Measuring testosterone in women and men

Area of Science:

• Endocrinology
• Clinical Chemistry
• Reproductive Medicine

Background:

• Serum testosterone (T) measurement is vital for diagnosing male hypogonadism and female androgen excess.
• Existing immunoassays exhibit significant variability, particularly at low concentrations in men and across all ranges in women.
• Factors like circadian rhythms, daily variations, stressors, and the menstrual cycle impact T levels, complicating accurate assessment.

Purpose of the Study:

• To highlight the challenges and variability in current serum testosterone measurements.
• To recommend standardized protocols for accurate T level assessment in men and women.
• To discuss the limitations of immunoassays and the role of mass spectrometry and free testosterone surrogates.

Main Methods:

• Review of factors affecting testosterone measurement accuracy.
• Analysis of limitations in current immunoassay techniques for testosterone.
• Discussion of mass spectrometry as a gold standard and the utility of calculated free testosterone surrogates.
• Emphasis on optimized sample collection (fasting morning for men, follicular phase for women).

Main Results:

• Immunoassays often fail to accurately measure testosterone at the lower end of the normal range for men and across the entire range for women.
• There is no universally accepted lower testosterone threshold for healthy adult men.
• Most free testosterone assays are unreliable, making calculated surrogates preferable.
• Standardized collection protocols and quality controls are essential for harmonizing commercial assays.

Conclusions:

• Accurate testosterone measurement requires standardized protocols, including specific timing for sample collection.
• Mass spectrometry offers superior accuracy but is not widely accessible; improved immunoassay harmonization and reliable free testosterone surrogates are needed.
• Collaborative efforts focusing on quality control and reference methods are crucial for improving the reliability of commercial testosterone assays.