Endocrine Causes of Short Stature

JK Looi
Monash Malaysia
Aug 24, 2007

Sources
•Evaluation of short stature
–http://student.bmj.com/issues/00/05/education/143.php
•Short Stature
–http://www.emedicine.com/ped/topic2087.htm
•Monash Lectures by Dr Choy and Prof Khalid
•Mauriac’s syndrome revisited
–http://www.springerlink.com/content/k50324232m4m874n/fulltext.pdf

Background
•Causes of short stature IS NICE

Endocrine causes
•growth hormone deficiency
congenital or acquired
(meningitis, trauma, irradiation)
•Hypopituitarism
•Hypothyroidism
•congenital adrenal hyperplasia
•diabetes mellitus
•pseudohypoparathyroidism

N.B.: Less common of non-endocrine causes

Revision
Let’s see what you can remember about Growth Hormone
•Patterns of GH secretion
•Biological effects

Patterns of release
•Episodic/pulsative/circardian secretion by ant pituitary gland
•Hypothalamic control on adeno-hypophysis
–GHRH stimulates
–Somatostasin inhibits
•Bound to GH binding protein in plasma
•Raised after meals, during deep sleep, exercise

Biological effects of GH
•Liver
–Stimulation of insulin-like growth factor (IGF-I)
•Body composition
–Lipolytic
–promotes retention of nitrogen
–protein anabolism (reducing plasma protein concentration)
–Improve muscle mass and strength
•Opposes function of insulin

GH insufficiency
•Slow growth velocity, delayed skeletal maturation, often overweight, dry skin, increase sc fat, crowding of facial features (maxillary hypoplasia, poor nasal bone development, delayed closure of fontanelles), delayed puberty

Laron dwarfism
•familial disorder; autosomal recessive
•Consanguinity a major contributor
•Lack of responsiveness of GH receptors
•Assay results:
–low serum IGF-I, but increased serum GH

Primary hypothyroidism
•Function of thyroid hormone in embryo/fetus/neonate/infant
–Brain maturation and skeletal development
•Low growth hormone pulsatility
•Slow growth, immature and delayed puberty
•Marked delay in bone age

Congenital Adrenal Hyperplasia
•Lack cortisol, lack aldosterone, excess androgen (21 hydroxylase deficiency)
•NB: In virilising form of CAH
•Testosterone leads to early growth plate fusion OR
•Administration of excess glucocorticoid for growth

Diabetes Dwarfism
•A.k.a. Mauriac syndrome
•low levels of insulin, inadequate diet and poorly controlled DM, with hepatosplenomegaly

Pathophysiology
•Inadequate control of the diabetes mellitus results in insufficient available tissue glucose.
•Gluconeogenesis and fat metabolism result in a catabolic state.
•Also, hyperglycemia has been associated with diminished somatomedin formation and somatomedin inhibitors in diabetic rats.
•Increased glycogen and fat storage in liver - hepatosplenomegaly

See you all in Segamat!!!

•Any questions?