Hypothyroidism

Hypothyroidism - A clinical state due to underproduction of thyroid hormones .PRIMARY HYPO-THYROIDISM( > 95 % )TSH highT3 low or normalT4 low. Problem is in the gland - ie gland failure due to♦ damage♦ inhibition♦ removal of gland itself. Iodine deficiency- worldwide commonest cause. Autoimmune thyroiditis- most common cause- Hashimoto thyroiditis Atrophic thyroiditis ( Primary Myxoedema ) May happen with or without goitre Atrophic autoimmune thyroiditis . Post-ablative therapy or surgery- Thyroidoectomy Radioactive Iodine External radiotherapy. drugs - Anti-thyroid drugs- about 15 % people will develop hypothyroidism 10-20 yrs after treatment♦ Carbimazole♦ Propylthiouracil Amiodarone Lithium Interferons Thalidomide Rifampicin. Transient thyroiditis- Subacute thyroiditis ( de Quervain's ) Postpartum thyroiditis- within 6/12 post partum. Infiltration Thyroid hypoplasia /agenesis - Tumour , amyloidosis , sarcoidosis , haemochromatosis , TB and scleroderma. Congenital -Absence or underdevelopment of the thyroid gland , ectopic hypoplastic gland or enzyme defect

Overt-TSH above normal reference range♦ usually above 10♦ FT4 is below the normal reference range May not be symptomatic In Pregnancy- TSH > 10 is overt hypothyroidism regardless of T4

Subclinical- Raised TSH but FT4 and FT3 normal Clinical features of hypothyroidism usually absent , but if present -related to degree of TSH elevation TPO antibodies help...