investigation in testosterone deficiency

Last edited 06/2018

Blood tests - measurement of morning basal testosterone, LH, FSH, PRL - measurement of the basal levels of testosterone, LH and FSH will allow distinction between gonadal disease and hypothalamic-pituitary disease (1)

  • primary hypogonadism - elevated gonadotrophin levels and low testosterone levels

  • secondary hypogonadism - low to normal gonadotrophin levels and low testosterone levels

When considering a diagnosis of symptomatic TD, other blood investigations should include:

  • haematocrit as part of FBC
  • prostate specific antigen (PSA), with appropriate counselling
  • Appropriate tests according to physical findings and to determine cardiovascular risk

Total testosterone (TT) should be measured before 11am (2,3) with a reliable method, on at least two separate occasions,(3) preferably 4 weeks apart. Fasting levels should be obtained where possible, (3)as non-fasting levels may be up to 30% lower (3)If TT is low or borderline (<12 nmol/L):

  • Measure sex hormone-binding globulin to calculate free testosterone (FT: an online FT calculator and downloadable app, sponsored by the Primary Care Testosterone Advisory Group, can be found at: http://www.pctag.uk/testosterone-calculator/)
  • Measure serum luteinising hormone (LH) to differentiate primary from secondary TD.
  • Measure follicle stimulating hormone (FSH) if fertility is an issue

Biopsy of the testes may be necessary for diagnosis but rarely reveals a treatable pathology.

Other investigations may be indicated and include:

  • skull radiology including a pituitary CT scan
  • semen analysis
  • chromosomal analysis e.g. Klinefelter's disease
  • bone age estimation

Asuggested algorithm for assessment of possible testosterone deficiency in primary care (1):

  • Key points (contributor: Professor Mike Kirby 5/6/2018):
    • an acute illness may cause a fall in testosterone levels, therefore investigate suspected testosterone deficiency once any acute illness has fully resolved

    • most discriminant symptoms associated with low testosterone (<12nmol/L) are: low libido, loss of early morning erections & erectile dysfunction - particularly in combination

    • consider potentially reversible factors that may be causing a low testosterone, that can be addressed - concurrent illness, certain drugs (prescribed or otherwise e.g. ketoconazole, cimetidine, spironolactone, chemotherapy, opioids) and lifestyle factors (e.g. excessive alcohol; stress; significant weight gain/obesity, excessive exercise etc.).

Reference:

 

Related pages:

testosterone deficiency (TD) in a man