Endocrinology of ageing Flashcards
Weight and lean body mass changes with age
Weight increases from mid-30s
- Stays stable 50-70
Lean body mass decreases
- 6-8%, from mid-30s
Diet trend with age
Decrease in intake of total energy
Protein intake increases
Insulin and glucose changes with age
Insulin and glucose increase
- Increase in insulin resistance
- Decrease in peripheral glucose uptake
- Increased prevalence of metabolic syndrome
Metabolic syndrome
Closely related conditions that increase the risk of CVD..
- Visceral obesity
- Dyslipidaemia
- Hypertension
- Hyperglycaemia
Increased prevalence as age increases due to an increase in insulin resistance.
- Generally more prevalent in males
Menopause
- Definition
- Symptoms
- Morbidities
Ovarian failure
- Drop in oestrogen
- Rise in FSH and LH
- Age 50 +/- 2 years
Symptoms
- Hot flushes
- Night sweats
Morbidities
- Osteoporosis
- Coronary heart disease
- Sexual dysfunction
Post-menopausal replacement therapy
- Benefits
Relieves the symptoms
- Decreases risk of osteoporosis and fractures
Post-menopausal replacement therapy
- Risks
- How to resolve it
Venous thrombolism
Breast cancer
- esp. used for >5 years
Endometrial cancer
- Unopposed E2 [only e2]
Resolved by only treating symptoms instead of preventing disorders
- Short term
- Low dose
- Started earlier.
Male gonadal axis with age
Gradual decrease in testosterone but with a wide range of normality.
Poor association with libido/ erectile dysfunction and testosterones.
- Decreased sexual function and muscle strength
- Increase risk of osteoporosis
Effects of testosterone treatment on bones
Increases bone mineral density
- But not their mechanical strength
- Fracture risk decreased by bisphosphanates.
Effects of testosterone treatment on body composition.
Increases lean body mass
Decreases fat mass
Increases muscle strength only in very high doses
Risks of testosterone treatment
Benign prostatic hypertrophy
Prostatic cancer
Erythropoiesis
- Increased RBC/ haemocrit
Changes in GH-IGF-1 axis with age
Decrease in GH and IGF-1
GH treatment
- Effects on body composition
Increases lean body mass [2kg]
Decreases fat mass [2kg]
Still not functional benefits.
No change for bone density or lipids
Risks and side effects of GH therapy
Risks:
Cancers- Breast, colon, prostate
- T2 DM
Side effects:
- Soft tissue oedema
- Arthralgia
- Carpel tunnel
Changes of cortisol levels and age.
Trough and average cortisol levels rise
Earlier time for trough and peak
Mechanism behind increased cortisol levels with age?
Sapolsky’s glucocorticoid cascade hypothesis
- Decrease in hippocampal glucocorticoid and mineralocorticoid receptors [less negative feeback]
Affects hippocampal neurones= increase vulnerability to damage
- Decline in functions associated with hippocampus [memory, learning]
DHEAS and age
Declines.
- 5-10% of peak by 70-80
Not as important and as potent as androgens from testes in men
Non-specific marker
- Associations may not be causal [etc with cancer, T2 DM, CVD]
Thyroid function and age
- TSH
- T4, T3
Become slightly hypothyroid with age:
Slight TSH increase
Decreased peripheral conversion of T4 into T3.
= Decreased T3
Potential harms of T4 therapy
Osteoporosis
A Fib
Atherosclerotic coronaries
Effects of starvation
- Insulin
- Glucose
- Leptin
Decrease insulin
- Increased insulin sensitivity= decreased glucose.
Decreased levels of leptin
- Inhibits satiety, triggers starvation.
Leptin and starvation
Levels decrease to signal starvation
- Due to low body fat
Increases food intake and decreases energy expenditure
Decreases fertility
Starvation and androgens
Decreases fertility so
- Decreases FSH, LH, oestrogen, testosterone.
Amenorrhoea
Oestoporosis
Leptin and reproduction
When used to treat obesity, also:
- Increases gonadotrophin secretion
- Improvement reproductive organ maturation
- Induce puberty and fertility
Kisspeptin
Peptide that promotes release of GnRH from hypothalamus
- Especially at puberty
Can be inhibited or stimulated by oestrogen.
Reproduction and puberty modulated by leptin levels
- Leptin triggers stimulates
- So starvation inhibits Kisspeptin action
Starvation and GH
GH increased= GH resistance
- Decrease in IGF-1
Reversed with re-feeding
Starvation and cortisol
Increased levels
Many peaks
Starvation and thyroid function
Becomes hypothyroid
- Lowers basal metabolic rate to conserve energy
TSH and T4 low
Decreased T4 conversion to FT3
Increased T4 conversion to RT3
