MASTER METABOLISM: The reversal of greying has been reported in some hypothyroid patients, and thyroid hormone accelerates hair regrowth in rodents.

Hypothyroidism doubles noradrenaline, the stress hormone that causes greying and hair loss.

The reversal of greying has been reported in some hypothyroid patients, and thyroid hormone accelerates hair regrowth in rodents.

“A 63-year-old man, who and been progressively graying… https://t.co/F7fIFslVSP pic.twitter.com/mKIObKRRWX

— Master Metabolism (@lowmegatron) June 24, 2026

Hypothyroidism doubles noradrenaline, the stress hormone that causes greying and hair loss. The reversal of greying has been reported in some hypothyroid patients, and thyroid hormone accelerates hair regrowth in rodents.

“A 63-year-old man, who and been progressively graying over the years... was admitted to the intensive care unit (ICU) for 10 days, where he received support measures and intravenous therapy with 0.5 mg of L-thyroxine (precursor to thyroid hormone)... He was able to return home after a month. On discharge from the ICU, complete repigmentation of all gray hairs of his scalp was observed and these have retained their coloration during 2 years of follow-up. The patient did not receive any other medication while he was in hospital.” “These data suggest that follicles in the telogen phase can be induced to enter the anagen phase by the topical application of T3. In the in vitro experiments, T3 stimulated hair shaft growth.”

“Anecdotal case reports and a recent pilot study suggest that psychological stress and other behavioral factors accelerate the hair greying process (Nahm et al., 2013; Peters et al., 2017), a notion supported by studies in mice demonstrating that adrenergic stimulation by norepinephrine signaling leads to melanocyte stem cell depletion in mice (Zhang et al., 2020). However, contrary to mice where this process appears to be irreversible at the single hair follicle level, our data demonstrates that human hair greying is, at least under some circumstances, reversible.” “Upon fasting, adrenal glands produce hormones, cortisol and epinephrine, which then cause lipolysis to release free fatty acids. The release of these free fatty acids near the hair follicles causes apoptosis of HFSC and subsequently blocks hair growth.”

The research does suggest that you have to catch greying early if you are to reverse it...

References: The Role of Thyroid Hormone in Blood Pressure Homeostasis: Evidence from Short-Term Hypothyroidism in Humans.

Repigmentation of Gray Hair After Thyroid Hormone Treatment.

Quantitative mapping of human hair greying and reversal in relation to life stress. Hangry hairs: intermittent fasting linked to hair loss. 

Intermittent fasting triggers interorgan communication to suppress hair follicle regeneration.