Table 4.

Serum Thyroid Hormone Levels in Peripheral Blood Samples

Group	Pre-op	Pre-CPB	Post-CPB	Post-op 6 h	Post-op 24 h	p
Valve Replacement
T3 (ng/mL)	1.13 ± 0.30	0.92 ± 0.26*	0.73 ± 0.15*	0.79 ± 0.20*	0.71 ± 0.14*	<0.001
rT3 (ng/mL)	0.26 ± 0.08	0.21 ± 0.07	0.19 ± 0.05	0.38 ± 0.10*	0.63 ± 0.21*	<0.001
T4 (ng/mL)	95.5 ± 14.5	90.2 ± 21.3	76.2 ± 10.8*	84.4 ± 17.3	82.2 ± 19.1	<0.001
FT4 (ng/mL × 102)	1.35 ± 0.23	2.12 ± 0.52	1.97 ± 0.42	1.31 ± 0.24	1.34 ± 0.26	N.S.
TSH (μU/mL)	1.83 ± 1.39	1.29 ± 0.97	2.04 ± 1.82	0.85 ± 1.09	0.62 ± 0.61*	<0.001
CABG Off-pump
T3 (ng/mL)	1.08 ± 0.24	0.84 ± 0.28	0.74 ± 0.28*	0.60 ± 0.23*	0.61 ± 0.20*	<0.001
rT3 (ng/mL)	0.25 ± 0.13**	0.23 ± 0.10**	0.22 ± 0.14**	0.41 ± 0.33**	0.68 ± 0.23	<0.001
T4 (ng/mL)	76.8 ± 33.6	98.8 ± 26.0	80.0 ± 31.2	71.3 ± 26.0	75.7 ± 25.9	0.118
FT4 (ng/mL × 102)	1.29 ± 0.29	1.98 ± 0.39	1.72 ± 0.33	1.21 ± 0.22	1.32 ± 0.35	N.S.
TSH (μU/mL)	2.06 ± 1.61	1.80 ± 1.32	2.23 ± 3.49	0.73 ± 0.63	0.51 ± 0.27	<0.001
CABG CPB
T3 (ng/mL)	1.08 ± 0.23	0.71 ± 0.26*	0.66 ± 0.22*	0.75 ± 0.20*	0.71 ± 0.15*	<0.001
rT3 (ng/mL)	0.24 ± 0.05**	0.18 ± 0.07**	0.24 ± 0.35**	0.35 ± 0.06**	0.65 ± 0.33	<0.001
T4 (ng/mL)	87.4 ± 19.2	79.1 ± 20.1*	64.1 ± 13.3	77.2 ± 16.8	77.0 ± 19.1	<0.001
FT4 (ng/mL × 102)	1.27 ± 0.17	1.80 ± 0.33	1.65 ± 0.29	1.27 ± 0.17	1.27 ± 0.23	N.S.
TSH (μU/mL)	1.69 ± 0.83**	1.41 ± 1.51**	1.26 ± 0.63	0.54 ± 0.23*,***	0.55 ± 0.45	<0.001

Values are the mean ± SD.

Note that heparin, given at the time of CPB reacts with T4-binding proteins and leads to an overestimation of FT4 values.

Reference ranges for peripheral blood are: T3 (0.7–1.8 ng/mL); rT3 (0.10–0.24 ng/mL); T4 (45–120 ng/mL); FT4 (0.6–1.3 ng/mL × 10²); TSH (0.45–4.5 μU/mL).

Statistical analysis was by ANOVA; post-test analysis was by Bonferroni's multiple comparison test.

^*p < 0.05 vs. pre-op; ^**p < 0.05 vs. post-op 24 h; ^***p < 0.05 vs. post-CPB.

N.S., not significant.