Somatotropic hormone (STH; synonyms: somatotropic hormone; HGH or hGH (human growth hormone); HGH-N; HGH 1; GH (growth hormone); somatotropin ; somatropin; growth hormone) is a hormone responsible for body growth. It does not act directly for the most part, but indirectly via the somatomedins such as insulin-like-growth-factor (IGF-1). Other metabolic functions include: Protein biosynthesis (protein metabolism), fat turnover (lipolysis), and bone mineralization.
Somatotropin is a polypeptide (organic chemical compound formed from a linkage of several amino acids) produced in the anterior lobe of the pituitary gland (pituitary gland). Synthesis is controlled by the hypothalamus with somatotropin releasing factor (SRF). Somatotropin circulates largely unbound in the blood serum.
It is secreted primarily at night. A secretory stimulus (release stimulus) is provided by:
- Sleep (non-REM phase III)
- Stress
- Hypoglycemia (low blood sugar)
- Amino acids
Have an inhibitory secretory effect:
- Glucose
- Free fatty acids (FFS)
STH reaches its highest serum levels during puberty.
The process
Material needed
- Blood serum
Preparation of the patient
- Fasting blood collection
Interfering factors
- None known
Standard values
| Age | Normal values in ng/ml | Normal values in pmol/l |
| Newborn | 15-40 | 697,5-1860 |
| Prepuberty | 1-10 | 46,5-465 |
| Postpuberty | 0-8 | 0-372 |
| Umbilical cord blood | 10-50 | 465-2325 |
Indications
- Suspicion of disorders of growth
Interpretation
Interpretation of increased values
- Children: pituitary hyperglycemia – hyperglycemia caused by a disorder in the pituitary gland.
- Adults: acromegaly – enlargement of the acra (ends of the body) after completion of growth; caused by an excess of growth hormone.
Interpretation of lowered values
- Children: anterior pituitary insufficiency (HVL insufficiency) – inability of the pituitary gland to produce sufficient hormones; leads to growth retardation (growth retardation) to short or dwarfism.
- Adults: HVL insufficiency (with metabolic disorders of varying degrees), possibly indicating somatopause (natural decrease in STH production).
Other indications
- A single measurement alone is not sufficient to detect disease states because the concentration of the hormone changes quite rapidly; stimulation tests are more appropriate
