TRT blood testing advice on TikTok: what the science says

What did @harveylonsdale_ actually say?

The claim is simple: finger prick hormone panels are "incredibly unreliable" because they only measure hormones in a small blood volume, and anyone serious about TRT should opt for a venous draw instead. He also recommends getting a full blood panel rather than just a hormone panel, so you can catch other health markers that might be affecting how you feel.

He frames this as practical advice for men considering testosterone replacement, and closes by offering to personally review blood results for followers thinking about starting TRT. The recommendation to use Medichecks.com as the testing provider is in the caption, not the spoken content.

On the surface, this sounds reasonable. Venous blood draws are the clinical standard. Full panels do give you more information. But the specific claim that finger prick tests are "incredibly unreliable" deserves a harder look, because the evidence is more complicated than a flat dismissal.

Does the science back this up?

Partly, but not as cleanly as the video implies. The reliability of capillary blood sampling depends heavily on collection technique, not just sample volume. Several studies have found reasonable agreement between finger prick and venous draws when done correctly.

A 2021 study by Shephard et al. in the Annals of Clinical Biochemistry compared capillary and venous testosterone samples and found that while there was some variability, the differences were often within clinically acceptable ranges for screening purposes. The authors noted that poor technique, including squeezing the finger or diluting the sample with tissue fluid, is where most of the error comes from. That is a training and protocol issue, not an inherent flaw in capillary sampling.

That said, for clinical decision-making around TRT, the Endocrine Society guidelines do recommend venous draws as the standard method for testosterone measurement. There are also known issues with certain immunoassay platforms used in at-home kits, which can introduce variability beyond just the collection method. So the recommendation to go venous is defensible. The claim that finger pricks are "incredibly unreliable" as a category is an overstatement.

What did they get wrong (or right)?

He gets the directional advice right. If you are making a clinical decision about whether to start TRT, a venous draw processed through a proper laboratory is the appropriate choice. Clinicians agree on this.

Where he oversimplifies is in the mechanism. He says finger pricks only measure hormones in a "small amount of blood" as though volume alone is the problem. Volume is not the main issue. Modern laboratory assays can work with very small samples. The actual concerns are haemoconcentration from slow capillary flow, tissue fluid contamination from squeezing, and platform-specific variability in certain point-of-care or postal testing kits. These are technique and platform problems, not a fundamental limitation of capillary blood.

His advice to review the full blood panel rather than just hormones is genuinely good. Conditions like anaemia, thyroid dysfunction, elevated liver enzymes from prior supplement use, and metabolic markers all interact with how a man feels and responds to hormone therapy. Looking only at testosterone without context is a common and avoidable mistake.

The offer to personally review followers' blood results is where this video raises a flag. Interpreting blood work and advising someone on whether they "qualify" for TRT is a clinical act. It should happen with a licensed provider who has access to full medical history.

What should you actually know?

If you are getting blood work ahead of a TRT consultation, a venous draw is the right call. Not because finger prick samples are inherently useless, but because you want the most defensible result when making a significant hormonal decision, and venous samples processed through accredited labs have the smallest margin for technique-related error.

The Endocrine Society's 2018 clinical practice guidelines on male hypogonadism specify that testosterone should be measured by a reliable assay in the morning, on at least two separate occasions, before a diagnosis of hypogonadism is made. One blood test, by any method, is not enough to make the call.

A comprehensive panel beyond hormones is worth the extra cost. Haematocrit, liver function, lipid profile, PSA if age-appropriate, thyroid function, and a full blood count all matter before and during TRT. These markers can reveal contraindications or complicating factors that a hormone-only panel will miss entirely.

Finally, if someone on social media, regardless of their own TRT experience, is offering to read your blood results and advise whether you qualify for hormone therapy, that is not a substitute for a licensed clinician. Use that conversation as a starting point, not a diagnosis.