Hello, Hair loss can be from severe and prolonged hypothyroidism and hyperthyroidism. The loss is diffuse and involves the entire scalp rather than discrete areas. The hair appears uniformly sparse. Regrowth is usual with successful treatment of the thyroid disorder, though it will take several months and may be incomplete. It is unusual for mild (e.g. subclinical) hypothyroidism or hyperthyroidism, or short-lived thyroid problems to cause hair loss. Some forms of hypothyroidism and hyperthyroidism come on abruptly and are diagnosed early, while others may have been present for months or years before diagnosis. Hair loss due to thyroid disease becomes apparent several months after the onset of thyroid disease. This is due to the long hair cycle. In such cases, paradoxically the hair loss may follow the treatment for the thyroid and the thyroid medication may be erroneously blamed, leading to the withdrawal of treatment, which in turn may worsen the hair loss. Once you get your thyroid disease diagnosed and the right treatment is prescribed to regulate thyroid hormone levels, the hair loss problem should resolve itself. Healthy hormone levels mean healthy hair growth. It may take some time to find the right dosage of thyroid hormone to get your thyroid under control. After initiation of therapy, the patient should be reevaluated and serum TSH should be measured in 6 weeks and the dose adjusted accordingly. Symptom may begin to resolve after two to three weeks. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Heang Chan Raksmey, General & Family Physician