Table 3.

Reference interval of FT3 (pmol/L)

	First trimester	Second trimester	Third trimester	Post-partum
Sample size	139	139	139	55
Mean + 2SD
Lower limit	3.88	3.61	3.59	4.18
90% CI	3.73–4.02	3.53–3.71	3.51–3.67	4.04–4.33
Upper limit	6.05	5.38	5.37	6.33
90% CI	5.92–6.17	5.25–5.50	5.23–5.52	6.04–6.66
Percentile non parametric method
Lower limit	3.74	3.53	3.49	3.97
90% CI	3.46–4.09	3.32–3.72	3.36–3.75	–*
Upper limit	6.06	5.54	5.48	6.71
90% CI	5.84–6.64	5.13–5.74	5.22–5.71	–*
Robust method
Lower limit	3.87	3.61	3.58	4.16
90% CI	3.71–4.0	3.51–3.70	3.50–3.66	4.00–4.34
Upper limit	6.06	5.39	5.39	6.41
90% CI	5.94–6.20	5.26–5.52	5.23–5.54	6.06–6.76

–*Not calculated, as recommended by CLSI document EP28-A3c [16]