Objective: to compare ageassociated 8-
Annual changes in total testosterone, bioavailable testosterone, and sex hormone binding immunoglobulin (SHBG)
Five groups of men were stratified according to changes in body mass index (BMI)(i. e. , BMI stable (±0. 69u2009kg/m2), decreased (−0. 7u2009kg/m2)
Minimum increase (0. 7–1. 74u2009kg/m2)
Increase moderately (1. 75–3. 19u2009kg/m2)
And increase most (ue2f63. 20u2009kg/m2)). Design:Eight-
Longitudinal cohort study of the year.
Subject: 470-
When the hormone was first measured, four black men aged 24-31 and 695 white men.
Size: Aging-
Changes in serum SHBG, total testosterone and bioavailable testosterone.
Results: for men with a decrease in BMI, SHBG increased significantly with age, and for men with a stable BMI, or men with a minimum or moderate increase in BMI, the increase in SHBG decreased graduallyrange 1. 1–0.
3 u2009 nM every year P ue2fa 0.
03 points).
Men with the most increase in BMI had no age relationship with SHBG.
For men with a decreased, stable, or minimal increase in BMI, total testosterone does not change with age, but for men with a moderate increase in BMI, the total testosterone in most men decreases gradually with ageβ=−0. 2 and −0.
4 u2009 nM every year respectively P ue2fa 0. 005).
In all groups, however, bioavailable testosterone declined to a similar level as age increased.
Conclusion: These results suggest that age is regulated by changes in BMI during adolescence
A related change in SHBG and total testosterone, but no bioavailable testosterone.
There is a lot of research on the cardiac
Center, to study longitudinal studies of physiological, psychological and lifestyle factors that may affect the development of cardiovascular disease risk factors in young black and white men and women.
In short, 5115 participants aged 18-30 completed baseline examinations in 1985, and 1986 participants completed baseline examinations in one of the four clinical centers in Birmingham, Alabama;
Chicago, Illinois;
Minneapolis, Minnesota or Oakland, California. Four follow-
The up exam was completed in 198-1987 (year 2), 1990–1991 (year 5), 1992–1993 (year 7)and 1995–1996 (year 10).
A detailed description of the design, recruitment and methodology of this study was published prior to this.
The number of black and white men who completed the baseline examination was 1157 and 1171, respectively.
For CMHS, hormone concentrations were measured in serum collected for 2, 7 years (when available)
10 more exams.
Because the main goal of this study is to evaluate 8-
The annual longitudinal change in serum hormone levels only included men with serum at least 2 years and 10 years of examination, I . e. 624 black and 796 White.
Of the 1420 men, 1211 received serum from a seven-year examination.
We ruled out two black men because they had a baseline age of over 31 years.
In the CMHS data previously released, we showed that for black and white men, the total testosterone in men aged 22-23 was higher than in men aged 20-21, whereas after 24, the concentration of testosterone seems to have decreased.
Since the relationship between the age of young men and total testosterone concentrations reversed compared to older men, we excluded 139 black and 101 white men aged 20-23 from all analyses.
In addition, we excluded 9 black males with missing BMI data for 2 or 10 years.
The final sample size of the analysis included 474 black and 695 white people aged 24 and over.
CMHS has been approved by the Institutional Review Committee of Northwestern University.
In the CARDIA study, all data collection technicians were centrally trained and certified.
The CARDIA coordination center and the CARDIA Quality Control Board monitored data collection throughout the course of the study.
Each check was informed consent from each participant.
Participants were asked to fast for 12 hours before each exam.
Weight and height were measured using a balance wood scale and a vertical ruler, carpenter's square or stadiometer, with participants wearing lightweight clothes and no shoes.
The height is recorded to the nearest 0.
5 cm, weight to the nearest 0. 5u2009lb.
BMI is calculated by weight (kg)
Divided by the square of height (m).
Repeated measurements of waist circumference under minimal abdominal circumference.
Age, race and years of educationreported. Other self-
The Information reported includes the use of prescription drugs.
