ICL 4.3: Andropause Flashcards
is there a true andropause?
no not really, there isn’t a measurable/observable event like menopause
it’s just a normal decline in testosterone production after the 5th decade that’s usually associated with a rise in LHindiating end organ unresponsiveness
ADAM, LOH, AD, TD are all also terms for andropause
what is testosterone deficiency syndrome?
declining testosterone levels after age 40 yrs
symptoms: diminished sense of well being, libido, fatigue, ED.
what are the complications associated with testosterone deficiency syndrome?
- metabolic syndrome
- sarcopenia
- decreased bone density
what is hypogonadism? how is it different than testosterone deficiency?
male hypogonadism is defined by the Endocrine Society as “a clinical syndrome that results from failure of the testis to produce physiological levels of testosterone (T) AND sperm due to disruption of one or more levels of the hypothalamic-pituitary-testicular axis.”
in routine urologic practice the term “Testosterone Deficiency” may be used to refer specifically to the syndrome of low serum testosterone without regard to spermatogenic potential so that’s why testosterone deficiency is
what is the prevalence of testosterone deficiency?
eh we don’t know, 2-77%
variability due to cut off used, assay used, heterogeneity, total vs free T
variability due to cut off used, assay used, heterogeneity, total vs free T – lots of inter and intra lab variability of levels
there’s no clear data to show what thresholds to use to define levels below which deficiency symptoms are observed and above which therapeutic benefits occur –> so don’t treat the number, treat the patient!
what is generally accepted cut off for testosterone deficiency?
less than 280-300 ng/dL
why has testosterone testing and prescriptions have nearly tripled in recent years?
- direct-to-consumer advertising
- clinical centers for men’s health not run by MDs
- anti-aging industry
many patients were started on TRT with no clear indications, no prior levels drawn, no follow up levels
there are also many men who could have potentially befitted from treatment – did not get TRT due to unresolved concerns with prostate cancer, heart disease, CVE
which cells make testosterone?
Leydig cells in the interstitum between the seminiferous tubules –> they do this under stimulation from LH, in the interstitium of the testes
there’s also a minor fraction that comes from the adrenal glands
how do intratesticular vs. serum testosterone levels differ?
Intratesticular Testosterone is 500-1000 times higher than circulating T levels
if you start someone on exogenous T, their serum levels could be high but the intratesticular levels could be low due to the blood testicular barrier –> the problem is that because of the high serum levels, there will be down regulation of LH within the testicles which will cause even lower levels of testosterone production in the testicles
which proteins bind testosterone?
- pre-albumin
- sex hormone binding globulin (SHBG)
it is only the bioavailable testosterone(free + albumin bound) testosterone that is active in tissues –> so if SHBG is high, even though total testosterone might be high, the bioavailable T is low and they might have symptoms of testosterone deficiency
what does circulating testosterone do?
- circulating T is converted to Estradiol (E2) in adipose cells using enzyme aromatase.
- circulating T inhibits hypothalamic release of GnRH (gonadotropin releasing hormone).
- estradiol inhibits LH release from pituitary in response to GnRH
- T is converted to active form DHT (DiHydroTestosterone) by enzyme 5 alpha reductase in prostate, scalp etc.
what happens to SHBG levels with age?
SHBG increases with age and can make isolated T level check inaccurate in patients above age 65 yrs
so it’s really unreliable to measure free T levels in older people so you have to calculate the bioavailable testosterone levels by doing the total T and subtracting the SHBG to get the bioavailable T
what is the normal rhythm of testosterone?
it has a normal, circadian, seasonal rhythm
there’s a seasonal drop in the spring
in the morning, daily T rises and there’s a peak from 8-11 AM and at noon it drops so always get morning T levels
there are also hourly pulses in T based on stress, excitement, etc. but this pulsitility blunts out after 50
what are the types of hypogonadism?
- hypergonadotrophic hypogonadism
2. hypogonadotrophic hypogonadism
what is hypergonadotrophic hypogonadism?
high LH
with or without high FSH
low T
tells you that the end organ isn’t responding well!
can be congenital and acquired
acquired due to aging -> TDS focus of this lecture