Does the time of day matter when drawing labs for testosterone levels in a Polycystic Ovary Syndrome (PCOS) workup?

From the Guidelines

The time of day does matter when drawing labs for testosterone levels in a PCOS workup, with morning measurements, preferably before 10 AM, being ideal for assessing testosterone status. This recommendation is based on the natural diurnal variation in testosterone secretion, which is typically highest in the early morning and declines throughout the day 1. For PCOS evaluation, total testosterone and free testosterone are the most useful measurements, and these should be drawn in the fasting state if possible. The use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for androgen measurement is recommended due to its high accuracy, especially for measuring total testosterone, free testosterone, and other androgens like androstenedione and dehydroepiandrosterone sulfate 1.

Some key points to consider in the workup of PCOS include:

• The importance of consistent timing of blood draws to standardize results and improve diagnostic accuracy
• The consideration of repeat morning measurements if initial results are borderline or if there's strong clinical suspicion of PCOS despite normal initial results
• The potential for other androgens, such as androstenedione and dehydroepiandrosterone sulfate, to be measured if total testosterone and free testosterone are not elevated, although their specificity may be poorer 1
• The need for future studies to establish optimal normative cut-off values for androgen measurements in large, unselected, and ethnically diverse cohorts of women 1.

Overall, the goal is to provide an accurate diagnosis and effective management of PCOS, with consideration of the timing of lab draws being an important aspect of this process.

From the Research

Testosterone Levels in PCOS Workup

• The time of day for drawing labs for testosterone levels in a Polycystic Ovary Syndrome (PCOS) workup is not explicitly mentioned in the provided studies 2, 3, 4, 5, 6.
• However, it is known that testosterone levels can fluctuate throughout the day, with peak levels typically occurring in the early morning 4.
• The studies provided focus on the diagnosis and treatment of PCOS, as well as the role of testosterone in the condition, but do not specifically address the issue of timing for lab draws.
• One study notes that hormone measurements, including testosterone, should be taken in the early follicular phase of the cycle for accurate diagnosis 4.
• Another study discusses the importance of precise definition of normal ranges for hormones, including testosterone, in order to accurately diagnose PCOS 4.

Diagnostic Performance of Testosterone Immunoassays

• A study comparing the diagnostic performance of three testosterone immunoassays in PCOS patients found that testosterone levels measured on one assay showed superior discriminatory performance to the other two assays 3.
• The study suggests that calculated parameters, such as free testosterone and free androgen index, can improve the performance of testosterone immunoassays in diagnosing PCOS 3.
• Another study found that total testosterone concentration was the most frequently abnormal biochemical marker for PCOS, and that testosterone, androstenedione, or LH, either alone or in combination, were raised in 86% of women with PCOS 4.

Testosterone to Dihydrotestosterone Ratio

• A study investigating the role of the testosterone to dihydrotestosterone ratio in PCOS patients found that this ratio was significantly higher in PCOS patients compared to healthy controls 5.
• The study suggests that this ratio may be a new biomarker for an adverse metabolic phenotype in PCOS patients, and that it is correlated with various adverse anthropometric, hormonal, lipid, and liver parameters, as well as parameters of glucose metabolism 5.