Urinary Sodium and Potassium, and Risk of Ischemic and Hemorrhagic Stroke (INTERSTROKE): A Case–Control Study

Low sodium intake (<2 g/day) and high potassium intake (>3.5 g/day) have been proposed as public health interventions to decrease stroke risk. Still, there is uncertainty about the positive outcomes and feasibility of this combined recommendation on the prevention of stroke. Conor Judge and a colleague published a study in the American Journal of Hypertension under the title “Urinary Sodium and Potassium, and Risk of Ischemic and Hemorrhagic Stroke (INTERSTROKE): A Case-Control Study”. The summary of the findings is given below:

Objective:

To study the associations of estimated sodium and potassium excretion with stroke and its subtypes.

Method:

Random urine samples were collected from 9,275 individuals of acute first stroke and 9,726 matched controls from 27 countries. The 24-hour sodium and potassium excretion, a surrogate for intake, was estimated using the Tanaka formula. The associations of estimated 24-hour urinary sodium and potassium excretion with stroke and its subtypes were determined using multivariable conditional logistic regression.

Findings:

The study reports an estimated sodium excretion of < 2.8 g/day and >4.26 g/day are both associated with an increased risk of stroke. Additionally, potassium excretion of >1.34 g/day was associated with a reduced risk of stroke. The J-shaped association has been reported between sodium intake and stroke risk, with the lowest risk at moderate sodium intake. The high sodium intake was strongly associated with ischemic or intracerebral hemorrhage (ICH) as compared with ischemic stroke and within ischemic stroke subtypes. This association was significant for small vessel and large vessel ischemic stroke, but not significant for cardioembolic stroke. On the other hand, there was an inverse and linear association between estimated potassium excretion and risk of ischemic stroke, but not significant for ICH. With high potassium intake, the magnitude of association for both low and high sodium excretion was decreased.

Reports suggest the lowest risk of stroke with the highest potassium intake and moderate sodium intake.

Limitation:

The authors highlight certain limitations such as sampling bias and measurement bias. Secondly, there is a chance of potential acute effects of stroke on excretion of sodium intake. Lastly, increasing time from admission to urinary sample measurement may decrease the correlation of general dietary intake with the urinary estimate.

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