Table 5.

fT4 concentrations (pmol/L) at different altitude levels in the whole group of subjects and differences relative to PR.

	Mean ± s.d.	N	Differences relative to Pr
			Coefficient ± s.e.	P value	95% CI
PR	12.7 ± 1.5	39
BC1	15.2 ± 2.2	38	2.5 ± 0.3	<0.001	2.0; 3.0
C2	15.4 ± 2.3	31	2.7 ± 0.3	<0.001	2.2; 3.3
C3	16.1 ± 2.1	13	3.9 ± 0.4	<0.001	3.1; 4.6
BC2	14.1 ± .2.1	28	1.5 ± 0.3	<0.001	1.0; 2.1
PO	12.3 ± 1.5	38	−0.4 ± 0.3	0.1.76	−0.9; 1.2

Variation of fT4 was not sex, SaO₂ or paO₂ dependent.

Altitudes: PR, Pre expedition = 550 m; BC1, Base Camp 1 = 4.844 m; C2, Camp2 = 6022 m; BC2, Base Camp 2 (after acclimatization) = 4.844 m; C3, Camp3 = 7050 m; PO, Post expedition = 550 m.