Testosterone

Background

  •  Presentation
    • Loss of morning erections, erectile dysfunction
    • Decreased libido
    • Lethargy, low mood, irritability
  • Diurnal variation of levels – testosterone should be measured as early morning sample and repeated 6 weeks after first test
  • Causes
    • Primary hypogonadism (failure of testes to produce testosterone)
      • Ageing
      • Undescended testes
      • Mumps orchitis
      • Testicular trauma
      • Klinefelter syndrome
    • Secondary hypogonadism (lack of pituitary signal – low LH)
      • Medications – opiates, glucocorticoids
      • Pituitary disease – adenomas, hyperprolactinaemia
      • Kallmann’s syndrome
      • Haemochromatosis
      • Hypothalamic disorders e.g. sarcoidosis, histiocytosis

 

Clinical management

  • Investigation
    • Morning testosterone, LH, FSH, oestradiol, prolactin, FBC, U+E, LFTs, HbA1c, PSA (if > 40yo)
  • When to treat
    • < 8 nmol/L – treat
    • 8-12 nmol/L – offer treatment if the calculated free testosterone level is < 0.225nmol/l and there are symptoms
    • > 12 nmol/L – does not need replacement
    • Treatment in patients with classical hypogonadism is effective and safe and usually long term
    • Treatment for patients with few symptoms – trial for 6 months can be commenced but should be stopped if no symptomatic benefit
  • Testoterone therapy contraindications
    • Prostate cancer
    • Severe LUTS
    • Haematocrit > 50%
    • Untreated severe sleep apnoea
    • Untreated severe heart failure
    • Liver cancer
    • Serious liver or kidney disease
    • Breast cancer
    • Fertility considerations
  • Treatment
    • Before starting treatment
      • Check for prostatic symptoms
      • Measure PSA
      • Perform PR
      • Measure FBC – testosterone can cause polycythaemia – Hct > 53% requires prompt haematological review
    • Target
      • testosterone level 15-18 nmol/l
    • Formulations
      • Testogel (1% gel) – 5g (50mg) OD in the mornings (titrate up to 10g in 2.5g steps)
      • Tostran (2% gel) – max 4g (80mg)
      • Nebido (IM injection) – injected every 10-14 weeks – needs deep IM injection and there is risk of pulmonary oil microembolism – cough/SOB/sweats/chest pain/lightheadedness
  • Monitoring
    • Bloods – FBC, lipids, PSA, testosterone
    • PSA – a rise should be monitored carefully (even within normal range)
    • DEXA – if bone density is low
    • Check testosterone 6-12 hours post gel application or 2 weeks prior to next Nebido depot
  • Length of treatment
    • Can be used long term if beneficial and being monitored annually