Male subclinical hypogonadism and late-onset hypergonadotrophic hypogonadism: mechanisms, endothelial function, and interplay between reproductive hormones, undercarboxylated osteocalcin, and endothelial dysfunction

Figures & data

Figure 1. Undercarboxylated osteocalcin levels in the studied group. Box plot of undercarboxylated osteocalcin among healthy eugonadal, subclinical hypognadism and late onset hypogonadism groups. Each box indicates the 25th and 75th percentiles, the median is represented by the horizontal line within the box, the extreme measured values are indicated by whiskers. Dots and stars represent the outliers.

A box plot graph shows three boxes that represent serum undercarboxylated levels in healthy eugonadal, subclinical hypognadism and late onset hypogonadism groups. Subclinical hypogonadism and late-onset hypogonadism groups had comparable undercarboxylated levels meanwhile subclinical hypogonadism group has significantly higher undercarboxylated levels than healthy eugonadal subjects.

Table 1. Clinical, laboratory, and endothelial function parameters of the groups studied.

Variables	Late onset hypogonadism (LOH, n = 60)	Subclinical hypogonadism (SCH, n = 76)	Healthy euogonadism (HE, n = 50)	p value
				All groups ANOVA	LOH versus SCH	LOH versus HE	SCH versus HE
Age (years)^a	57.1 ± 4	56.7 ± 4.6	57.8 ± 5.1	0.48	0.59	0.76	0.25
Smoker n (%)^b	25 (83.3%)	24 (63.2%)	16 (64%)	0.16	0.10	0.10	0.9
BMI (kg/m^2)^a	23.4 ± 3.2	23.4 ± 3.2	23.4 ± 3.1	0.98	0.92	0.86	0.86
SBP (mmHg)^a	123.6 ± 14.3	123 ± 12.6	114 ± 9.7	0.95	0.978	0.09	0.09
DBP (mmHg)^a	84.4 ± 7.8	81.8 ± 8	75.8 ± 4.9	0.22	0.371	0.06	0.08
FBS (mg/dl)^a	96.5 ± 13.1	89.4 ± 12.8	89.9 ± 5.7	0.001	0.002	0.003	0.81
PPBS (mg/dl)^a	152.2 ± 7.1	154.5 ± 15.1	137.2 ± 13.9	0.47	0.13	0.23	0.14
Cholesterol (mg/dl)^a	192.3 ± 17.4	195.7 ± 18.5	166.7 ± 18.6	<0.001	0.27	<0.001	<0.001
Triglyceride (mg/dl)^a	205.9 ± 11.9	205.6 ± 12.3	145.7 ± 34.6	<0.001	0.89	<0.001	<0.001
LDL-c (mg/dl)^a	131.4 ± 17.5	131.4 ± 15.4	114.7 ± 14.5	0.003	0.97	<0.001	<0.001
HDL-c (mg/dl)^a	43.2 ± 4.1	43.2 ± 4.6	48.3 ± 6	<0.001	0.98	<0.001	<0.001
LH (IU/l)^c	14.1 (11.9–16.6)	20.6 (13.4–24.6)	7.1 (5.8–8.9)	<0.001	<0.001	<0.001	<0.001
FSH (nmol/l)^c	15.4 (11.2–17.7)	9.7 (4.4–11.1)	7.6 (4.2–10.4)	<0.001	<0.001	<0.001	0.88
Testosterone (nmol/l)^c	4.9 (3.8–5.5)	23.5 (16.5–25.9)	21.7 (15.8–24.8)	<0.001	<0.001	<0.001	0.22
Estradiol (nmol/l)^c	2.8 (0.9–6.6)	3.1 (2.6–4.7)	3.8 (1.7–8.2)	0.009	0.008	0.83	0.01
SHBG (nmol/dL)^c	247 (215–281)	199.5 (171–220)	203.5 (136–244)	<0.001	<0.001	<0.001	0.78
Free Androgen index (pmol/l)^c	113 (82– 135)	700 (480–780)	630 (447–710)	<0.001	<0.001	<0.001	0.92
LH/T ratio^c	3.5 (2.2–3.8)	0.9 (0.6–1.3)	0.3 (0.2–0.5)	<0.001	<0.001	<0.001	<0.001
ASI (LH × T product)^c	66 (50–74)	456 (246–590)	133 (101–187)	<0.001	<0.001	<0.001	<0.001
Corrected ASI	5.7 (4.5– 6.5)	39.6 (21.6– 51.3)	11.6 (8.8– 16.2)	<0.001	<0.001	<0.001	<0.001
E/T ratio^c	0.74 (0.27–2)	0.08 (0.04–0.21)	0.17 (0.07–0.39)	<0.001	<0.001	<0.001	0.005
ucOC (nmol/l)^c	249 (181–453)	292 (212–403)	212 (184.3–260)	0.001	0.46	0.03	0.001
hsCRP (mg/l)^c	4.5 (2.1–8.4)	4.8 (1.7–9.3)	1.2 (0.44–3)	<0.001	0.82	<0.001	<0.001
FMD %^c	5.7 (5.6–6.1)	5.6 (2.7–5.9)	11.6 (10–12.8)	<0.001	0.08	<0.001	<0.001
CIMT (mm)^a	0.9 ± 0.1	0.9 ± 0.1	0.65 ± 0.1	<0.001	0.90	<0.001	<0.001
Aortic stiffness index^a	18 ± 1.5	18.5 ± 1.7	12.7 ± 1.6	<0.001	0.397	<0.001	<0.001

BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBS: fasting blood sugar; PPBS: 2 h postprandial blood sugar; LDL-c: low-density lipoprotein cholesterol; HDL-c: high-density lipoprotein cholesterol; LH: luteinizing hormone; FSH: follicle stimulating hormone; SHBG: sex hormone binding globulin; T: testosterone; E: estradiol; ASI: androgen sensitivity index; ucOC: undercarboxylated osteocalcin; hsCRP: high sensitive C reactive protein; FMD%: brachial artery flow mediated dilation percentage; CIMT: carotid artery intimal medial thickness. tatistically signficant values are written in bold.

^aParametric quantitative data are expressed as mean ± SD and compared using one-way ANOVA test for comparison between the three groups followed by the post hoc Tukey analysis between two groups.

^bQualitative data are expressed as a percentage and compared using the Chi-square test.

^cNon-parametric quantitative data are expressed as median (25–75% interquartile range) and compared using the Kruskal–Wallis test between the three groups followed by the Mann–Whitney test between two groups. Significant level at p value < 0.05.

Table 2. Correlation between reproductive hormone levels, hypothalamo-pituitary testicular axis regulatory factors (LH/T, LH × T, and E/T ratio) and undercarboxylated osteocalcin on the one hand and studied cardiovascular risk factors and endothelial function parameters on the other hand, in all study subjects.

	LH (IU/l)	FSH (nmol/l)	T (nmol/l)	E (nmol/l)	SHBG (nmol\l)	FAI	LH/T ratio	LH × T product	E/T ratio	ucOC (nmol/l)
Age (years)	0.01	−0.15	0.001	−0.9	0.06	−0.03	−0.003	−0.01	−0.1	−0.11
BMI (kg/m^2)	0.09	−0.08	−0.02	0.16*	−0.05	0.02	0.06	0.005	0.11	0.02
SBP (mmHg)	0.08	−0.02	−0.04	−0.01	0.05	−0.06	−0.03	−0.08	0.004	0.09
DBP (mmHg)	0.01	0.09	−0.26***	0.01	0.13	−0.27***	0.21**	−0.11	−0.03	0.15*
FBS (mg/dl)	−0.11	0.23**	−0.22**	0.12	0.2**	−0.22**	0.28***	−0.22**	0.23**	0.03
PPBS (mg/dl)	0.06	−0.11	0.14	−0.06	0.05	0.19**	−0.09	0.13	0.12	−0.02
Cholesterol (mg/dl)	0.26***	0.09	−0.15*	−0.01	0.09	−0.18*	0.28***	0.03	0.07	0.31***
Triglyceride (mg/dl)	0.33***	0.07	−0.13	−0.09	0.08	−0.16*	0.26***	0.06	0.03	0.12
LDL-c (mg/dl)	0.05	−0.08	−0.12	−0.11	0.06	−0.11	0.1	0.02	0.01	0.13
HDL-c (mg/dl)	−0.18*	−0.12	0.16*	−0.04	0.04	0.13	−0.24**	−0.01	−0.13	−0.12
hsCRP (mg/l)	0.33***	0.07	−0.07	−0.04	0.27***	−0.2**	0.28***	0.09	0.08	0.22***
ucOC (nmol\l)	0.31***	0.14	0.12	0.16*	0.38***	−0.18*	0.22**	0.14	0.13	NA
FMD %	−0.55***	−0.10	0.18*	0.1	−0.12	0.18*	−0.43***	−0.13	−0.003	−0.18*
CIMT (mm)	0.55***	0.19**	−0.16*	−0.01	0.01	−0.44***	0.45***	0.13	0.06	0.16*
Aortic stiffness index	0.43***	0.01	−0.02	−0.26 ***	0.01	−0.47***	0.35***	0.14	−0.17*	0.1

BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBS: fasting blood sugar, PPBS: 2 h postprandial blood sugar; LDL-c: low-density lipoprotein-cholesterol; HDL-c: high-density lipoprotein-cholesterol; LH: luteinizing hormone; FSH: follicle stimulating hormone; T: testosterone; E: estradiol; SHBG: sex hormone binding globulin; FAI: Free Androgen index; ucOC: undercarboxylated osteocalcin; hsCRP: highly sensitive C-reactive protein; FMD%: brachial artery flow mediated dilation percentage; CIMT: carotid artery intimal medial thickness.

Correlation coefficients r are assessed and written in the table using Spearman’s correlation. Significant correlation coefficients are given in bold, ***p < 0.001; **p < 0.01; *p < 0.05.

Table 3. Correlation between reproductive hormone levels, hypothalamo-pituitary testicular axis regulatory factors (LH/T, LH × T, and E/T ratio) and undercarboxylated osteocalcin on the one hand and studied cardiovascular risk factors and endothelial function parameters on the other hand in the subclinical hypogonadism group.

	LH (IU/l)	FSH (nmol/l)	T (nmol/l)	E (nmol\l)	SHBG (nmol\l)	FAI	LH/T ratio	LH × T product	E/T ratio	ucOC (nmol\l)
Age (years)	0.39***	−0.19	0.02	0.04	−0.09	−0.03	0.23*	0.31**	−0.04	−0.11
BMI (kg\m^2)	0.21	−0.21	−0.04	0.07	0.05	−0.06	0.05	0.12	0.03	0.02
SBP (mmHg)	−0.08	−0.06	0.05	−0.05	0.18	0.02	−0.005	0.03	−0.06	0.33**
DBP (mmHg)	−0.09	−0.22	−0.14	−0.15	0.1	−0.02	0.10	−0.02	−0.08	0.35**
FBS (mg/dl)	−0.02	0.14	0.21	0.21	0.16	0.21	−0.13	0.01	0.15	0.09
PPBS (mg/dl)	0.04	0.11	0.02	0.07	0.11	0.02	0.08	0.11	0.08	0.16
Cholesterol (mg/dl)	−0.08	−0.14	−0.22	0.02	0.02	−0.19	0.05	−0.19	0.11	0.29*
Triglyceride (mg/dl)	0.09	0.08	−0.21	−0.05	−0.17	−0.22	0.22	−0.06	−0.02	−0.12
LDL-c (mg/dl)	−0.14	0.21	−0.07	−0.25*	0.28*	−0.01	−0.11	−0.09	−0.27*	0.21
HDL-c (mg/dl)	0.09	−0.14	0.15	−0.16	0.03	0.15	0.007	0.22	0.23*	0.11
hsCRP (mg/l)	−0.04	−0.03	−0.06	0.18	0.18	−0.08	0.003	−0.13	−0.25*	0.15
ucOC (nmol/l)	0.12	0.03	−0.05	0.06	0.38**	−0.11	0.14	0.11	0.11	NA
FMD %	−0.02	−0.06	0.29*	0.02	−0.02	0.31**	−0.21	0.21	−0.03	0.13
CIMT (mm)	0.06	0.07	0.07	0.21	0.07	0.09	−0.15	0.04	0.2	−0.11
Aortic stiffness index	0.01	−0.06	−0.07	−0.14	−0.19	−0.06	0.02	−0.03	−0.12	0.005

BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBS: fasting blood sugar, PPBS: 2 h postprandial blood sugar; LDL-c: low-density lipoprotein-cholesterol; HDL-c: high-density lipoprotein-cholesterol; LH: luteinizing hormone; FSH: follicle stimulating hormone; T: testosterone; E: estradiol; SHBG: sex hormone binding globulin; FAI: Free Androgen index; ucOC: undercarboxylated osteocalcin; hsCRP: highly sensitive C-reactive protein; FMD%: brachial artery flow mediated dilation percentage CIMT: carotid artery intimal medial thickness.

Correlation coefficients r are assessed and written in the table using Spearman’s correlation. Significant correlation coefficients are given in bold, ***p < 0.001; **p < 0.01; *p < 0.05.

Table 4. Correlation between reproductive hormone levels, hypothalamo-pituitary testicular axis regulatory factors (LH/T, LH × T, and E/T ratio) and undercarboxylated osteocalcin on the one hand and studied cardiovascular risk factors and endothelial function parameters on the other hand in the late-onset hypogonadism group.

	LH (IU/l)	FSH (nmol/l)	T (nmol/l)	E (nmol\l)	SHBG (nmol\l)	FAI	LH/T ratio	LH × T product	E/T ratio	ucOC (nmol/l)
Age (years)	0.26*	0.29*	0.06	0.29*	0.07	0.07	0.32*	0.02	0.32*	0.06
BMI (kg/m^2)	0.16	0.09	−0.31*	0.36**	−0.03	0.17	0.25*	−0.11	0.41**	0.16
SBP (mmHg)	0.02	0.16	−0.53***	0.22	−0.08	−0.41**	0.4**	−0.47***	0.36**	−0.06
DBP (mmHg)	−0.001	0.13	−0.26*	0.02	−0.19	0.2	0.25*	−0.34**	0.11	0.17
FBS (mg/dl)	0.18	−0.04	−0.29*	0.17	0.008	−0.21	0.34**	−0.07	0.22	0.03
PPBS (mg/dl)	−0.08	−0.24	−0.35**	−0.13	−0.33**	−0.39**	−0.18	0.11	0.22	−0.21
Cholesterol (mg/dl)	−0.19	0.16	0.17	0.07	0.06	0.12	−0.19	−0.01	0.05	0.15
Triglyceride (mg/dl)	0.19	0.01	−0.36**	0.06	−0.27*	−0.36**	0.14	0.32*	−0.17	−0.14
LDL-c (mg/dl)	0.41**	0.008	0.19	0.001	−0.15	−0.28*	0.51***	0.09	−0.08	0.08
HDL-c (mg/dl)	0.14	0.25	0.11	0.11	0.20	0.02	0.05	0.26*	0.04	0.30*
hsCRP (mg\l)	0.31*	0.13	0.09	0.07	0.04	0.09	0.07	0.42**	−0.009	0.06
ucOC (nmol\l)	0.29*	0.26*	−0.24	0.44***	0.60***	−0.38**	0.19	0.04	0.52***	NA
FMD %	−0.04	0.13	0.22	0.03	−0.43**	0.29*	−0.21	0.01	−0.03	−0.19
CIMT (mm)	0.41**	0.09	−0.08	0.09	−0.09	−0.19	0.01	0.39**	−0.14	0.03
Aortic stiffness index	0.44***	0.34**	0.20	−0.32*	0.03	0.2	0.55***	−0.09	−0.42**	0.30*

BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic blood pressure; FBS: fasting blood sugar, PPBS: 2 h postprandial blood sugar; LDL-c: low-density lipoprotein-cholesterol; HDL-c: high-density lipoprotein-cholesterol; LH: luteinizing hormone; FSH: follicle stimulating hormone; T: testosterone; E: estradiol; SHBG: sex hormone binding globulin; FAI: Free Androgen index; ucOC: undercarboxylated osteocalcin; hsCRP: highly sensitive C-reactive protein; FMD%: brachial artery flow mediated dilation percentage CIMT: carotid artery intimal medial thickness.

