3. Physiology
        3.3. Endocrinology
3.3.2. Growth hormone

Growth hormone

 

Growth hormone

Action of growth hormone

 

Insulin-like growth factor I (IGF-I, Somatomedin C)

Produced by liver

Increases in childhood and peaks at 13-17 yo

 

 

Insulin-like growth factor II (IGF-II)

 

IGF receptors

IGF-I receptor is very similar to insulin receptor.

IGF-II receptor is a mannose-6-phosphate receptor.

 

Growth hormone regulation

Increased by

Decreased by

NB:

[WG21:408] ???? Growth hormone does not seem to feedback to hypothalamus directly

IGF-I feeds back on anterior pituitary to reduce GH secretion

BUT, table 22-4 does show GH as one of the inhibitors

Growth

Once pubertal growth spurt started, linear growth continues even if caloric intake reduced.

2 periods of rapid growth

  1. in infancy
  2. in late puberty

Growth promoted by

Other notes

Achondroplasia

Most common from of dwarfism

Autosomal dominant

 

Short stature

Can be due to deficiency of GRH, GH, IGF-I, and others

GH-related causes are mostly due to GRH deficiency

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