Table 4.

Group 1 (Trekkers) - Subjects arriving at each laboratory and reasons for absence from laboratory

	Kathmandu (1300 m)	Namche (3500 m)	Pheriche (4250 m)	Everest Base Camp (5300 m)
No of Trekkers Arriving at Laboratory	198	197	195	190
Reason for Absence from Laboratory - gender, age, expedition day	nil absent	Respiratory Tract infection (1) M, age 73, Day 1	Abcess (1) M, age 49, Day 3 AMS (1) F, age 55, Day 3	AMS (1) F, Age 39, Day 10 Angina (1) F, age 60, Day 7 Respiratory Tract Infection (1) M, age 68, Day 7 Diarrhoea and Vomiting (1) F, age 59, Day 10 Recurrent Cluster Headache (1) M, age 62, Day 8

Notes: AMS = Acute Mountain Sickness; M = male; F = Female