Table 3.

Differences in mean TSH and mean FT₄ values with patients divided into four age groups

Age groups (yr)	Number	TSH				FT4
		Mean (mIU/liter)	Log-transformed mean TSH	sd (mIU/liter)	P value (for differences between age groups)	Mean (ng/dl)	sd (ng/dl)	P value (for differences between age groups using Kruskal-Wallis test)
Spontaneous hypothyroidism
<35	32	69	1.83	82	0.45a	0.82	0.41	0.16a
35–49	38	49	1.69	92		0.81	0.31
50–64	30	43	1.63	39		0.67	0.35
>64	12	29	1.46	22		0.68	0.30
Iatrogenic hypothyroidism
<35	28	156	2.19	98	<0.0001b	0.23	0.09	0.94a
35–49	40	115	2.06	70		0.24	0.11
50–64	30	74	1.86	31		0.23	0.07
>64	14	46	1.66	20		0.22	0.09

^aKruskal-Wallis test. 

^bANOVA.