Table 4

Four case reports describing symptomatic EAH while drinking either ad libitum (two cases) or in response to thirst (two cases)

Study (year)Subjects
age (years old) sex (♂♀)
Plasma [Na+] mmol/L
Symptomatic EAH with ad libitum drinking (comments from report)
Baker et al (2005)8565♀
Lab trial
12646 kg♀ drank 2.8 L water and gained 2.4 kg in 2.5 h intermittent cycling trial 30°C
Subjects were not encouraged to drink but told that more fluid was readily available if needed
Hew-Butler, (2012)13428♀
114Subject followed her normal practice of ingesting a GU packet with 200 mL of water every 45 min with Coke and water ad libitum for an estimated fluid consumption rate of ∼550 mL/h
Symptomatic EAH with drinking in response to thirst (comments from report)
Khodaee (2013)10044♂
Mountain biker
11684 kg♂ drank 29 L water and 5.3 g sodium during plus after race (∼14 h total)
History of muscle cramping after 5–6 h cycling. Felt “very thirsty” after the race
Initial labwork in hospital: urine[Na+]=31 mmol/L and BUN=19 mg/dL
Labwork 2 months after hospitalisation: plasma [Na+]=133 mmol/L, BUN=10 mg/dL
Hoffman (2015)7253♂
122Subject began using “regular sodium supplementation” and “very thirsty” at 100 km
2.2% weight gain noted at 126 km and dropped out of race at 145 km (28 h)
Initial labwork in hospital: BUN=22 mg/dL
17 h later in hospital (>10.4 L 0.9% saline), plasma [Na+]=136 mmol/L and BUN=10 mg/dL
Subject received 20 L of IV fluids in hospital and discharged with positive fluid balance of 6.6 L
  • BUN, blood urea nitrogen; EAH, exercise-associated hyponatraemia; IV, intravenous.