title: Hypernatremia and intravenous fluid resuscitation in collapsed ultramarathon runners.
abstract: To determine if a return to normonatremia is required for symptomatology to resolve in collapsed hypernatremic runners and if intravenous (IV) administration of an isotonic solution would adversely affect serum sodium concentration ([Na+]) in collapsed normonatremic runners.
  
  
  
  Observational study.
  
  
  
  2006 Comrades Marathon.
  
  
  
  103 collapsed runners.
  
  
  
  Final serum [Na] upon discharge.
  
  
  
  58% of all collapsed runners were hypernatremic. Hypernatremic runners reported significantly more vomiting than normonatremic runners (79 versus 34%; P < 0.001). A significant decrease in serum [Na] in hypernatremic collapsed runners occurred after the IV administration of either 1 L of 0.45% normal saline (150.5 +/- 3.5 versus 148.0 +/- 4.6; P < 0.05) or Ringers lactate solution (147.7 +/- 2.2 versus 146.2 +/- 2.1; P < 0.05). One liter of IV fluid administration caused an increase in plasma volume that was not significantly different between (1) hypernatremic runners receiving a hypotonic solution (13.5 +/- 12.7%) and (2) normonatremic runners receiving an isotonic solution (15.6 +/- 11.3%). The final serum [Na+] of hypernatremic runners was above the range for normonatremia upon discharge (>145 mmol/L).
  
  
  
  A return to normonatremia was not required for hypernatremic runners to "recover" and be discharged from the medical tent. Vomiting either aggravated and/or facilitated the development of hypernatremia. IV administration of 1 L of either (1) a hypotonic solution to hypernatremic runners or (2) an isotonic solution to both normonatremic and hypernatremic runners did not produce any adverse biochemical or cardiovascular changes and can therefore be considered a safe and effective treatment for collapsed runners if used in this context.
authors.affiliation: Department of Human Biology, University of Cape Town, Cape Town, South Africa. tamara.hew@chw.edu
authors.forename: Tamara
authors.initials: T
authors.lastname: Hew-Butler
authors.forename: Jeremy
authors.initials: J
authors.lastname: Boulter
authors.forename: John
authors.initials: J
authors.lastname: Godlonton
authors.forename: Ross
authors.initials: R
authors.lastname: Tucker
authors.forename: Timothy
authors.initials: T
authors.lastname: Noakes
mesh_terms: D005260:Female; D006801:Humans; D006955:Hypernatremia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D007262:Infusions, Intravenous; D008297:Male; D019370:Observation; D005082:Physical Exertion / Q000502:physiology*; D012420:Running; D012964:Sodium / Q000032:analysis / Q000097:blood; D013019:South Africa
chemical_list: D012964:Sodium