Shedding light on

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Pictogramme horloge January 2015

Growth pathologies markers have two main indications:

  • in the child: failure to thrive because of growth hormone (GH) secretion deficit that may be either primary congenital or after a pituitary gland lesion (surgery or radiotherapy).
  • in the adult: acromegaly responsible for a typical dysmorphic syndrome with abnormal increased size of the feet and hands and a deformation of the face over the years, most commonly after a pituitary gland adenoma.

The 3 main markers are:

  • GH (growth hormone)
    • Polypeptide hormone synthesised, stored and secreted at the level of the anterior pituitary gland.
    • This acts by means of a main effector: IGF-1
    • Its main disadvantage is its pulsatile mode of secretion with mainly night peaks related to different stages of sleep, but also in the day related to mealtimes and stress. The presence of periods where the secretion is not detectable makes its dose of little use on repeated samples.
    • Its main advantage is being the only growth marker to response to pharmacological stimulations (two concordant tests are essential to enable prescription of growth hormone) and slowing down by OGTT (oral glucose tolerance test) which, if effective, eliminates an acromegaly.
  • IGF-1 (insulin-like growth factor)
    • Single-strand peptide synthesised under the action of GH, 50% in the liver and 50% in the chondrocytes of growth cartilage.
    • Its main advantage is having quite a constant secretion over a consecutive period of 24 hours. This is therefore a correct reflection of the impregnation of the body with GH.
    • It is the first intention test to screen for GH deficit in the child aged under 10 and for acromegaly.
    • Its reference values vary greatly according to age, sex and nutritional status. Moreover, a reduced rate in the child aged under 10 especially does not always signal a GH deficit in this age group.
  • IGFBP3 (insulin-like growth factor binding-protein3)
    • Protein carrying IGF-1 synthesised mainly by the liver.
    • Its variations according to age and sex are less significant than those for IGF-1.
    • Its reduction in states of malnutrition is also less than that for IGF-1.
    • Its main advantage is having better sensitivity to screen for GH deficits in children aged under 10. It should therefore be prescribed as first intention in this age group alongside IGF-1.