Correlation coefficients are assessed and written in the table using Spearman’s correlation. Significant correlation coefficients are given in bold, ***p < 0.001; **p < 0.01; *p < 0.05.

Table 5. Multiple linear regression analysis to assess the role of reproductive hormones, studied hypothalamo-pituitary regulatory factors and undercarboxylated osteocalcin as independent predictors of endothelial function parameters in all study participants.

	Unstandardized coefficients	Standardized coefficients
Dependent predictors	B (Std. error)	Beta	T	p-value
(a) Flow mediated dilation %, R = 0.51, R^2 = 0.26
Constant	10.4 (0.79)		13.1	<0.001
Luteinizing hormone (IU/l)	−0.19 (0.03)	−0.42	−5.9	<0.001
Luteinizing hormone/testosterone	−0.22 (0.17)	−0.11	−0.13	0.21
Free androgen index ( pmol/l)	0.04 (0.03)	0.11	1.34	0.18
Undercarboxylated osteocalcin (nmol/l)	−0.001 (0.002)	−0.06	0.87	0.38
(b) Carotid intima media thickness, R = 0.58, R^2=0.34
Constant	0.62 (0.02)		20.9	<0.001
Luteinizing hormone (IU/l)	0.007 (0.001)	0.43	6.4	<0.001
Follicle stimulating hormone (nmol/l)	0.001 (0.002)	0.05	0.78	0.43
Luteinizing hormone/testosterone	0.01 (0.006)	0.21	2.37	0.02
Free androgen index ( pmol/l)	0.000 (0.001)	0.02	0.29	0.76
Undercarboxylated osteocalcin (nmol/l)	0.001 (0.00)	0.103	1.57	0.11
(c) Aortic stiffness index, R = 0.49, R^2=0.24
Constant	14 (0.44)		31.47	<0.001
Luteinizing hormone (IU/l)	0.18 (0.02)	0.47	6.8	<0.001
Luteinizing hormone/testosterone	0.11 (0.11)	0.06	0.99	0.32
Estradiol (nmol/l)	−0.00 (0.008)	−0.001	−0.02	0.97

Table 6. Multiple linear regression analysis to assess role of reproductive hormones, studied hypothalamo-pituitary regulatory factors and undercarboxylated osteocalcin as independent predictors of endothelial function parameters in the late-onset hypogonadism group.

	Unstandardized coefficients	Standardized coefficients
Dependent predictors	B (std. error)	Beta	T	p-value
(a) Flow mediated dilation %, R = 0.39, R^2=0.15
Constant	10.17 (1.5)		6.4	<0.001
Free androgen index (pmol/l)	0.35 (0.23)	0.25	1.5	0.13
Sex hormone binding globulin (nmol/dl)	−0.013 (0.004)	−0.51	3.06	0.003
(b) Carotid intima media thickness, R = 0.29, R^2=0.08
Constant	0.81 (0.02)		30.4	<0.001
Luteinizing hormone (IU/l)	0.006 (0.003)	0.47	2.11	0.03
Luteinizing hormone testosterone	0.001 (0.001)	−0.27	−1.21	0.22
(c) Aortic stiffness index, R = 0.76, R^2=0.58
Constant	21.8 (0.59)		36.7	<0.001
Luteinizing hormone (IU/L)	0.02 (0.03)	0.08	0.73	0.46
Follicle stimulating hormone (nmol/l)	0.08 (0.26)	0.26	2.6	0.01
Luteinizing hormone/testosterone	0.61 (0.11)	0.73	5.6	<0.001
Estradiol (nmol/l)	−0.18 (0.07)	−4.3	−2.3	0.02
Undercarboxylated osteocalcin (nmol/l)	0.002 ( 0.001)	0.32	2.96	0.004
Estradiol/testosterone	0.84 ( 0.35)	4.56	2.39	0.02

Statistically signficant values are written shown in bold.

Data availability statement

The datasets generated and analyzed during the present study are not publicly accessible due to concerns of participant confidentiality but are offered by the corresponding author on realistic request.