Endocrine Abstracts

Background: Low serum sodium levels were associated both in experimental studies and in clinical practice with increased prevalence of osteoporosis, due to decreased bone mineralization and increased osteoclastic activity. On the other hand, hyponatremia – independent of osteoporosis – is associated with fracture occurrence.

Objectives: To assess the relationship between serum sodium levels and osteoporotic fractures.

Patients and methods: 160 patients (7M/153F), aged 62.2±11 years were retrospectively assessed. DXA measurement was performed in 133 patients. In all the other 27 patients, DXA was not considered mandatory due to presence of osteoporotic fractures (femoral neck in 18 patients and distal radius in nine patients). Serum natremia was measured in all patients.

Results: 41 out of 160 patients (25.6%) showed various types of osteoporotic fractures (vertebral fractures, femoral neck or distal radius fractures). Patients with osteoporotic fractures were significantly older (71.6±9.5 vs 58.9±11 years, P<0.001, t-test) and had significantly lower serum sodium levels (139.2±3.1 vs 141.1±5.32 mmol/l, P=0.01, t-test) compared to patients without osteoporotic fractures. Prevalence of hyponatremia (serum Na <135 mmol/l) was higher in patients with osteoporotic fractures (four out of 41 – 9.7%) as compared with patients without fractures (six out of 119 – 5.04%), but without reaching statistical significance (P=0.28,=χ² test).

In patients with DXA assessment, n=27 showed normal bone mineral density (group A), n=55 showed osteopenia (group B) and n=51 patients showed osteoporosis scores (group C). Prevalence of hyponatremia tends to be lower in groups A and B (1/27–3.7 and 2/55–3.6%) than in group C (4/51–7.8%).

Conclusion: We suggest measurement of sodium serum levels in elderly people at risk of osteoporotic fractures.