Table 3.

Geometric means and 95 % confidence intervals of IGF-1 (ng/mL) concentrations by quintiles of sex steroid hormones in the U.S. male population of 20 years or older, NHANES III 1988–1991

Sex steroid hormones	Model 1†		Model 2†		Model 3§
	Mean	95 % CI	Mean	95 % CI	Mean	95 % CI
Total testosterone (ng/mL)
≤3.67	276	259–293	282	270–294	271	256–289
3.68–4.64	248	226–271	252	227–279	245	222–270
4.65–5.62	283	260–307	281	259–306	279	258–303
5.62–6.91	276	262–291	274	259–289	278	262–294
>6.91	283	258–310	278	257–300	291	267–317
Slope, P-trend*	0.02	0.22	0.01	0.70	0.02	0.13
Free testosterone (ng/mL)
≤0.069	277	253–304	278	258–300	273	252–295
0.070–0.092	270	248–293	272	245–301	269	242–298
0.093–0.113	261	244–279	263	247–280	262	245–279
0.113–0.14	280	262–298	277	260–296	278	261–297
>0.14	279	252–309	277	254–303	283	260–309
Slope, P-trend*	0.01	0.66	0.01	0.80	0.01	0.44
Total estradiol (pg/mL)
≤28.56	292	278–306	288	273–302	290	274–306
28.57–33.29	269	258–281	265	252–277	265	252–278
33.30–38.66	265	249–282	269	252–288	269	252–288
38.67–46.2	287	257–320	287	258–318	286	257–317
>46.2	257	237–279	261	242–281	259	241–279
Slope, P-trend*	−0.02	0.17	−0.01	0.38	−0.01	0.28
Free estradiol (pg/mL)
≤0.70	280	269–292	272	260–285	276	262–291
0.71–0.85	282	268–296	276	263–290	278	265–292
0.86–1.0	265	244–288	266	246–288	267	246–289
1.1–1.2	281	268–295	285	271–301	284	270–298
>1.2	259	232–290	266	240–294	262	238–288
Slope, P-trend*	−0.02	0.26	−0.002	0.89	−0.01	0.52
SHBG (nmol/L)
≤24.0	272	250–296	278	255–303	282	255–311
24.1–31.6	270	253–289	274	257–292	275	256–296
31.7–40.52	270	256–284	271	258–285	271	258–284
40.53–53.5	283	267–301	277	263–293	275	261–290
>53.5	271	252–293	262	242–285	260	237–286
Slope, P-trend*	0.005	0.67	−0.01	0.51	−0.02	0.39
Androstanediol glucuronide (ng/mL)
≤6.72	275	262–289	274	261–287	Not applicable
6.73–9.68	283	267–301	284	268–302
9.69–12.77	256	237–277	258	235–283
12.78–17.82	268	252–286	270	253–287
>17.82	283	264–303	280	262–299
Slope, P-trend*	0.002	0.88	0.001	0.96

SHBG sex hormone-binding globulin

^†From a weighted linear regression model of sex steroid hormones on IGF-1 adjusted for age and race/ethnicity

^‡Same as model 1 plus adjustment for body mass index, waist circumference, diabetes, alcohol consumption, cigarette smoking, and physical activity

^§Same as model 2 plus testosterone, estradiol, and SHBG mutually adjusted, and free testosterone and free estradiol mutually adjusted

^*Change in IGF-1 concentration in ng/mL per one quintile change in sex steroid hormone concentration