An evaluation of test sticks used for the measurement of the specific gravity of urine from patients with stone disease.

A test stick for the measurement of the SG of the urine of stoneformers was examined. In 230 spontaneously voided urines and 45 25 h-urines the SG was measured by the test stick and compared with urinometer measurements. The two methods showed a good correlation (r = 0.86). Due to the principle of reaction of the SG-teststick a direct relationship of the SG-values to the sodium concentration and to the ionic strength of urine was found. There is no correlation between the relative supersaturation of CaOx and the SG-determination (urinometer, test stick). The handling of the SG-test stick is simple and can be easily performed by the patient.