madman
Super Moderator
Future directions for harmonizing testosterone reference ranges in UK labs to minimize variation among clinicians and centers, making treatment thresholds more robust. Method-specific reference ranges using LC-MS/MS, like cortisol cut-offs in the cosyntropin test, may help, but resource limitations hinder implementation. The role of age-specific reference ranges and cut-off values for obese and non-obese men remains uncertain. Follow current guidance until more data is available.
Key take-home points:
Key take-home points:
- Total testosterone levels should be tested in men with symptoms of adult male hypogonadism using morning, fasting blood samples when not acutely ill
- Testosterone levels vary during the day, with higher levels in the morning and lower levels in the afternoon
- Nightshift workers have different testosterone patterns due to their sleep schedules
- Testosterone levels drop during acute illness, so testing is not recommended during that time
- A total testosterone value <8 nmol/L with suggestive symptoms indicates hypogonadism and may benefit from treatment
- Total testosterone >12 nmol/L is unlikely to represent hypogonadism, except in specific cases
- Calculated free testosterone is not diagnostically useful beyond total testosterone when SHBG is within the reference range
- Checking SHBG is recommended in men with conditions that may cause abnormal SHBG levels and in those with borderline total testosterone
- Direct measurement of free testosterone using equilibrium dialysis followed by MS is the recommended reference method
- This method is not available in routine clinical practice in the UK
- Other direct measurement methods are inaccurate and not recommended
