Endocrinlogy

Question 1

Etiology of hypothyrodism

Answer 1

Primary congenital hypothyroidism:
a) Maldevelopment_and mal-descent of thyroid gland (nongoitrous)
= Agenesis (aplasia) is the most common
= Dysgenesis (hypoplasia) the gland is present but small and underdeveloped.
« Ectopic thyroid: the gland is usually dysgenetic and located anywhere between the root of the tongue and suprasternal notch
b) Dysmorphogenesis(goitrous)
Autosomal recessive inborn error of hormonal synthesis
c) lodine deficiency (endemic goiter): in Sinai and Oasis
d) Antenatal maternal intake of goitrogens: antithyroid drugs (e.g. thiouracil or radioactive iodine).

Question 2

Primary hypothyroidism:

Answer 2

thyroid gland lesion T3 and T4 are low while TSH is high.

Question 3

Secondary hypothyroidism:

Answer 3

pituitary or hypothalamic lesion: low TSH, T4 and T3