Association of abnormal serum electrolyte levels with hypertension in a population with high salt intake.

objectiveThe present epidemiological study aimed to evaluate the association of serum electrolyte levels with hypertension in a population with a high-salt diet.

designSecondary analysis of epidemiology data from the Northeast China Rural Cardiovascular Health Study conducted in 2012-2013. Blood pressure and hypertension status were analysed for association with serum sodium, potassium, chloride, total calcium, phosphate and magnesium levels using regression models.

settingHigh-salt diet, rural China.ParticipantsAdult residents in Liaoning, China.

resultsIn total 10 555 participants were included, of whom 3287 had incident hypertension (IH) and 1655 had previously diagnosed hypertension (PDH). Fifty-six per cent of participants had electrolyte disturbance. Sixty-two per cent of hypercalcaemic participants had hypertension, followed by hypokalaemia (56 %) and hypernatraemia (54 %). Only hypercalcaemia showed significant associations with both IH (OR=1·70) and PDH (OR=2·25). Highest serum calcium quartile had higher odds of IH (OR=1·58) and PDH (OR=1·64) than the lowest quartile. Serum sodium had no significant correlation with hypertension. Serum potassium had a U-shaped trend with PDH. Highest chloride quartile had lower odds of PDH than the lowest chloride quartile (OR=0·65). Highest phosphate quartile was only associated with lower odds of IH (OR=0·75), and the higher magnesium group had significantly lower odds of IH (OR=0·86) and PDH (OR=0·77).

conclusionsWe have shown the association of serum calcium, magnesium and chloride levels with IH and/or PDH. In the clinical setting, patients with IH may have concurrent electrolyte disturbances, such as hypercalcaemia, that may indicate other underlying aetiologies.