You all got me curious enough to dig up the mechanisms for hair loss. Go ahead, roll your eyes and groan because this may be WTMI for most people.
As with most medical conditions the MD's will not speculate as to the cause of alopecia areata "spot balding hair loss".. it is unknown. They do have suspicions and have detected three main reason why. First, it is known that the autoimmune system plays a role.
Hello Hashimoto's and Graves sufferers.. AI sucks!) It is hypothesized that the affected hair follicles are attacked by a person's own immune system (white blood cells), resulting in the cessation of hair growth in patchy areas. When all of the hair in this patch enters this resting phase at once due to WBC attack, the hairs all slough off shortly after, creating a bald patch.
In addition to the AI attack and destroy hair loss hypothesis, many hormone swings, medications or diseases can change phase duration for hair retention and shedding and thus accelerate hair loss or cause more than a normal amount of the hair to be in synchronous growth and then slough. For example, estrogens
(Hello Ladies! Estrogen.. our thyroid regulates this bugger too!) during pregnancy are known to prolong the anagen growth phase and when pregnancy is over, a large number of hairs go into the telogen resting phase. As expected, 6 weeks to 6 months after birth large amounts of hair break or slough giving the impression that one's hair is falling out.
Women are so lucky! So does pregnancy fall into the disease or hormone swing category? Actually hairs gradually go back to their random pattern of growth and rest and the "hair loss" problem subsides as the hair growth cycle is reset due to hormone reset.
Third medication and disease induced hair loss:
Drugs that can cause temporary hair loss include cancer treatment chemotherapeutic agents, some anticoagulants (blood thinners), excessive vitamin A intake, vitamin A derivitives such as Accutane or Retin A used to treat acne and skin problems, and beta-adrenergic blockers
(hyper patients get thumped with these often and frequently) used to control blood pressure such as Inderal, Lopressor. Some antidepressant and antianxiety drugs can also cause hair loss.
Another tidbit of info on beta-blockers.. abrupt cessation of a beta-blocker can and is well known to induce a thyroid storm. Just learned this one and my cardiologist is recommending one for me and trying to decide on the right one.
Whee!
So in summary why do thyroid dysfunctional individuals lose hair? It is totally unfair.. but the thyroid is the overseer of our bodies hormones and metabolic regulation processes.. so when it is low it can not tell your body to produce and grow and metabolize all that needs to be done and focuses instead on essential systems.. like heart, lungs, brain.. etc.. hair and skin are nice.. but in the long scheme of things your body knows they can be sacrificed.. as well as it knows if you can not support all of your own systems that period and fertility should be put on hold.. because you do not have enough thyroid hormone for your self much less for a bun in the oven. It is sad.. and sucks.. but if we can get medicated and balanced.. things will sit well once more. On paper did mention dramatic shifts in hormone presence could stimulate and rest hair growth states.. this might explain what goes on during level adjust of our thyroid meds.. when you finally get enough T4 and T3 to reboot your estrogen and certain hormone systems.. initial flood of hormones may cause a resting growth state to occur in ones hair and a massive shedding and rerandomization of hair growth to commence. Once again this is only hypothesized information.. but it make sense to me.
In addition to whatever treatment a doctor can give you for the hari loss, many have found luck with essential oil therapy. Rubbing on the scalp is known to stimulate hair growth certain oils are thought to add nutrients and aide in the patchy areas regrowth.
Hair fertilizer? Who would have thunk it. One study showed almost a 50% improvement in women with hair loss who used a daily mixture of thyme, rosemary, lavender, and cedarwood essential oils in a mixture of carrier oils (jojoba and grapeseed) and massaged it into their scalps. Seems like it would smell good and it shouldn't hurt.. so I am passing this tidbit along as well.
Well this concludes the running hypothesis of the mechanisms of hair loss.

Sincerely,
MG