Urinary thyroid hormone parameters test for evaluating the thyroid function during pregnancy

Figures & data

Table 1. Levels of thyroid hormones in serum and urine at four different gestational ages.

Group	Gestational age (weeks)	median	25th percentiles (P25)	75th percentiles (P75)
sFT3 (pmol/L)	t1	4.554^b,c,d	4.278	4.919
	t2	4.147^a,c,d	4.001	4.654
	t3	3.448^a,b	3.283	3.844
	t4	3.510^a,b	3.276	3.963
uFT3/uRBP (mg/g)	t1	0.338^c,d	0.277	0.449
	t2	0.323^c,d	0.255	0.451
	t3	0.257^a,b,d	0.187	0.350
	t4	0.183^a,b,c	0.132	0.268
sFT4 (pmol/L)	t1	15.125^b,c,d	13.773	16.122
	t2	13.837^a,c,d	12.750	15.028
	t3	11.694^a,b,d	11.022	12.251
	t4	12.222^a,b,d	10.841	13.258
uFT4/uRBP (mg/g)	t1	0.211^d	0.153	0.282
	t2	0.175^d	0.126	0.313
	t3	0.160^d	0.104	0.222
	t4	0.117^a,b,c	0.081	0.155
sTSH (mIU/L)	t1	1.515^b,c,d	1.015	2.043
	t2	2.085^a,d	1.628	2.545
	t3	2.080^a,d	1.630	2.710
	t4	2.520^a,b,c	2.105	3.475
uTSH/uRBP (IU/g)	t1	0.454^b,c	0.283	0.781
	t2	0.830^a,c,d	0.426	1.099
	t3	0.621^a,b,d	0.455	0.859
	t4	0.432^b,c	0.307	0.799

^acompared with gestational age range 9 to 12 weeks (t₁), p < 0.05; ^bcompared with gestational age range 14 to 17 weeks (t₂), p < 0.05; ^ccompared with gestational age range 23 to 26 weeks (t₃), p < 0.05; ^dcompared with gestational age range 37 to 40 weeks (t₄), p < 0.05; serum free triiodothyronine (sFT3); the ratio of urine FT3 and retinol binding protein (uFT3/uRBP); serum FT4 (sFT4); the ratio of uFT4 and uRBP (uFT4/uRBP); serum TSH (sTSH); the ratio of urine TSH and uRBP (uTSH/uRBP).

Figure 1. The levels of maternal thyriod hormones in serum and urine during pregnancy. The y-axis showed the levels of maternal sFT3 (A), sFT4 (B), sTSH (C), uFT3/uRBP (D), uFT4/uRBP (E), and uTSH/uRBP (F), respectively. The t₁, t₂, t₃, and t₄ of x-axis represented the 9–12, 14–17, 23–26, and 37–40 weeks of gestation, respectively. Each point corresponds to the median level of individual specimen obtained at each gestational age range. The P75 and P25 represented the 75th and 25th percentile of them, respectively. sFT3: serum free triiodothyronine; sFT4: serum FT4; sTSH: serum TSH; uFT3/uRBP: the ratio of urine FT3 and retinol binding protein; uFT4/uRBP: the ratio of uFT4 and uRBP; uTSH/uRBP: the ratio of uTSH and uRBP.

Figure 2. Correlation of thyroid hormones in serum and urine during pregnancy. A) Correlation of sFT3 and uFT3/uRBP, B) Correlation of sFT4 and uFT4/uRBP, and C) Correlation of sTSH and uTSH/uRBP. Study ID presents the serial number of subjects; r presents the Pearson correlation coefficient; Overall (the last row of the results) showed the pooled correlation coefficients and corresponding 95% confidence intervals. sFT3: serum free triiodothyronine; uFT3/uRBP: the ratio of urine FT3 and retinol binding protein; sFT4: serum FT4; uFT4/uRBP: the ratio of uFT4 and uRBP; sTSH: serum TSH; uTSH/uRBP: the ratio of uTSH and uRBP.