ACROMEGAL

YPAT H

OG

E NE S I S

GROWTH HORMONE

-Growth hormone is secreted by the somatotrophs of the anterior pituitary.

-It is essential for linear growth.

-It acts by producing a group of hormones called somatomedins.

-The prime somatomedin, Somatomedin-C is synthesised in the liver and in bone.

-Hypothalamic secretion of growth hormone releasing hormone (GHRH) stimulates GH secretion and Somatostatin inhibits it.

-Other neurotransmitters are also known to influence GH secretion (Dopamine stimulates GH secretion by stimulating GRH).

WHAT IS ACROMEGALY?

-It is a condition which results from excess secretion of growth hormone from Anterior Pituitary in adults after fusion of the epiphysis.

-A pituitary adenoma is usually the cause.

-They are usually classified by size and function.

•Microadenomas are <10 mm in diameter and cause clinical manifestations only if they produce excess hormone.

-Usually they are too small to produce mass effects. Nonsecretory microadenoma is common.

•Macroadenomas are >10 mm in diameter and may produce any combination of pituitary hormone excess.

- Pituitary tumours often reach the size of macroadenomas by the time the diagnosis is made.

-In rare cases ,GH excess is also caused by ectopic secretion of GH by carcinoid tumours and pancreatic islet cell tumours.

PITUITARY ADENOMA

ACROMEGALY-SIGNS AND SYMPTOMS

MANIFESTATIONS OF ACROMEGALY

CLINICAL AND ROENTGENOGRAPHIC FEATURES