Thyroid hormone by Dr. Anurag Yadav

Thyroid hormone,
structure of hormone,
synthesis of thyroid hormone,
mechanism of Thyroid hormone action,
Physiological effect of Hormone,
Disorders related with thyroid hormone,
drugs used in treatment for the thyroid disorders.

1. Thyroid Hormones Presenter : Dr Anurag Yadav

2. Secreted by the thyroid gland Gland secret major hormone; Thyroxine (T4) Triiodothyronine (T3) Controlled by the primarily TSH (Thyroid stimulating hormone) secreted by the ant Pituitary gland. Gland also secrete calcitonin (imp hormone in calcium metabolism).

3. Both T3 & T4 are bound to plasma proteins Thyroxine binding globin (TBG) Transthyretin (TTR – formerly known as Thyroxine binding prealbumin [TBPA]) Albumin T4 is secreted 20fold excess over T3. TBG carry 80% of bound hormone (T4>T3), 10% by albumin, 10% TTR

4. Approximately 99.98% T4 bound 99.7% T3 bound fT4 is higher conc than fT3. Unbound hormone is available for the biologically action/activity.

5. About 93% is secreted as thyroxine & 7% as T3. However eventually converted to T3 in tissue. T3 is 4 times potent than T4.

6. Iodine is required for the formation of thyroid (150-200 μ g/day) ( sr 5-10 μ g/dL) About 80% is stored in Thyroid gland. Ingredients which prevent the utilization of Iodine are called as Goitrogens .

7. Action mediated by TSH = cAMP (secondary messenger)mediated Thyroxine = intracellular receptor mediated

8. Assay of Hormone T3, T4, TSH, FT4, FT3,rT3, Anti-TPO, Anti- Tg Assay by ELISA/CLIA/ECLIA Normal reference interval T3 – 0.8-2.0ng/ml T4 – 5.1-14.1 μ g/dl fT4 – 0.93-1.7ng/dl fT3 - 3.5-7.8pmol/L TSH – 0.27-4.1 μ IU/ml Anti-TPO - <34.0IU/ml Tg - 3-40 ng /mL

9. Thyroid Disorders

10. Drugs for thyroid dysfunction

11. Reference Vasudevan-Textbook of Biochemistry Harper’s-Illustrated Biochemistry Gyton -Human Physiology KD Tripathi - Essential of medical Pharmacology Internet sources