You noticed the shift. Desire that used to run in the background now needs a running start, especially after a hard travel week or a stretch of short sleep. The easy story is "my testosterone dropped, put me on T, problem solved." It is a tidy story. It is also usually incomplete.
Libido is not a single dial. It is a system with several inputs, and testosterone is only one of them. Before an independent provider concludes that low testosterone is the driver, the Velri clinical review process looks at a wider panel: prolactin, sex hormone binding globulin (SHBG), thyroid function, and glucose. Here is why each one matters, and why skipping them can leave you optimizing the wrong variable.
Testosterone is real, but "total T" can mislead
When a lab reports "testosterone," it usually means total testosterone: everything circulating, bound and unbound. But most of that is bound to carrier proteins and biologically unavailable. The fraction that actually reaches tissue is free (and loosely bound) testosterone [1]. Two men can share an identical total number and have very different free testosterone, because the carrier proteins differ.
That is why the Endocrine Society recommends diagnosing low testosterone using symptoms plus repeated, morning total testosterone measurements, with free testosterone considered in specific situations, rather than a single snapshot [1]. Testosterone follows a daily rhythm and dips later in the day, so an afternoon draw after a red-eye can read low for reasons that have nothing to do with a durable deficiency [1].
Translation: a low number on one convenient test is a starting question, not a conclusion.
Source: [1] Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline
SHBG: the protein that decides how much T you actually use
Sex hormone binding globulin is the main carrier protein for testosterone. When SHBG rises, more testosterone gets locked up and less is free to act; when SHBG falls, the free fraction shifts the other way [2]. SHBG is not static. It tends to rise with age, with thyroid overactivity, and with certain liver conditions, and it tends to fall with insulin resistance, obesity, and hypothyroidism [2][3].
This is the marker high-performers most often overlook. A disciplined 53-year-old with rising SHBG can have a "normal-ish" total testosterone and a genuinely low free fraction. Add testosterone without understanding SHBG and you may be treating the symptom while missing the mechanism. Measuring SHBG lets a provider calculate or interpret free testosterone in context, which is exactly the kind of detail an optimizer wants engaged rather than glossed over.
SHBG direction · marker = More SHBG = less free T
Source: [2] Sex Hormone-Binding Globulin (SHBG) as an Early Biomarker (StatPearls / NIH Bookshelf)
Prolactin: the quiet lever that suppresses desire
Prolactin is best known for lactation, but elevated prolactin in men is a recognized cause of reduced libido and erectile difficulty, and it can lower testosterone by suppressing the signals from the brain that tell the testes to produce it [4]. Causes range from common and benign (stress, certain medications) to clinically important (a prolactin-secreting pituitary adenoma) [4].
This is why prolactin belongs on the panel and why a T prescription without it can miss something meaningful. If prolactin is the driver, more testosterone does not address the underlying problem, and it can delay finding a cause that has its own management path. Checking prolactin is not over-testing. It is ruling out a specific, treatable explanation before anyone reaches for a hormone.
Thyroid: the metabolic thermostat behind low energy and low drive
Thyroid hormone sets the pace for much of your metabolism, and both underactive and overactive thyroid can blunt sexual desire and function [5]. Hypothyroidism in particular overlaps heavily with the exact symptoms men attribute to low T: fatigue, low mood, sluggish recovery, reduced libido [5]. It also pushes SHBG down, which tangles the testosterone picture further [2][3].
A thyroid stimulating hormone (TSH) test is inexpensive and high-yield. If a sluggish thyroid is contributing, addressing it may resolve symptoms that testosterone would only have masked. For the man who runs marathons and lifts five days a week and still feels his edge dulling, thyroid is a marker worth ruling in or out before assuming the answer is androgens.
Glucose and insulin resistance: the upstream driver
Metabolic health sits underneath all of this. Insulin resistance and type 2 diabetes are strongly associated with both lower testosterone and erectile dysfunction, and the relationship runs in more than one direction [6][7]. Higher insulin tends to lower SHBG, which changes the free-testosterone math again, and vascular changes from high glucose directly affect erectile function independent of hormones [6][7].
The American Diabetes Association notes that erectile dysfunction is common in men with diabetes and is often an early sign of vascular trouble [7]. So a fasting glucose or A1c is not a detour. For the exec whose performance has become inconsistent and unpredictable, ruling out a metabolic contributor may matter more than any hormone level, and it may point to changes that help the whole system rather than one symptom.
Why the panel beats the shortcut
None of this means testosterone is irrelevant. It means desire is multi-causal, and the responsible move is to read the full picture before assigning blame. A provider who checks total and free testosterone, SHBG, prolactin, thyroid, and glucose is not being slow. They are avoiding the classic error of treating a number in isolation.
For the optimizer, this is the depth you were looking for: a protocol that starts from mechanism, not from a single lab flag. For the man whose confidence is taking the hits, it is the difference between chasing symptoms and understanding causes. A prescription is never guaranteed, and if any medication is appropriate, that decision rests with an independent licensed provider who has reviewed your labs and history.
This article is educational and is not medical advice. Talk with a licensed provider about your specific situation.
Source: [1] Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline, [2] Sex Hormone-Binding Globulin (SHBG) as an Early Biomarker (StatPearls / NIH Bookshelf), [4] Hyperprolactinemia and male reproductive function (StatPearls / NIH Bookshelf), [5] Thyroid dysfunction and sexual function in men, [7] American Diabetes Association: Sexual health and diabetes (erectile dysfunction)
Where Velri fits
Velri is a technology and coordination company, not a medical practice. Velri helps coordinate the parts so you can manage the process from your phone: lab work to build the marker picture described above, a visit with an independent, physician-led Provider Group that reviews your results and history, and, if a provider determines it is appropriate, fulfillment through an independent, licensed pharmacy. Velri does not provide medical care and does not decide who receives treatment.
Where a provider considers compounded medications, note this: compounded medications are not reviewed or approved by the FDA for safety, effectiveness, or quality. Compounded products are not equivalent to or interchangeable with any FDA-approved brand-name drug. Availability varies by state. Velri coverage starts in Nevada, with more states rolling out over time.
