Effect of potassium levels on death rate in patients with high blood pressure

This paper studied the impact of potassium levels on mortality in patients with high blood pressure. The authors found that potassium levels less than 4.1 mmol/L and larger than 4.7 mmol/L increased the risk of mortality. 

Treatments for high blood pressure, such as diuretics, beta-blockers, ACE inhibitors and angiotensin receptor blockers, can affect potassium levels. Normal potassium levels in the body range between 3.5 mmol/l and 5 mmol/l. Abnormal levels of potassium have been associated with an increased risk of mortality. However, the relationship between potassium levels and mortality is not clear.

The current study examined the relationship between potassium and mortality in 44,799 patients. These patients were receiving at least 2 high blood pressure drugs. Potassium levels were analyzed for each patient.

Women were more likely to have low potassium levels (less than 3.5mmol/L). Men more often had high potassium levels (greater than 5 mmol/L). The average potassium level was 4.20 mmol/L. 1.9% of patients died during the 90-day follow-up.

Patients with potassium levels between 4.1 and 4.4 mmol/L had the lowest risk of death. Patients with potassium levels less than 3.5 mmol/l were 2.8 times more at risk of death. Patients with potassium levels more than 5 mmol/l were 1.7 times more at risk of death. Patients with potassium levels of 3.5– 3.7 mmol/L were 1.70 times more at risk of death. Patients with potassium levels between 4.8–5.0 mmol/L were 1.48 times more at risk of death.

After considering various other factors, death rate remained significantly increased for all potassium ranges outside the interval of 3.8–4.7 mmol/L. Patients with other illnesses such as chronic obstructive pulmonary disease, atrial fibrillation, heart failure, and stroke also had an increased mortality risk.

ACE inhibitors or angiotensin receptor blockers in combination with thiazide diuretics did not increase mortality risk. However, a combination of beta-blockers with thiazide diuretics and potassium supplements was associated with a 1.46 increased risk of death. 

The authors concluded that potassium levels outside the interval of 4.1–4.7 mmol/L were associated with increased risk of death in patients with high blood pressure. 

Talk with your doctor about your potassium levels.