Table 3.

Difference in mean hormone concentrations by age group, comparing NHANES 1988–1991 to 1999–2004.

		1988–1991		1999–2004
	Age	Meana, b	95% CIc	Meana, b	95% CIc	Difference	P-value
Testosterone (ng/ml)	20–44	5.49	5.25, 5.73	5.29	5.03, 5.55	−0.20	0.15
	45–69	5.20	4.95, 5.45	5.38	5.10, 5.67	0.18	0.21
	≥ 70	5.15	4.64, 5.67	5.34	4.77, 5.91	0.19	0.39
Free testosterone (ng/ml)	20–44	0.102	0.096, 0.108	0.103	0.097, 0.109	0.001	0.67
	45–69	0.098	0.089, 0.109	0.095	0.088, 0.103	−0.003	0.55
	≥ 70	0.083	0.071, 0.097	0.073	0.060, 0.089	−0.010	0.19
SHBG (nmol/L)	20–44	35.75	33.38, 38.29	31.69	29.62, 33.90	−4.06	<0.01
	45–69	32.56	30.01, 35.32	35.19	32.17, 38.50	2.64	0.04
	≥ 70	35.54	30.07, 42.01	38.35	32.79, 44.85	2.81	0.13
3α-diol-G (ng/ml)	20–44	12.29	11.40, 13.26	9.80	9.13, 10.52	−2.49	<0.01
	45–69	11.38	10.14, 12.77	10.45	9.56, 11.43	−0.92	0.15
	≥ 70	12.09	9.85, 14.85	10.98	9.21, 13.08	−1.11	0.20
Estradiol (pg/ml)	20–44	35.53	33.70, 37.47	29.45	27.45, 31.60	−6.08	<0.01
	45–69	35.36	32.34, 38.67	29.95	27.74, 32.34	−5.41	<0.01
	≥ 70	38.61	34.23, 43.56	29.98	25.59, 35.13	−8.63	<0.01

^aadjusted for age, race/ethnicity (1 year intervals), BMI, waist circumference, smoking, and alcohol use

^bmeans for free testosterone, SHBG, 3α-diol-G, and estradiol are geometric means

^cCI – confidence interval