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 (♂♀) activity | Plasma [Na+] mmol/L (initial) | Symptomatic EAH with ad libitum drinking (comments from report) |
|---|---|---|---|
| Baker et al (2005)85 | 65♀ Lab trial | 126 | 46 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)134 | 28♀ cyclist | 114 | Subject 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)100 | 44♂ Mountain biker | 116 | 84 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)72 | 53♂ Ultrarunner | 122 | Subject 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.