HORMONE ACTION

Dr. Vijay Marakala, MBBS, MD.

Assistant professor BIOCHEMISTRY SIMS & RC

Polypeptides

Steroids

Amino acid derivatives

Insulinglucagonsomatotropin

FSHLHvasopressin

OxytocinthyrotropinACTH

Estrogentestosteronecortisol

AldosteronecorticosteroneProgesterone

Epinephrinenorepinephrinedopamine

Thyroxine, T3 and T4MelatoninSerotonin

Rule: All peptide hormones are synthesized asinactive “pre-pro” precursorsRule: All peptide hormones are synthesized asinactive “pre-pro” precursors

Rule: A signal peptide must be cleaved off to activate the mature form of the hormoneRule: A signal peptide must be cleaved off to activate the mature form of the hormone

MECHANISM OF HORMONE ACTION

Hormones transmit the signals through specific receptors

SIGNAL TRANSDUCTION

Definition: The series events and components thattake part in transmitting a hormonal signal to athe interior of the cell

Definition: The series events and components thattake part in transmitting a hormonal signal to athe interior of the cell

Membrane or cytosolic Receptor

Signal Initiator

Target molecule

Signal mediatorAction

SIGNAL TRANSDUCTION

RECEPTOR TYROSINE KINASES(e.g. Insulin Receptor)

THYROID FUNCTION TESTS

THYROID FUNCTION TESTS

T3 T4 TSH

Autoantibodies Free T4

T3

Reference range

• 110-190ng/dl

Increased T3

• Hyperthyroidism

Decreased T3

• Hypothyroidism

T4

Reference range

• 5-12µg/dl

Increased T4

• Hyperthyroidism

Decreased T4

• Hypothyroidism

TSH

Reference range

• 0.5-12µU/ml

Increased TSH

• Hyporthyroidism

Decreased TSH

• Hyperthyroidism

FREE T4

Direct measure of free hormones

07 – 2ng/dl

Estimation is more sensitive

THYROID AUTOANTIBODIES

Antibodies to TSH receptors

• Graves disease

Antimicrosomal antibody

• Hashimoto’s thyroiditis