Effects of Short Term Alendronate Administration on Bone Mineral Density in Patients with Chronic Kidney Disease

Abstract

Background: Osteoporosis is highly prevalent in CKD patients and is characterized by low bone mass leading to decreased bone strength. It is associated with an increased risk of fracture, thus increasing morbidity and mortality. Bisphosphonate administration decreases fracture risk in postmenopausal females with osteoporosis. There are limited studies showing effects of short term alendronate administration on BMD in predialysis osteoporotic patients with CKD.

Methods: This study was conducted on fifty adult patients with chronic kidney disease. Patients were divided into two groups. Group A consisted of seventeen patients with CKD stage 3 (eGFR 45-30 ml/min/1.73m²) and Group B comprised thirty three patients with CKD stage 4 (eGFR 30-15 ml/min/1.73m²). The study included male patients between age 18-75 years and premenopausal non pregnant females older than 18 years of age. All the patients were osteoporotic having T score < −2.5 on DEXA scan. The patients were administered 70 mg alendronate tablet once a week for 6 weeks. Renal parameters, parathyroid hormone, calcium, phosphorous and alkaline phosphatase levels were assayed at baseline for 6 months. Serum (iPTH) level (pg/ml) was measured by chemiluminescent immune assay (CLIA) method and serum 25 Hydroxy Vitamin D level (ng/ml) was measured by enzyme linked immunosorbent assay (ELISA) method. Bone Mineral Density (BMD) was measured at baseline for 6 months, by dual energy x-ray absorptiometry at lumbar spine and neck of femur and lowest values were included. The results were obtained for T score, Z score and bone mineral density (g/cm²).

Results: The BMD, T score and Z score increased in both groups after 6 months with a statistically significant difference in the treatment group. In Group A, T score, Z score and BMD (g/cm²) increased from −2.60±0.086, −2.13±0.28, and 0.80±0.008 at baseline to −2.57±0.097, −2.11±0.26 and 0.81±0.008 after six months. In Group B, the T score, Z score and BMD (g/cm²) increased from −3.17±0.24, −2.82±0.33 and 0.738±0.03 to −3.16±0.25, −2.66±0.95 and 0.743±0.03 after six months with a statistically significant difference. eGFR decreased in both groups but the difference was statistically non-significant (P>0.05). The serum iPTH levels increased after 6 months in both groups with a statistically insignificant difference. There was an increase in serum calcium and decrease in serum phosphate levels after six months, however the difference was statistically insignificant (p>0.05). The SAP values decreased in both groups after six months with a statistically insignificant difference. The main side-effect in the alendronate group was the occurrence of gastroesophageal reflux symptoms in two subjects.

Conclusion: Low-dose alendronate, administered for a limited duration, appears to be well tolerated in CKD patients. The BMD increased in both groups suggesting a bone-preserving effect of alendronate.