Effect of High Dietary Sodium Intake in Patients With Postural Tachycardia Syndrome, 2021, Garland et al

High Sodium Intake in Patients With Postural Orthostatic Tachycardia Syndrome: A Practice “Worth Its Salt”

Editorial Comment
Blair P. Grubb
Journal of the American College of Cardiology, 2021 May, 77 (17) 2185–2186

https://www.jacc.org/doi/10.1016/j.jacc.2021.03.229

Short extract:
"Studies have demonstrated that POTS patients have a decreased volume of plasma and high serum norepinephrine levels that occur with standing. In addition, rapid volume expansion with intravenous saline solutions have been shown to reduce upright tachycardia and improve symptoms in patients suffering from POTS. It would be reasonable to assume, therefore, that increasing oral sodium intake would have a salutary effect on the physiologic derangements that occur in POTS. A quarter-century ago, a series of studies demonstrated that salt supplementation can increase plasma volume and orthostatic tolerance in patients with unexplained syncope as well as increasing baroreceptor sensitivity (3,4). However, up until now, no one has prospectively evaluated whether increased dietary sodium intake would have similar effects in POTS.

In this issue of the Journal, the study by Garland et al. (5) provides a welcome answer to the question. In a well designed study, they compared the effects of a low-sodium (10 mEq sodium/day) versus a high-sodium diet (300 mEq sodium/day) on orthostatic heart rate and low blood pressure increases as well as orthostatic changes in serum norepinephrine, epinephrine, aldosterone, plasma renin activity (PRA), and plasma volume in both POTS patients and matched control subjects. They convincingly showed that compared with those on a low-sodium diet, subjects on a high-sodium diet demonstrated a smaller increase in heart rate and lower norepinephrine level, PRA, and aldosterone level while upright. Interestingly, blood volume was lower in POTS patients then that of healthy control subjects, even with a high-sodium diet. This finding matches well with previous data that many POTS patients are clinically hypovolemic. Interestingly, while orthostatic symptoms improved while on the high-sodium diet, the decline did not reach statistical significance. However, this may have been due to difficulties in the measurement tool used."

Note: This editorial is discussing this study: https://www.sciencedirect.com/science/article/abs/pii/S0735109721006306