Download MBBS Thyroid Lecture PPT

Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Thyroid Lecture PPT


THYROID.

? LARGEST GLAND IN THE BODY.

? FUNCTION =
1.Secretion of thyroxin.
2.Secretion of calcitonin.
SURGICAL ANATOMY.

? Weight---------20----25gm.
? Right and left lobe connected by isthmus.

? SITUATION= C5 to T1 vertebra.

? ISTHMUS = 2nd to 4th tracheal ring.

THYROID HORMONE.

? 1. THYROXINE (T4 ).
? 2.TRIIODOTHYRONINE (T3 ).
? 3.TSH.
? 4.Free T3.
? 5.Free T4.

HISTOLOGY

? FOLLICULAR CELLS------
? Lining the follicles

and secretes T3 and T4.

? Active phase---columnar
? Resting phase ---cuboidal.
? Follicles contains COLLOID.


? Parafollicular cells= secrete

CALCITONIN.

? Promote hypocalcaemia and calcium

deposition in bone.

? opposite to PTH.


Hormone synthesis.
HORMONE BIOSYNTHESIS.

IODINE TRAPING



FORMATION OF T3 and T4.

ORGANIFICATION

COUPLING REACTION.

? Binding of iodine with TGB.

? MAJOR PRODUCT =

? To form monoiodotyrosine

? THYROXINE

and diodotyrosine.

? 2 Molecules of

diiodotyrosine

? DIT + DIT = THYROXINE(T4).

? MIT + DIT = T3.
RELEASE OF T3 and T4.

T3 and T4 DIFFUSES OUT OF THYROID

CELL INTO SURROUNDING

CAPILLARIES.

PHYSIOLOGICAL ACTION.
REGULATION.

? Synthesis and liberation of thyroid hormone is

controlled by TSH = From anterior Pituitary.

? Secretion of TSH depend on level of T3 and T4.

= NEGATIVE FEEDBACK MECH........

? Regulation of TSH ----- By TRH From

HYPOTHALAMUS.

HYPERTHYROIDISM.

? A form of thyrotoxicosis due to inappropriately
High synthesis and secretion of thyroid hormones

by thyroid.

? Grave's disease is the most common cause, it is

due to IgG auto-antibodies to TSH called LATS-

long acting thyroid stimulator. They bind to TSH

receptor and continuously stimulate it leading to

increased T3 and T4 secretion.

? Toxic nodular goitre usually due to adenoma or

cancer of the thyroid.


COMMON SYMPTOMS.

? Excessive sweating
? Weight loss
? Heat intolerance
? Increased bowel movement
? Tremor
? Nervousness/agitation
? Rapid heart rate/palpitation.
? Insomnia
? Breathlessness
? Irregular or scant menstrual periods
Common signs

? Hyperactvity/hyperkinesis
? Sinus tachycardia
? Systolic hypertension
? Warm, moist, soft and smooth skin, warm

hand.

? Excessive perspiration
? Lid lag and stare(sympathetic overactivity)
? Fine tremor
Lab. Finding in hyperthyroidism.
DIAGNOSIS.

? 1.Typical clinical presentation
? 2.markedly suppressed TSH( < 0.05)
? 3.Elevated FT4 and FT3.
? 4.Thyroid antibodies
? 5.ECG to demonstrate cardiac manisfestation
? Nuclear scintigraphy to differentiate the cause.
role of imaging in hyperthyroidism.

? Thyroid ultrasound
? Colour doppler helpful.
? May reveal nodular disease or increased vascularity

( seen in Grave's )

? Thyroid uptake and scan
? High uptake
? Grave's, toxic MNG, Toxic adenoma
? Low uptake
? Thyroditis, iodine induced hyperthyroidism.

This post was last modified on 30 November 2021