Growth hormone deficiency in childhood is apparent due to stunted growth, called dwarfism. As the affected child looks like a dwarf, the name “dwarfism” was coined. However, in adult life this is more difficult to diagnose.
With children, there is a lack of growth below the lower 3% of the growth curve when the growth rate is plotted on child growth charts. The physician or pediatrician measures the child’s measurements from time to time and keeps track of these values on a diagram that is especially designed to look for a drop below the lower acceptable limit. When this trend is apparent, the best for the family physician is to refer the child to a Children’s Hospital where the specialized staff can do the appropriate investigations that are necessary to find out why the growth rate is abnormal.
To complicate the picture, as mentioned in the introduction link (table “How does GH work?”) there are several factors that can inhibit GH and IGF-1 activity and sometimes more than one factor may be affected in this complex system. The endocrinologist has to carefully evaluate the various systems and pinpoint the cause(s).
GHRH stimulation test
One such test to check whether or not a defect in the hypothalamus might be responsible for dwarfism, is the GHRH stimulation test. Here the purified hypothalamic releasing hormone for GH is given by injection and the response to GH and /or IGF-1 is measured in the blood. A positive response indicates that the patient’s own GHRH production is missing and therefore there is a hypothalamic deficit that can then be further investigated with specific other tests (MRI scan etc.).
Here is a table that lists a few alternative causes for stunted growth in a child:
Some causes of short stature (dwarfism)
|Name of condition:||Explanation of defect:|
|rickets||lack of Vitamin D stops bone growth|
|hypothyroidism||lack of thyroid hormones stops growth|
|hypothalamic dysfunction||various causes (postradiation, tumor, postinfectious) leads to low IGF-1|
|Cushing’s syndrome||overproduction of cortisol by adrenal glands, weakens muscles|
|chromosomal abnormalities||defects in various parts of hormone axis|
|constitutional||delay in growth, but catching up later|
|chronic diseases||cystic fibrosis (lungs); kidney failure (electrolyte deficiencies etc.), Celiac disease (malabsorption) and others|
|malnutrition||protein deficiency (Kwashiorkor); syndrome of insulin resistance (too much sugar and starch, too little protein by default)|
As pointed out earlier, in adults the diagnosis of low GH activity is more difficult to spot. However, it likely is a factor of premature aging, of lack of energy, of thinning skin, dry brittle hair and a general contributor to reduced vitality.
Treatment of dwarfism
Only lack of growth hormone in children is treated with recombinant human growth hormone. In these patients often other hormones, such as thyroid hormone and cortisol, are also low or borderline normal and often they have to be replaced in childhood and adolescence as well to help normalize growth. A pediatric endocrinologist should supervise this complex hormone therapy.
1. B. Sears: “The age-free zone”. Regan Books, Harper Collins, 2000.
2. R.A. Vogel: Clin Cardiol 20(1997): 426-432.
3. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 8: Thyroid disorders.
4. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 7:Pituitary disorders.
5. J Levron et al.: Fertil Steril 2000 Nov;74(5):925-929.
6. AJ Patwardhan et. al.: Neurology 2000 Jun 27;54(12):2218-2223.
7. ME Flett et al.: Br J Surg 1999 Oct;86(10):1280-1283.
8. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 261: Congenital anomalies.
9. AC Hackney : Curr Pharm Des 2001 Mar;7(4):261-273.
10. JA Tash et al. : Urology 2000 Oct 1;56(4):669.
11. D Prandstraller et al.: Pediatr Cardiol 1999 Mar-Apr;20(2):108-112.
12. B. Sears: “Zone perfect meals in minutes”. Regan Books, Harper Collins, 1997.
13. J Bain: Can Fam Physician 2001 Jan;47:91-97.
14. Ferri: Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.
15. Rakel: Conn’s Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier