Investigation in testosterone deficiency

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):

Open Image in Modal

• 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:

• Lunenfeld B, Mskhalaya G, Zitzmann M, et al. Recommendations on the diagnosis, treatment and monitoring of hypogonadism in men. Aging Male 2015;18:5-15.
• Dohle GH, Arver S, Bettochi C et al. Guidelines on Male Hypogonadism. European Association of Urology 2017. Available at: http://uroweb.org/guideline/male-hypogonadism/ (Accessed May 2018).
• Caronia LM, Dwyer AA, Hayden D, et al. Abrupt decrease in serum testosterone levels after an oral glucose load in men: implications for screening for hypogonadism. Clin Endocrinol (Oxf) 2013;78:291-296.
• Lehtihet M, Arver S, Bartuseviciene I, et al. S-testosterone decrease after a mixed meal in healthy men independent of SHBG and gonadotrophin levels. Andrologia 2012;44:405-410.
• British Society of Sexual Medicine. Guidelines on the management of sexual problems in men: the role of androgens 2010. Available at: http://bssmorguk.ipage.com/wpcontent/ uploads/2017/05/UK_Guidelines_Androgens_Male_2010.pdf (Accessed May 2018).