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Abstract: TH-PO373

An Unusual Electrolyte Disturbance in Iron Man Athlete

Session Information

Category: Fluid, Electrolytes, and Acid-Base Disorders

  • 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical


  • Grantham, Connor J., Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Huston, Hunter K., UPMC, Pittsburgh, Pennsylvania, United States

Endurance athletes are at risk for developing numerous electrolyte disorders during competition, famously hyponatremia . The incidence ranges from 0 to 18% in marathoners and triathletes and may be as high as 51% in longer endurance events. Other disturbances with potassium and acid base balance may also be present. The healthcare and performance industries continue to try optimize this balance.

Case Description

A 38 year old male participating in the Ironman World Championship developed exhaustion, tingling in his extremities and swelling. Unable to finish the race, initial medical evaluation revealed a venous pH of 7.64, PCO2 of 57.7, HCO3 level of 62.2. Sodium of 128, potassium of 2.3, chloride less than 65. He received two liters of normal saline and 40mEq of potassium chloride with rapid improvement in his symptoms. Due to prior episodes of hyponatremia and nausea while training, this patient had sought consultation with a company focused on sweat and solute replacement. Testing illustrated a sweat rate of 2.5 L per hour and over 2 g of sodium per liter. He noted improvement in his performance with a concentrated electrolyte mix of sodium and potassium, as well as a dedicated water replacement strategy. However, for this race he used a strictly sodium citrate solution, delivering 25 grams of sodium citrate.


The case represents a unique presentation of citrate toxicity in a high endurance athlete. The patient had been supplementing his electrolytes during this race, using sodium citrate alone with a focus on mitigating sodium loss. He consumed 25 g of sodium citrate over four hours and developed citrate toxicity which contributed to his metabolic alkalosis and hypokalemia. The case demonstrates the importance of maintaining a high index of suspicion for electrolyte abnormalities in athletes. It highlights the role of Nephrology in optimizing fluids and electrolytes for high performance athletes, thereby avoiding hazard and improving performance. Finally, it serves as a reminder to monitor the contents and concentrations of supplements for our patients, itself a burgeoning industry.