Thyroid Disorders

Thyroid gland produces 2 hormones –

  1. Thyroxine or T4 and
  2. Triiodothyronine or T3.

Functions of the thyroid hormones are:

  • · They help in cell differentiation
  • · Maintain temperature and metabolism.
Thyroid Disorders

Thyroid Disorders Examination and Laboratory tests

Disorders of Thyroid are due to

  • 1. Overproduction ofthyroid hormone – Thyrotoxi­cosis
  • 2. Decreased production of thyroid hormone – Hy­pothyroidism
  • 3. Thyroid -nodules
  • 4. Thyroid cancers.
  • The thyroid glant has two lobes connected by an isth­mus.
  • Weight is 12-20 gms.
  • It is highly vascular and soft.
  • 4 parathyroid glands are situated behind the thyroid glands.
  • Thyroid medullary C cells produce calcitonin hormone which has the effect of lowering the calcium levels.

Abnormalities associated with development of thyroid gland may be

  • · Ectopic thyroid
  • · Lingual thyroid
  • · Thyroglossal duct cysts
  • · Thyroid agenesis
  • · Congenital hypothyroidism (1 in 4000 new-borns).
  • Thyrotoxicosis factitia is due to self administration of thyroid hormones and not a true thyroid disease.
  • TSH or thyroid stimulating hormone is secreted by anterior pituitary under the influence of TRH or thy­rotropin releasing hormone.

Biofeedback :

  • Thyroid hormones have a negative feedback on the release of TSH and TRH i.e.
  • when the level of thyroid hormones in the blood is high, TSH release is decreased.

Examination of the Thyroid

  • The skin is typically warm and moist, and the hair may be thin and fine.
  • The patient is examined from the front and side for· any masses, prominent veins or scar.
  • The thyroid is palpated from behind the patient with both hands. The patient is asked to swallow and the thyroid is palpated for size, consistency, nodules and tenderness.
  • The physical examination may be notable for hyperactivity and rapid speech.
  • Many patients have stare (lid retraction) and lid lag, representing sympathetic hyperactivity
  • In increased vasculatiry of the gland, a bruit is found over the gland.
  • In retrosternal goiters, venous distention is seen over the neck, with difficulty in breathing especially when the arms are raised above the head (Pemberton’s sign).
  • Tachycardia is common, the pulse is irregularly irregular in patients with atrial fibrillation, systolic hypertension may be present,
  • Lymphadenopathy of supraclavicular and cervical lymph nodes is examined.
  • Tremor, proximal muscle weakness, and hyperreflexia are other frequent findings.
  • Exophthalmos, periorbital and conjunctival edema, limitation of eye movement, and infiltrative dermopathy (pretibial myxedema) occur only in patients with Graves’ disease.

Thyroid Disorders Laboratory tests

  • TSH is assayed to see if level is suppressed, normal or elevated.
  • In primary abnormality of thyroid function, TSH level may be suppressed or elevated, but never normal.
  • In thyrotoxicosis, TSH is suppressed.
  • In hypothyroidism, TSH levels are elevated.
  • Always free T3 and T4 are estimated as the total T3 and T4 are highly protein-bound and are affected by illness or medications.
  • To confirm thyrotoxicosis, free T4 level elevation is sufficient.
  • Elevated TSH level is not enough to confirm hypothy­roidism, therefore TSH and free T4 should both be done.
  • Autoimmune thyroid disease is detected by measur­ing antibody against thyroid peroxidase and thyro­globulin.
  • Radio-iodine uptake and thyroid scanning helps to determine thyroid function and localize nodules and cancers.
  • Fine-needle aspiration biopsy of thyroid is used to evaluate thyroid nodules.
  • Thyroid ultrasound is used to detect nodule and cysts more than 3 mm.


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