Due to ininsufficiency of thyroid hormone.
Clinical Features:
Contrast of thyrotoxicosis i.e.sensetivity to cold,dry hair,forgetfullness,puffyface,breadycardia,periorbital swelling,dull or idoictic face,large tongue,speech monotonus,and husky voice muscle cramps,tiredness Menorrhagea T3 +T4 decrease while TSH increase(in primary cases TSH normal or low).
Hair Loss in Hypothyroidism