14 Sep Hypertension: Lower Chloride Levels Associated with Increased Mortality
MedicalResearch.com: What are the main findings of the study?
Dr. Padmanabhan: In the study “Serum Chloride Is an Independent Predictor of Mortality in Hypertensive Patients” we analysed data on 12,968 patients with hypertension followed up at the Glasgow Blood Pressure Clinic. We found that patients in the lowest quintile of serum Cl− (<100 mmol/L), compared with all other patients, had a 23% higher mortality (all-cause, cardiovascular, and non-cardiovascular). Each 1-mmol/L increase in serum Cl− was associated with a 1.1% to 1.5% lower all-cause mortality, cardiovascular mortality and non-cardiovascular mortality. This was independent of serum concentrations of sodium, bicarbonate or potassium. We did not find any association with longitudinal blood pressure control.
MedicalResearch.com: Were any of the findings unexpected?
Dr. Padmanabhan: The finding that serum chloride <100mol/L was associated with higher mortality was unexpected. The commonly held view, that sodium is the major determinant of BP and adverse outcomes, has resulted in the assumption that any independent effect of chloride is irrelevant. This is because serum chloride was considered an inert bystander in electrochemical equilibrium across cell membranes. Despite serum chloride being a routine measurement of all clinical biochemistry panel, there has only been only one previous paper in 1995 which also showed a low serum chloride was associated with higher mortality.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Padmanabhan: It is too early to say what mechanisms are operative in the inverse association of serum chloride with long-term mortality. Our study should raise awareness among clinicians to consider serum chloride levels as a risk predictor.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Padmanabhan: A lot of research is required to dissect the underpinning mechanism that relates low serum chloride to increased mortality. There is emerging evidence that immune mechanisms have a role in selective Cl− accumulation in the skin which is associated with salt-sensitive hypertension. Other areas of research include chloride transmembrane fluxes, the role of chloride in processes ranging from maintenance of cell volume, apoptosis, insulin secretion, neuronal excitability and vascular inflammation.