it cause hair loss trough this diferent mechanism
1/ it acts as an aromatase inhibitor, aromatase is the enzime that transform testosterone , androstendione and dheas into estrogen, estrogen as is well know protect hair from falling it makes the anagen phase longer .As the aromatase pathway is blocked by metformin, then there is more substrate or free androgens to be converted in DHt , trough 5 alpha reductase, they are converted then to dht the most androgenic male hormone, that is the direct cause of androgenic alopecia.as an example women with breast cancer than take aromatase inhitors loose their hair very fast, in a male type pattern.this mechanism cause permanent hair lost,Actually because it cause aromatase inhibition they are testing it as breast cancer coadjuvant treatment,
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2/the second mechanism it cause hair loss is by increasing dheas levels as it caused a mild suprarenal impairment, so the adrenal gland produce more androgens to compensate.dheas is a weak androgen but it can be converted trough the enzime 5 alpha reductase into a very potent androgen dht, that as above mentioned cause hair loss.the hair lost trough this mechanism, is permanent
3/the 3 mechanism metformin cause hair thining is trough decreasing the igf1 effect on the body, igf1 is a metabolic part that caused most of the growth hormone effects it caūse hair to grow stronger and thicker, people who have low igf1 levels has very thin hair.this mechanism is temporal, once you stop taking metformin your hair will grow strong again,but your sugar will raise againActually as it decrease igf1 levels they are testing it as a cancer treatment.
4/the 4 mechanism is trough inhibiting B12 absortion , b12 deficiency cause hair loss.this is also a temporal mechanism