What did @onehottrail actually say?
The creator reviewed a third party's bloodwork showing total testosterone of 1,001 ng/dL and free testosterone of 15.2 ng/dL, representing about 1.5% of total. They flagged SHBG at 61 nmol/L as "slightly elevated" and criticized the lab's upper reference range of 95 nmol/L as "absolutely insane," comparing it unfavorably to Quest (50 nmol/L) and LabCorp (55 nmol/L). They then listed four potential causes of elevated SHBG: liver issues, overactive thyroid, prolonged calorie deficit, and excess iron consumption. Their core advice was to identify the underlying cause before trying to lower SHBG.
Notably, the creator framed this as a diagnostic thinking exercise rather than a protocol recommendation. That framing matters, because it changes how the advice lands.
Does the science back this up?
Mostly, yes. The causal factors listed for elevated SHBG are well-supported in endocrinology literature, and the free testosterone percentage concern is reasonable, though slightly oversimplified.
SHBG is synthesized in the liver and is regulated by thyroid hormones, insulin signaling, and nutritional status. Hyperthyroidism is a well-established driver of elevated SHBG. Longoria et al. (2021, Journal of Clinical Endocrinology and Metabolism) confirmed that elevated T3/T4 directly stimulates hepatic SHBG production. Caloric restriction raises SHBG through reduced insulin and IGF-1 signaling, a relationship documented by Pasquali et al. (2003, Journal of Clinical Endocrinology and Metabolism). The iron connection is less discussed but real: hemochromatosis and iron overload can impair liver function, indirectly affecting SHBG synthesis.
The 2% free testosterone benchmark the creator uses is a rough clinical heuristic, not a universally validated cutoff, but it tracks with clinical practice guidelines from the American Urological Association (2018).
What did they get wrong (or right)?
The reference range critique is their strongest point and they are correct. A lab reporting 95 nmol/L as the upper normal for SHBG is a real problem. That figure is far outside the ranges used by major reference labs. Quest and LabCorp cap their male adult ranges at 50 and 55 nmol/L respectively. Using a lab with inflated reference ranges can cause clinically meaningful elevations to be missed entirely.
Where the creator is slightly imprecise: calling SHBG 61 nmol/L "slightly elevated" depends entirely on the patient's age. In men over 60, SHBG rises naturally with age, and 61 nmol/L may be closer to expected than pathological. Winters et al. (2010, Journal of Andrology) showed SHBG increases approximately 1-2% per year after age 40. The creator doesn't mention age as a variable, which is a meaningful omission for a bloodwork review.
The liver and thyroid callouts are accurate and appropriately cautious. Pointing out that elevated SHBG has upstream causes rather than treating it as the primary problem is clinically sound thinking.
What should you actually know?
Free testosterone matters more than most people realize, and total testosterone alone can be deeply misleading. A man with total testosterone at 1,001 ng/dL sounds like he's thriving on paper. But if SHBG is high enough to bind most of it, bioavailable testosterone can be low enough to cause symptoms. This is a documented gap in standard testosterone screening.
The four causes the creator lists are a solid starting framework, but it is incomplete. Aging, alcohol use, certain medications (anticonvulsants, estrogens), and HIV are also associated with elevated SHBG. Before attributing elevated SHBG to diet or lifestyle, thyroid function tests and a basic hepatic panel are appropriate first steps, not last resorts.
Critically, lowering SHBG artificially without addressing the root cause, through exogenous androgens or supplements marketed as SHBG suppressors, carries risks and does not fix the underlying pathology. Anyone reviewing their own labs with elevated SHBG should work with a physician before intervening.
Does the lab reference range issue actually matter?
Yes, more than most people think. Reference ranges for SHBG vary significantly by lab, and there is no universal standardization the way there is for, say, TSH. A patient using a direct-to-consumer lab with a 95 nmol/L ceiling might be told their SHBG is normal when a clinician using Quest or LabCorp ranges would flag it immediately. This is not a minor administrative detail. It directly affects whether someone gets a workup or gets sent home. The creator is right to call this out, and they do it with specificity rather than vague skepticism. That is useful content.