Hypercalciuria, hyperoxaluria, and hypocitraturia screening from random urine samples in patients with calcium lithiasis.

Calcium lithiasis is the most frequently diagnosed renal lithiasis and is associated with a high percentage of patients with metabolic disorders, such as hypercalciuria, hypocitraturia, and hyperoxaluria. The present study included 50 patients with recurrent calcium lithiasis. We conducted a random urine test during nocturnal fasting and a 24-h urine test, and examined calcium, oxalate, and citrate. A study of the linear correlation between the metabolites was performed, and the receiver operator characteristic (ROC) curves were analyzed in the random urine samples to determine the cutoff values for hypercalciuria (excretion greater than 200 mg), hyperoxaluria (excretion greater than 40 mg), and hypocitraturia (excretion less than 320 mg) in the 24-h urine. Linear relationships were observed between the calcium levels in the random and 24-h urine samples (R = 0.717, p = 0.0001), the oxalate levels in the random and 24-h urine samples (R = 0.838, p = 0.0001), and the citrate levels in the random and 24-h urine samples (R = 0.799, p = 0.0001). After obtaining the ROC curves, we observed that more than 10.15 mg/dl of random calcium and more than 16.45 mg/l of random oxalate were indicative of hypercalciuria and hyperoxaluria, respectively, in the 24-h urine. In addition, we found that the presence of less than 183 mg/l of random citrate was indicative of the presence of hypocitraturia in the 24-h urine. Using the proposed values, screening for hypercalciuria, hyperoxaluria, and hypocitraturia can be performed with a random urine sample during fasting with an overall sensitivity greater than 86%.