A 58 year-old man presented with backache and was found to have T10-T12 vertebral fractures on spinal-MRI. He was diagnosed with osteoporosis on a DEXA-scan (lumbar-spine T-score-2.6) and was treated with Alendronate and Cholecalciferol at a neighboring hospital. He was referred to the endocrine bone-clinic for a second opinion regarding his osteoporosis. He had a history of multiple small bone fractures and Brucellosis that required a 2-month bed-rest. His family history included early-onset osteoporosis in his father and brother. He didnt consume excessive alcohol nor smoke and had no hypogonadal symptoms/signs. Investigations excluded secondary causes of osteoporosis; he had a mildly elevated PTH (8 pmol/l) [ref.1.6-7.2] and low-normal adjusted-calcium (2.34 mmol/l) [ref. 2.2-2.6]. Endocrinopathy and haematological screens were unremarkable; (Hb 154 g/l [ref. 130-168], phosphate 1.01 mmol/l [ref. 0.80-1.50], ALP 65 U/l [ref. 30-130], normal renal/thyroid function, 25(OH)Vitamin-D 50 nmol/l [ref. 50-150], LH 4.3 U/l [ref. 2-12], testosterone 16 nmol/l [ref. 10-30]. He had an elevated 24-h urinary-calcium (10.1 mmol/24h [ref. 2.5-7.5]), which in the absence of other hypercalciuria causes, suggested Idiopathic Hypercalciuria as the main cause of osteoporosis. Other risk factors included the prolonged bed-rest during Brucellosis and family history of osteoporosis. A renal-ultrasound did not show nephrolithiasis or nephrocalcinosis. The patient was started on Indapamide MR (1.5mg once-daily) and was advised to maintain a low-salt diet and high fluid intake (≥2L/day). A repeat DEXA scan 3-years after Alendronate and 1-year of Indapamide treatment showed improvement in the bone mineral density (osteopenia in the lumbar spine;T score -1.9). This case demonstrates the importance of investigating for secondary causes of osteoporosis, especially in young men. It highlights the relevance of family history, as Idiopathic Hypercalciuria is associated with a higher polygenic risk of osteoporosis in first-degree relatives.
13 Nov 2023 - 15 Nov 2023