Suramin administration is associated with a decrease in serum calcium levels

Suramin has been shown to have an effect on bone resorption in in vitro mod els. It is not clear if a similar effect is seen in patients treated with s uramin. The clinical effect of suramin treatment on total serum calcium was examined in two groups of patients with hormone-refractory prostate cancer . In all, 28 patients in group 1 were examined within 2 weeks before and 2 weeks after suramin treatment and 72 patients in group 2 were examined with in 2 weeks before, during, and after treatment with suramin. In addition. c alcium controls spiked with suramin were run in three different commerciall y available assays for evaluation of the effect of suramin dose on calcium determination. Group 1 patients showed a decrease in serum calcium after tr eatment with suramin. The mean uncorrected serum calcium level was 2.29 +/- 0.025 mmol/l before treatment and 2.09 +/- 0.025 mmol/l after treatment (P < 0.0001, paired Wilcox-on test). The mean serum calcium value corrected f or albumin was 2.33 +/- 0.02 mmol/l before treatment and 2.24 +/- 0.02 mmol /l after treatment (P = 0.0022, paired Wilcoxon test). Group 2 patients als o displayed a decrease in serum calcium after treatment with suramin. The m ean baseline value was 2.23 mmol/l (median 2.26 mmol/l, range 1.2-2.54 mmol /l). The mean level of serum calcium corrected for albumin as determined at the end of treatment was 2.14 mmol/l (median 2.16 mmol/1, range 0.98-2.46 mmol/l). In all, 48 patients for whom pre- and posttreatment values were av ailable for analysis displayed a median calcium decrease of 0.09 mmol/l (P = 0.0005, Wilcoxon signed-rank test for the null hypothesis of no change). For 68 patients in group 2, data on serial serum calcium measurements durin g treatment were available for analysis. A projected median decrease in ser um calcium of 0.06 mmol/l (range -0.43 to 0.72 mmol/l) over an 8-week inter val of suramin therapy was found. Overall, 47 of the 68 slopes were negativ e (P = 0.0022, Wilcoxon signed-rank test). Nine patients were treated with suramin for less than 6 weeks. These patients' calcium levels were signific antly higher than those of 50 patients treated for longer periods (median v alue 2.24 versus 2.16 mmol/l, P = 0.035, Wilcoxon rank-sum test). No correl ation was found between suramin dose and calcium level using the Kodak Ekta chem, Hitachi 914, or Synchron Clinical System CX3 method. In conclusion, s uramin treatment was consistently associated with decreases in serum calciu m in two groups of patients with hormone-refractory cancer. Suramin placed in calcium controls did not affect calcium determination using three commer cially available methods.