Question

Long answer question

Describe in brief an account of disorders of the thyroid.

Answer 1

Disorders of the thyroid gland are caused due to hypersecretion and hyposecretion of thyroid hormones.

i. Hypersecretion of thyroid hormones: It is caused by an increase in the levels of thyroid hormones. This increases metabolic rate, sensitivity, sweating, flushing, rapid respiration, bulging of eyeballs, and affects various physiological activities.

Graves’ disease: Hyperthyroidism in adults results in this disorder. It is characterised by protruding eyeballs, increased BMR, and weight loss. Increased BMR produces a range of effects like increased heartbeat, increased B.P., higher body temperature, nervousness, irritability, and tremor of fingers.

ii. Hyposecretion of thyroid hormone: It is caused by a deficiency of thyroid hormones or removal of the thyroid gland (Thyroidectomy).

a. Cretinism: It is caused due to deficiency of thyroid hormones in infants. A cretin (individual suffering from cretinism) has reduced BMR and low oxidation. They are short-statured because the skeleton fails to grow. They are mentally retarded, show stunted growth and delayed puberty. They show dry skin, thick tongue, prolonged neonatal jaundice, lethargy and constipation. This can be treated by early administration of thyroid hormones.

b. Myxoedema: It is caused due to the deficiency of thyroid hormones in adults. It is characterised by a peculiar thickening and puffiness of skin and subcutaneous tissue particularly of the face and extremities. The patient lacks alertness, intelligence. The patient suffers from slow heart rate, low B.P., low body temperature (feels cold) and stunted sexual development.

c. Simple goitre: It is iodine deficiency goitre. Iodine is required for the synthesis of thyroid hormone and if there is a deficiency of iodine in the diet, it causes enlargement of the thyroid gland leading to simple goitre. This disease is common in hilly areas. Addition of iodine to table salt prevents this disease. The size of the thyroid gland is increased but the total output of thyroxine is decreased.

iii. Hyposecretion of thyroid hormones in pregnant females causes defective development and maturation of growing baby.