Investigation of Optimum pH and Temperature for In-Vitro Crystallization of Urinary Cystine

Abstract

Cystinuria contributes in formation of urinary stones. But, it has been reported that cystinuria is diagnosed when someone experiences with cystine stones. Therefore, early diagnosis of this condition is important. Thus, the objective of the study was to determine the optimum pH and temperature for crystallization of urine cystine in-vitro. Cystinuria solutions were prepared with the concentrations of 40, 60, 70, 75, 80, 90, 100 and 120 mg/dL. The pH of each solution was changed with the addition of acetic acid. Then solutions were exposed to temperature +4°C and 37°C, for 15, 30 and 45min. The sediments were observed microscopically for cystine crystals formation. Then acetone was added to cystinuria with the ratio of cystinuria:acetone, 8:1, 4:1, 2:1 and 1.1 and pH was altered with acetic acid and were subjected to +4 °C and 37 °C, for 15, 30 and 45 minutes and sediment was observed for cystine crystals under the microscope. Cystine crystallization had been occurred in the cystinuria of ≥100 mg/dL at pH 5 at 37 ° C and +4 °C, 30min after the addition of acetic acid whereas with the addition of acetone at cystinuria of ≥75mg/dL at pH 5 in both 37°C and at +4°C, 30min after the addition of acetic acid. The number of cystine crystals per High Power Field (HPF) was highest where cystinuria:acetone was 8:1.  The optimum conditions for cystine crystallization is at pH 5, 37 °C and +4 °C, 30min after acidifying with acetic acid at the minimum concentration of 100 mg/dL  of cystinuria. With the addition of acetone, at the ratio of cystinuria:acetone 8:1 with minimum concentration of cystinuria of 75 mg/dL. 

KEYWORDS: Cystine, Crystallization, Acetic acid, Acetone, Temperature, pH