Endocrine Abstracts

Objectives: International and national guidelines on the treatment of chronic non-hypovolaemic hypotonic hyponatraemia differ widely. Using methods embodied in the Cochrane Handbook, a systematic review and meta-analysis was conducted to investigate the efficacy and safety of interventions for this condition.

Methods: Following registration of the review protocol with PROSPERO (CRD42015016670), systematic literature searches were conducted to identify randomised or quasi-randomised controlled trials comparing any degree of fluid restriction or any drug treatment with the aim of increasing serum sodium concentration in patients with chronic non-hypovolaemic hypotonic hyponatraemia. Where possible and appropriate, outcome data were combined in a meta-analysis.

Results: 45 716 records (i.e. bibliographic references) were identified from the searches and 18 trials (assessing conivaptan, lixivaptan, tolvaptan and satavaptan) met the eligibility criteria. No RCT evidence was identified for effectiveness of treatments other than for the ‘vaptans’ (listed above) for hyponatraemia. Results suggest that all four vaptans significantly improve serum sodium concentration. Lixivaptan, tolvaptan and satavaptan were associated with greater rates of response versus placebo. There was no evidence of a difference between any of the vaptans compared with placebo for mortality, discontinuation and rates of hypernatraemia.

Conclusions: Vaptans demonstrated superiority over placebo for outcomes relating to serum sodium correction. Few studies measured health-related quality of life (QoL) using a range of different instruments and showed no evidence that vaptans negatively impact QoL. For all vaptans, cases of overcorrection were rare. With the exception of vaptans, no RCT evidence was identified in relation to the alternative strategies commonly employed including urea, mannitol, loop diuretics, corticosteroids, demeclocycline, lithium and phenytoin.