Hormones and Aging
• Most hormonal axes are associated with a gradual age related changes over time, beginning at about age 30 years, with the exception of a relatively rapid decline in estradiol during the menopause transition in women.
• Serum total testosterone concentrations decrease gradually with age in men, but numerous other factors could be contributing to the decline, including age-related chronic disease and lifestyle.
• By age 70 years, dehydroepiandrosterone, a precursor for androgens and estrogens, is ∼20% of peak levels observed in the third decade of life.
• The decline in growth hormone (GH) with aging is accompanied by changes in body composition; however, whether GH declines contribute to age-related metabolic changes, sleep disturbances and visceral adiposity or vice versa is unknown.
• Age-specific reference ranges for thyroid-stimulating hormone may be appropriate and have important implications in defining subclinical hypothyroidism in older adults.
1. Estrogen therapy is controversial but is indicated as first-line therapy for relief of postmenopausal vasomotor and genitourinary symptoms, and may be considered as a primary therapy in women with an elevated risk for bone loss and fractures, as well as those with hypoestrogenism caused by hypogonadism, surgical menopause, or premature ovarian insufficiency. There may be cardiovascular benefits if therapy is initiated early (near time of menopause).
2. Testosterone therapy for older symptomatic hypogonadal men is associated with consistent improvements in body composition (decreased fat and increased fat-free mass), but instituting therapy requires close patient monitoring, especially in regard to cardiovascular status. Consistent evidence for improvement in strength or function is not available. Testosterone therapy is indicated for men with signs and symptoms of androgen deficiency and confirmed low morning serum testosterone levels.
3. DHEA replacement therapy increases levels of estradiol, testosterone (women only), insulin-like growth factor-1 (IGF-1) and bone mineral density, but does not appear to be associated with clear improvements in metabolism or body composition in older humans.
4. Growth hormone supplementation appears to be more effective at increasing lean body mass in older men than in older women. These body compositional changes are not necessarily associated with functional improvements and treatment has been associated with risk of adverse events.
5. Physical activity and long-term caloric restriction have the best evidence for alleviating age-related increases in adiposity, reductions in lean body mass, and cardiovascular risk factors.
6. Weight loss in the obese elderly is associated with improvements in cardiovascular risk factors, but exercise may be needed to attenuate loss of muscle and bone mass during weight loss, and to mitigate against frailty.
7. Adequate calcium and vitamin D intake are essential for fall and fracture prevention and maintenance of bone mineral density.
8. Clinicians caring for older adults with type 2 diabetes must take into consideration the clinical and functional heterogeneity of their patients when setting and prioritizing an individual’s treatment goals and drug regimens. Occult hypoglycemia may be much more common in older patients, especially those treated with insulin, and the consequences of this on central nervous system and cardiovascular function must be carefully considered.