What is the normal range of testosterone levels in females?

Normal Testosterone Levels in Females

In healthy premenopausal women with normal menstrual cycles, total testosterone levels typically range from 15-46 ng/dL, with free testosterone ranging from 1.2-6.4 pg/mL. 1

Reference Ranges for Reproductive-Age Women

Total Testosterone

• Normal range: 15-46 ng/dL (5th to 95th percentile for a typical 30-year-old woman) 1
• Women with no clinical signs of hyperandrogenism (no acne, hirsutism, or menstrual dysfunction) have mean testosterone levels of 14.1 ng/dL 2
• The upper limit of normal is approximately 28 ng/dL (mean + 2 standard deviations), which provides 84% sensitivity for detecting hyperandrogenemia 2

Free Testosterone

• Normal range: 1.2-6.4 pg/mL (5th to 95th percentile) 1
• Calculated free testosterone: 1.3-5.6 pg/mL 1

Bioavailable Testosterone

• Normal range: 1.12-7.62 ng/dL 1

Critical Clinical Considerations

Age-Related Changes

• Testosterone levels exhibit an age-related decline in premenopausal women, while sex hormone-binding globulin (SHBG) remains relatively stable 1
• SHBG normal range: 18-86 nmol/L 1

Menstrual Cycle Variations

• Testosterone shows a small mid-cycle increase, but this variation is minor compared to overall variability 1
• These reference ranges can be applied regardless of menstrual cycle day when the sample is taken 1

Clinical Thresholds for Hyperandrogenism

• Women with menstrual dysfunction alone (no acne or hirsutism) have mean testosterone of 17.9 ng/dL 2
• Women with mild hirsutism show testosterone levels of 38.4 ng/dL 2
• Women with moderate to severe hirsutism demonstrate testosterone levels of 49.0 ng/dL 2

Major Pitfall: Commercial Laboratory Reference Ranges

The most critical error in clinical practice is relying on commercial laboratory reference ranges, which are often inappropriately wide and fail to detect hyperandrogenemia in affected women. 2

Why Commercial Labs Fail

• Commercial laboratories typically report upper limits around 95 ng/dL, which is more than 3 times higher than the clinically relevant threshold 2
• This makes detection of hyperandrogenemia essentially impossible when using standard commercial ranges 2
• Most hyperandrogenic women have testosterone levels that fall within these inappropriately wide "normal" ranges, leading to missed diagnoses 2

Laboratory Variability Issues

• There is wide variability in laboratory reference values, with low reference values ranging from 130-450 ng/dL (a 350% difference) across different labs 3
• Different assays and methods contribute to this inconsistency 3
• Reference values are typically established using statistical models without clinical considerations 3

Measurement Recommendations

Optimal Testing Conditions

• Collect morning blood samples for most accurate assessment 1
• Use validated immunoassays or LC-MS/MS methods for accurate quantification, particularly in the lower concentration ranges typical of females 4
• Standard immunoassays often lack accuracy below 100 ng/dL, which encompasses the entire female physiological range 4

When to Suspect Hyperandrogenism

• Any woman with testosterone above 28 ng/dL warrants evaluation for hyperandrogenism 2
• Clinical signs (hirsutism, acne, menstrual dysfunction) should prompt testing even if levels fall within commercial laboratory "normal" ranges 2