Changes in Bone Mineral Density Following Conventional Oral Phosphonate Treatment of Hypophosphatemic Osteomalacia: A Non-Randomized Controlled Study

PURPOSE: There are limited clinical studies aimed at solving the problem of the efficiency of conventional treatment with oral phosphate and calcitriol in adults with hypophosphatemic osteomalacia (HO). In addition, there still had no good non-hazardous markers to evaluate the severity of bone loss of osteomalacia before and after treatment. Therefore, the purpose of this study was to assess the efficacy of conventional treatment with a self-blended phosphate supplementation and calcitriol on patients with HO and whether bone mineral density (BMD) can be helpful for monitoring the efficacy. PATIENTS AND METHODS: A total of 21 HO patients and 105 healthy controls were enrolled. All patients were tested for serum biomarkers and BMD of the lumbar spine (L1–L4), femoral neck, and total left hip. After three years of treatment, 11 of 21 HO patients were recalled for BMD measurement. According to the administration of drugs, HO patients with calcium and calcitriol were divided into three phosphate treatment groups: patients in group A (n = 3) received continuous phosphate supplementation, patients in group B (n = 5) received intermittent phosphate supplementation and patients in group C (n = 3) received no phosphate supplementation. RESULTS: The diagnoses of 21 HO patients were 5 cases of hereditary hypophosphatemic rickets, 4 cases of Fanconi syndrome with the features of renal tubular acidosis and vitamin D deficiency, and 12 cases of hereditary vitamin D abnormality. The average initial serum phosphorus level of the patient group was approximately 50% lower than that of the control group. Lower BMD was significantly observed in the HO group than the control group at the lumbar spine and total hip. Continuous treatment with the phosphate supplement could increase BMD in the lumbar spine and total hip by 33.4–52.3% and in the femoral neck increased by 43.2–79.3% compared with baseline, and the effect appears to be continued once treatment is discontinued. CONCLUSION: These findings suggest that conventional therapy can improve bone mineral defects in patients with HO, especially in the femoral neck. Detection of BMD in HO patients is a good tool to assess the extent of bone defects and the therapeutic effect. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR-OOC-16010095. Registered 7 December 2016. Retrospectively registered.