The effects of acute hyponatraemia on bone turnover in patients with subarachnoid haemorrhage; a preliminary report.
Clin Endocrinol (Oxf). 2020 Nov 11;: Authors: Garrahy A, Galloway I, Hannon AM, Dineen R, Javadpour M, Tormey WP, Gan KJ, Twomey PJ, Mc Kenna MJ, Kilbane M, Crowley RK, Sherlock M, Thompson CJ
CONTEXT: Animal data and cross-sectional human studies have established that chronic hyponatraemia predisposes to osteoporosis; the effects of acute hyponatraemia on bone turnover have not been determined. Our objective was to test the hypothesis that acute hyponatraemia leads to dynamic effects on bone turnover. DESIGN: A prospective observational pilot study. METHODS: Bone turnover markers [C-terminal crosslinking telopeptide of type 1 collagen (CTX-1), N-propeptide of type 1 collagen (P1NP) and osteocalcin] were measured prospectively over one week in 22 eunatraemic patients with subarachnoid haemorrhage. Patients treated with glucocorticoids were excluded. RESULTS: Eight patients developed acute hyponatraemia, median nadir plasma sodium concentration 131 mmol/L (IQR 128-132), and 14 remained eunatraemic, nadir plasma sodium concentration 136 mmol/L (IQR 133-137). Significant main effects of hyponatraemia were found for P1NP (p=0.02) and P1NP:CTX-1 ratio (p=0.02), both fell in patients with acute hyponatraemia, with significant interaction between hyponatraemia and time from baseline for P1NP (p=0.02). Significant main effects of time from baseline (p<0.001) but not hyponatraemia (p=0.07) were found for osteocalcin. For CTX-1, significant main effects of time from baseline (p=0.001) but not hyponatraemia (p=0.65) were found. There was a positive correlation between change in P1NP:CTX-1 ratio and nadir plasma sodium concentration, r=+0.43, p=0.04. Median serum cortisol (measured on day 1, 3 and 7) was higher in the hyponatraemia group than in those who remained euntraemic, 545 nmol/L (IQR 373-778) versus 444 nmol/L (IQR 379-542) p=0.03. CONCLUSION: These data suggest that acute mild hyponatraemia is associated with a reduction in bone formation activity. PMID: 33176010 [PubMed - as supplied by publisher]