Hyponatremia in marathon runners due to inappropriate arginine vasopressin secretion.

Abstract

PURPOSE:

Exercise-associated hyponatremia (EAH), as defined by a blood sodium concentration [Na+] less than 135 mmol/L, may lead to hypotonic encephalopathy with fatal cerebral edema. Understanding the pathogenetic role of antidiuresis may lead to improved strategies for prevention and treatment.

METHODS:

Normonatremic marathon runners were tested pre- and post-race for creatine kinase, interleukin-6, cortisol, prolactin, and arginine vasopressin. Similar testing also was carried out in runners with encephalopathy caused by EAH, including 2 cases with fatal cerebral edema.

RESULTS:

Normonatremic runners (n = 33; 2001) with a mean 3% decrease in body weight showed a 40-fold increase in interleukin-6 (66.6 +/- 11.9 pg/mL from 1.6 +/- 0.5 pg/mL, P = .001), which was significantly correlated with increases in creatine kinase (r = 0.88, P = <.0001), cortisol (r = 0.70, P = .0003), and prolactin (r = 0.67, P <.007), but not arginine vasopressin (r = 0.44, P = .07). Collapsed runners with EAH (n = 22; 2004) showed a mean blood urea nitrogen less than 15 mg/dL with measurable plasma levels of arginine vasopressin (>0.5 pg/mL) in 43% of cases. Two marathon runners with fatal cerebral edema additionally showed less than maximally dilute urines (>100 mmol/kg/H2O) and urine [Na+] greater than 25 mEq/L.

CONCLUSIONS:

Cases of EAH fulfill the essential diagnostic criteria for the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Runners with hypotonic encephalopathy at subsequent races were treated with intravenous hypertonic (3%) saline on the basis of this paradigm, which resulted in rapid clinical improvement without adverse effects. Release of muscle-derived interleukin-6 may play a role in the nonosmotic secretion of arginine vasopressin, thereby linking rhabdomyolysis to the pathogenesis of EAH.

• Authors: Arthur J Siegel, Joseph G Verbalis, Stephen Clement, Jack H Mendelson, Nancy K Mello, Marvin Adner, Terry Shirey, Julie Glowacki, Elizabeth Lee-Lewandrowski, Kent B Lewandrowski
• Journal: The American journal of medicine (Am J Med) Vol. 120 Issue 5 Pg. 461.e11-7 (May 2007) ISSN: 1555-7162 [Electronic] United States
• PMID: 17466660 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Interleukin-6
• Arginine Vasopressin
• Prolactin
• Creatine Kinase
• Hydrocortisone

Topics

• Adult
• Arginine Vasopressin (blood, metabolism)
• Blood Urea Nitrogen
• Brain Edema (etiology)
• Creatine Kinase (blood)
• Female
• Humans
• Hydrocortisone (blood)
• Hyponatremia (etiology)
• Inappropriate ADH Syndrome (diagnosis, etiology)
• Interleukin-6 (blood)
• Male
• Middle Aged
• Physical Endurance (physiology)
• Prolactin (blood)
• Radioimmunoassay
• Running (physiology)