Introduction: Hypercalciuria is the most common urinary alteration in patients with kidney stones. Multiple studies reported associations of hypercalciuria with renal lithiasis and elevated bone resorption. Phytate (inositol hexakisphosphate, InsP6) can inhibit kidney stone formation and bone resorption. The main objective of this study is to evaluate the effect of phytate supplements on calciuria in patients with urinary stones and elevated bone resorption. The secondary objective is to analyze the therapeutic effect of phytate based on measurements of serum markers of bone resorption.
Methods: This controlled randomized study enrolled patients according to predefined inclusion and exclusion criteria, and randomized them into two groups. Patients in the phytate group received a 380 mg capsule of calcium-magnesium InsP6 (Broken Laboratories®) every 24 h for 3 months and patients in the control group received no treatment. All included patients were male or female, 18 to 65 years-old, had hypercalciuria (>250 mg/24 h), had a ß-Crosslaps level greater than 0.4 ng/mL, and had bone densitometry results indicative of osteopenia or osteoporosis in the femur and/or spine . The baseline characteristics of patients in both groups were compared using a t-test for independent samples (quantitative data) and a chi-square test or Fisher’s exact test (categorical data). The inter and intragroup comparisons were made using t-test for paired and independent samples and ANCOVA.
Results: At study onset, calciuria was 321±52 mg/24 h in the phytate group and 305±57 mg/24 h in the control group (p>0.05). At 3 months, calciuria was significantly lower in the phytate group than the control group (226±45 mg/24 h vs. 304±58 mg/24 h, p<0.05). At study onset, the mean ß-CrossLaps level was 1.25±0.72 ng/mL in the phytate group and 0.57±0.13 ng/mL in the control group (p < 0.05). However, at 3 months, the ß-CrossLaps level was significantly lower in the phytate group than in the control group (0.57±0.13 ng/mL vs. 0.77±0.42 ng/mL, p<0.05). Thus, calciuria decreased by 29% (±12) in the phytate group and 0.1% (±14) in the control group B (p < 0.05) and the ß-CrossLaps level decreased by 35% (±15) in the phytate group and 0.6% (±14) in the control group (p < 0.05).
Conclusions: Phytate reduced calciuria in patients with hypercalciuria secondary to bone resorption. The ß-CrossLaps assay was effective for evaluating the efficacy of phytate on hypercalciuria during follow-up