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Background: Age-related changes in testosterone levels in older persons and especially in women have not been fully explored. The objective of this study was to describe age-related trajectories of total testosterone (TT), ammonium sulfate precipitation-measured bioavailable testosterone (mBT), and sex hormone-binding glycoprotein (SHBG) in men and women from the Baltimore Longitudinal Study of Aging, with special focus on the oldest adults.Methods: Participants included 788 White men and women aged 30-96 years with excellent representation of old and oldest old, who reported not taking medications known to interfere with testosterone. Longitudinal data were included when available. TT, mBT, and SHBG were assayed. Age-related trajectories of mBT were compared with those obtained using calculated bioavailable testosterone (cBT). Generalized least square models were performed to describe age-related trajectories of TT, mBT, and SHBG in men and women.Results: mBT linearly declines over the life span and even at older ages in both sexes. In men, TT remains quite stable until the age of 70 years and then declines at older ages, whereas in women TT progressively declines in premenopausal years and slightly increases at older ages. Differences in age-related trajectories between total and bioavailable testosterone are only partially explained by age changes in SHBG, whose levels increases at accelerated rates in old persons. Noteworthy, although mBT and cBT highly correlated with one another, mBT is a much stronger correlate of chronological age than cBT.Conclusion: In both men and women, mBT linearly declines over the life span and even at old ages. Its relationship with age-related phenotypes should be further investigated. [ABSTRACT FROM AUTHOR]

Background: Emerging evidence suggests that mildly down-regulated thyroid function in older persons may protect and/or reflect maintained health.Methods: Using observational data collected between January 2006 and March 2014 on a volunteer sample of 602 men and women aged 68-97 years with normal thyroid function participating in the Baltimore Longitudinal Study of Aging, this study examines the concurrent relationship between reported walking ability, usual and rapid gait speed, endurance walk performance, fatigability, and reported energy level with respect to free thyroxine (FT4) within the normal range (0.76-1.50ng/dL) as a continuous variable and categorized as low (lower quartile), medium (interquartile), or high (upper quartile).Results: Adjusting for sex, age, race, height, weight, exercise and smoking, reported walking ability, usual and rapid gait speed, 400-m time, fatigability, and reported energy level were less favorable with increasing FT4 (p = .013 to <.001). In sex-strata, similar associations were observed except for walking ability in men and energy level in women. Categorical analyses revealed that persons with low FT4 exhibited better functional mobility, fitness, and reported energy than persons with intermediate or high levels (p < .05 for all). Persons with high-normal versus medium FT4 had slower usual and rapid gait speed (p < .05) only.Conclusion: Older adults with low-normal FT4 exhibit better mobility, fitness, and fatigue profiles. Mildly down-regulated thyroid function appears to align with better function in old age and may serve as a biomarker of healthy longevity. [ABSTRACT FROM AUTHOR]

Aims: Abdominal fat is a major determinant of metabolic diseases in older individuals. Obesity and diabetes are associated with low serum amylase (SA) levels, but the association between SA and metabolic disease is poorly understood. We investigated the association of low SA with diabetes and sex-specific associations of serum amylase with abdominal fat in older adults.Methods: In community-dwelling volunteers from the Baltimore Longitudinal Study of Aging (778 participants, age 66.8±13.6years), we assessed abdominal fat by computed tomography and diabetes status using the American Diabetes Association criteria. Linear regression analyses assessed the cross-sectional associations between abdominal fat and SA, and logistic regression assessed the odds of diabetes, given low SA.Results: In unadjusted analyses, individuals in the lowest SA quartile (<48μ/L) had 1.97 greater odds of diabetes, (95%CI, 1.01-3.83) than those in the highest quartile (⩾80μ/L). This association was no longer significant after adjusting for visceral adipose tissue area (VAT, dm(2)), abdominal subcutaneous adipose tissue (SAT, dm(2)) or BMI. In adjusted analyses, VAT and SAT were significantly associated with SA in both sexes. Among women, SA was more strongly associated with VAT than with SAT or BMI; VAT (β=-0.117±0.048, P<0.001), SAT (β=-0.023±0.025, P=0.346) and BMI (β=-0.0052±0.075, P=0.49).Conclusions: The association between SA and diabetes was explained mainly by abdominal visceral fat. In women, SA was more strongly associated with VAT than with BMI or SAT. These findings provide motivation for future mechanistic studies on SA's role in metabolic diseases. [ABSTRACT FROM AUTHOR]

Context: The relationship of fibroblast growth factor 21 (FGF21) with glucose metabolism and insulin resistance has not been well characterized in community-dwelling adults., Objective: The objective of the study was to examine the relationship of FGF21 with glucose metabolism and insulin resistance., Design: Serum FGF21, fasting plasma glucose (FPG), glucose tolerance, and insulin resistance were measured in a cross-sectional study, 2002-2007., Setting: The study was the Baltimore Longitudinal Study of Aging, a natural history cohort study of aging in community-dwelling men and women., Participants: Seven hundred adults, mean age 63.3 yr, participated in the study., Main Outcome Measures: FPG, 2-h plasma glucose, homeostasis model of insulin resistance, whole-body insulin sensitivity (Matsuda index), glucose area under the curve (AUC), and insulin AUC were measured., Results: Overall, the median (25th and 75th percentiles) FGF21 concentration was 225 (126, 370) pg/ml. The proportion of adults with normal, impaired, and diabetic FPG was 77.0, 21.4, and 1.6%, and those with normal, impaired, and diabetic 2-h plasma glucose was 76.7, 19.1, and 4.1%, respectively. Log serum FGF21 (picograms per milliliter), per 1 sd increase, was associated with an FPG (odds ratio 1.43, 95% confidence interval 1.15, 1.77, P = 0.001) and with 2-h plasma glucose (odds ratio 1.39, 95% confidence interval 1.12, 1.73, P = 0.003), in respective multivariate, ordered logistic regression models, adjusted for potential confounders. Serum FGF21 (picograms per milliliter) was associated with the homeostasis model of insulin resistance, the Matsuda index, glucose AUC, and insulin AUC (all P < 0.0001) in respective multivariable linear regression models adjusted for potential confounders., Conclusions: Higher serum FGF21 concentrations were associated with abnormal glucose metabolism and insulin resistance in community-dwelling adults.