Table 1. Comparison of thyroid hormone test results according to the method of detection.

Test item	SI Unit	Siemens (One-step)	RI	Abbott (Two-step)	RI	RIA	RI	Direct dialysis	RI
Free T4	pmol/L	54.70	11.46–23.17	13.00	9.01–19.05	16.73	8.24–22.14	11.58	10.30–34.75
Total T4	nmol/L	140.28	41.18–162.16	Not tested	Not applicable	Not tested	Not applicable	Not applicable	Not applicable
TSH	mIU/L	6.23	0.55–4.78	5.97	0.35–4.94	7.98	0.3–6.50	Not applicable	Not applicable
Total T3	nmol/L	1.50	0.92–2.79	1.55	0.89–2.45	1.77	1.17–2.93	Not applicable	Not applicable

Abbreviations: RI, reference interval; RIA, radioimmunoassay; T3, triiodothyronine; T4, thyroxine; TSH, thyroid stimulating hormone.