Testosterone reference range

Covers what “normal” testosterone ranges mean on lab reports, why reference intervals vary by age, lab, and testing method, and how to interpret total vs free testosterone. Helps men understand when a result is truly low and what follow-up labs and lifestyle or TRT discussions may be appropriate.

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Got “Normal” testosterone on Function Health but still feel off? How to interpret results and plan next steps.

Got “Normal” testosterone on Function Health but still feel off? How to interpret results and plan next steps.

Dr. Susan Carter, MD avatar
Dr. Susan Carter, MD: Endocrinologist & Longevity Expert
Feb 09, 2026 · 11 min read

A testosterone result can be “normal” and still feel off because testosterone deficiency is diagnosed by symptoms plus consistently low morning total testosterone on repeat testing (often around ~300 ng/dL), and total testosterone can look adequate while free testosterone is low when SHBG is elevated. Here’s how to decide when a repeat draw matters, which ...

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