Individuals with postural orthostatic tachycardia syndrome (POTS) who have low baseline urinary sodium excretion (<124 mmol/24 hours) were more likely to benefit from sodium supplementation (J Pediatr 2012; 161: 281-4). In this group, “as much as 90% of patients” will improve with salt supplements.
This study from China examined the effects of sodium supplementation in 30 children (20 females, 10 males) as well as in 10 control patients to identify factors which related to therapeutic response. Criteria for POTS included orthostatic intolerance (without orthostatic hypotension –blood pressure drop >20/10 mm Hg) accompanied by a heart rate increase of >30/min within the first 10 minutes of standing.
Despite normal serum sodium, POTS cohort had baseline 24-hr sodium excretion of 117 ± 59 compared with control of 194 ± 91. POTS sodium-responders were similar in all aspects at baseline except for lower sodium excretion: 85 ± 35 compared to 150 ± 51 for POTS sodium-nonresponders.
The discussion reviews the theoretical reasons for POTS response to sodium (e.g.. ‘relative hypovolemia’) and points out that there are several subtypes, including ‘hypovolemic,’ hyper-adrenergic,’ and ‘autoimmune.’ Salt supplementation which has been shown to be effective only in the pediatric population targets the hypovolemic subset.
- Small sample size
- Lower sodium excreters had more symptoms at baseline & therefore may have led to bias as well
- -J Pediatr 2011; 158: 20 (pg 4 editorial). n=53. GI pain in 75%, nausea/vomiting in large fraction, sleeping problems in 98%, headache, syncope, urinary symptoms. May have poor stomach emptying due to autonomic dysfunction
- -J Pediatr Gastroenterol Nutr. 2010 Sep;51(3):314-8. Gisela Chelimsky “Gastric Electrical Activity Becomes Abnormal in the Upright Position in Patients With Postural Tachycardia Syndrome”
- -J Pediatr 2011; 158: 499. Orthostatic hypotension can be treated physically: gripping hands for 15 secs before rising, lower body muscle contraction (eg pumping calf muscles/tensing legs), squatting…