The Blood Tests Worth Asking For
The practical version, before the mechanisms
1 min read·Updated July 2026
If you want the practical version before the underlying science, this is it. Everything here is explained and cited properly in the sections that follow.
| Marker | What to know |
|---|---|
| Total testosterone | Men: roughly 300–1,000 ng/dL, optimal range debated. Women: roughly 15–70 ng/dL. Low levels linked to fatigue, low mood, and muscle loss. |
| Free testosterone | More clinically useful than total — measures what's actually available to tissues. Can be low even when total testosterone looks normal. |
| SHBG | Sex Hormone Binding Globulin — high SHBG reduces the free (usable) fraction of testosterone, so your total number can look normal while the usable amount is actually low. |
| Oestradiol (E2) | Relevant for both sexes. Too low: bone loss, dry skin, mood issues. Too high in men: gynaecomastia (breast tissue growth), water retention — often from excess aromatisation of testosterone. |
| DHEA-S | An adrenal precursor hormone to testosterone and oestrogen. Declines sharply and predictably with age. |
| Thyroid panel (TSH + Free T3/T4) | Thyroid dysfunction closely mimics general hormone imbalance — fatigue, weight change, mood shifts. Often missed on a basic panel that only checks TSH. |
| Prolactin | Elevated prolactin suppresses testosterone and libido in both sexes. Can be raised by chronic stress, certain medications, or, rarely, a pituitary issue. |
The one thing worth remembering
Ask for free testosterone and SHBG alongside total testosterone, and a full thyroid panel (not just TSH) — these three additions catch more genuine hormonal issues than any single number on a standard panel.