Case History: A 64 year old lady with osteoporosis was referred for parental antiresorptive therapy due to a history of oral bisphosphonate intolerance. She was screened for osteoporosis at age 53 after her mother suffered a hip fracture, DEXA showing an L2-L4 T score of −2.5 and mean femur −2.2. She was given a trial of alendronate, but stopped due to indigestion. On Calcium and Vitamin D supplementation, the DEXA after 4 years showed improvement of both the spine and femur densities, but after another 5 years, there was a loss in BMD of 0.9% in the spine and 8.2% in the hip. There was no history of previous fragility fractures, she had never taken steroids and did not have rheumatoid arthritis. She was a current smoker. Her menarche was at age 10 and menopause at age 50. Her mother also had a history of kidney stones. Clinical examination did not suggest the presence of any endocrinopathy or other secondary cause of osteoporosis.
Investigations: Full blood count, renal, and liver profiles were within normal limits. Bone profile showed, CoCa 2.41 mmol/l, Phosphate 0.89 mmol/l, PTH 4.9 pmol/l and 25(OH)VitD 116 nmol/l. TFTs and Protein electrophoresis were unremarkable. 24hr urine calcium showed marked hypercalciuria of 9.25 mmol in total (NR 2.57.5).
Treatment: FRAX score suggested a 10 year probability of major osteoporotic fracture of 22% and hip fracture of 5.1%; treatment was recommended. The patient was not keen to start parental bisphosphonates, but agreed to take indapamide MR 1.5 mg od. Two years later, bone mineral density in 2018 showed a 5.7% and 7.9% improvement in the density of the spine and mean femora respectively. Based on WHO classification, she is currently in the osteopaenic range.
Conclusions and points for discussion: This case illustrates the importance of looking for secondary causes of osteoporosis, as targeting the underlying cause could be the best treatment option. Studies have shown that administration of a thiazide, as indapamide, with bisphosphonate therapy is associated with a greater reduction in hypercalciuria and improvement in bone density than with bisphosphonate therapy alone. Recent secondary analyses highlight the lower fracture risk in patients using thiazide diuretics compared with other antihypertensive drugs. Studies in individuals with hypercalciuria to examine the efficacy of thiazides, or thiazide-like diuretics, alone or in combination with bisphosphonates in improving bone density and reducing fracture risk are indicated.