The effect of sodium thiosulfate administration on nephrocalcinosis in a rat model

Sodium thiosulfate (STS) is a U.S. Food and Drug Administration (FDA)-approved chelating agent that is used for the treatment of cyanide poisoning and prophylaxis against cisplatin nephropathy. Recently, STS has also been used in the treatment of calciphylaxis, which is a disease characterized by calcification in the soft tissues with vascular calcification and thrombosis causing nonhealing ulcers. We proposed a rat model to evaluate whether STS has any possible beneficial effect on calcium nephrolithiasis or nephrocalcinosis.

Twenty-one male Sprague-Dawley rats were used in the study. All animals received standard rat chow throughout the experiment. The animals were started on special drinking water containing 0.4% ethylene glycol plus 1.0% ammonium chloride for 7 days to induce crystalluria and nephrocalcinosis. The animals were then randomized to two groups. Group 1 served as a control and received daily intraperitoneal injections of normal saline. Group 2 received daily intraperitoneal injections of STS solution. Special drinking water containing 0.8% ethylene glycol was continued during the treatment period.

Group 2 gained significantly less weight than group 1 (18.0% v 8.5%, p < 0.05). The amount of crystalluria in group 2 was much less than that in group 1, but did not reach statistical significance (0.7 v 4.2, p = 0.09). Degree of calcification noted in the kidneys was not statistically different between the two groups.

The current study did not reveal any significant benefit of STS administration on calcium stone disease. However, many more studies are necessary before the possibility of a beneficial effect is completely disproved.