Nagai, S.; Shigematsu, M.; Nagao, T.; Hayaschi, M.; Tsutsumi, T.; Izumi, T.
Sarcoidosis Vasculitis and Diffuse Lung Diseases Official Journal of Wasog 19(1): 71-77
2002
ISSN/ISBN: 1124-0490 PMID: 12002390 Document Number: 547321
Decrease in renal function was investigated in relation to altered metabolism of calcium in patients with sarcoidosis. Fifty consecutive patients with pulmonary sarcoidosis (23 men and 27 women, 47 +/- 15 years as mean +/- SD) were studied on a daily diet consisting of 500 mg of calcium and 1000 mg of phosphorus. Renal functions were evaluated with Z scores of creatinine clearance (Ccr). Decreased renal function (Ccr Z score < -1) was detected in 13 out of 50 sarcoidosis patients (26.0%). In seven patients (14.0%) Ccr Z scores were less than -2; relative risk (RR) and 95% confidence interval (95% CI) were 13.9 and 2.97 to 64.7, respectively. Ccr Z score correlated most significantly with serum concentration of ionized calcium (sCa2+) (r = -0.574, 95% CI, -0.735 to -0.352, p < 0.0001). A stepwise regression analysis adjusting for observation time, serum concentration of calcium and 1,25-Dihydroxyvitamin D, urinary excretion of calcium, and urinary calcium crystals showed that sCa2+, together with angiotensin-converting enzyme activity in serum, was the most contributory variable to decrease in renal function in sarcoidosis patients (R2 = 0.391, p < 0.0001). A cutoff value of sCa2, 1.30 mmol/L obtained with a discriminant analysis showed 69.2% of sensitivity and 89.2% of specificity for decreased renal function. We reported increased prevalence of decreased renal function among sarcoidosis patients. sCa2+ was a significant index that reflected the alteration of renal function.