A subset of drugs may affect levels of steroid hormone or steroid hormone
And/or interfere with steroid hormone binding.
Therefore, there are two categories of drugs :(1)
Regulation or interference of known or possible constraints, and (2)
Unlikely.
In each of the three examinations, blood was collected by intravenous puncture from more than 0730 of CMHS participants within 1200 to 95% hours.
Serum aliquot were stored at-70 °c within 90 minutes of blood draw.
The sample is packed with dry ice and shipped to a long
Long-term frozen storage facilities.
The samples used in this study have not been thawed before.
Total testosterone was directly determined by radioimmunity kit, and SHBG was determined by Immulite chemical luminous enzyme immune assay (
Los Angeles diagnostic products, USA).
All samples of each individual are analyzed in the same batch.
The variability of the analysis was monitored by including 10% of the blind quality control samples in each batch of samples analyzed.
The quality control serum was obtained from a large pool, which was placed equally into the storage vial and marked as identical to the sample of the CARDIA participant. The intra-and inter-
12 batch technical errors. 3 and 11.
Total testosterone was 2% and 7, respectively. 9 and 11.
SHBG was 2%, respectively.
The concentration of bioavailable testosterone is calculated according to the method of södergardthe age-and BMI-
The adjusted partial correlation between blood draw time and all hormone levels was 4. 1. 0. 09.
Therefore, the relationship between blood draw time and hormone level was not considered further.
Serum testosterone and SHBG concentrations in black and white men appeared to be distributed normally.
Participants were stratified according to their change in BMI during the 2 to 10 year exam.
We defined the BMI stabilization group (Reference group)
Those men with a BMI change of less than 0.
Between 2 and 10 years is 7 kilograms/meter.
The second group included men with a BMI drop of 0. More than 7 catties/meters (i. e. , BMI loss).
The rest of the men, their BMI at 8-
During the year, it was divided into about three equal parts.
We define these three groups as BMI minimum gain group, medium gain group and maximum gain group.
Displays the cutting points for each group.
In the preliminary analysis, we examined the distribution of black and white men in five BMI-changing groups.
We also calculated the average age of men in each group during the two-year and 10-year exams.
2 and 10and race-
Using covariable analysis, the adjusted mean BMI of the stable group was compared with the adjusted mean BMI of other BMI change groups (ANCOVA).
Use ANCOVA, minimum 2 years, 7 years and 10 years-
The square average concentration of SHBG, total testosterone and bioavailable testosterone per BMI Group was calculated and adjusted according to age, BMI and race.
To better understand 8-
We use the Generalized Estimation equation (GEE)
Analyze and calculate the regression coefficient of the overall average annual change of hormone adjustment to 2 years old and time
Independent BMI and race for each BMI change group.
Because black and white men have no meaningful differences in the overall average annual change in hormone levels, we combine black and white for analysis.
The main analysis focuses on aging-
Changes in SHBG, total testosterone, and bioavailable testosterone in the BMI change group.
Again, there are no black and white differences in these results, so we only provide results for joint analysis.
We used a long term change that included race, BMI for the second year (i. e.
Those changes that do not belong to age)
Between 2 and 7 years, and between 2 and 10 years, time-
The associated age and dummy variables of the four BMI change groups, where the reference group is the BMI stable group, we include these dummy variables and time-dependent age. The -
The coefficient of the interaction term is used to determine the size of the mean age difference
Related changes in hormone levels relative to the BMI stable group and each BMI change category, and-
The value of the interaction item is used to evaluate the statistical significance level of this difference.
In addition, including time-
Drug-dependent indicator variables classified as "possibilities" to regulate or interfere with male hormone binding did not change the Association of hormones with race, age or obesity measures.
Therefore, the results are given without adjusting the use of the drug.
All analyses are performed using SAS version 9. 1 (
SAS Institute LimitedCary, North Carolina, United States).
For longitudinal analysis, proc genmod is used and the switchable structure is specified internally
Topic Association.