Physicians, therefore use a combination of indirect and direct criteria in assessing GHD, including:
Auxologic criteria (defined by body measurements)
Indirect hormonal criteria (IGF levels from a single blood sample)
Direct hormonal criteria (measurement of GH in multiple blood samples to determine secretory patterns or responses to provocative testing), in particular:
Subnormal frequency and amplitude of GH secretory peaks when sampled over several hours
Subnormal GH secretion in response to at least two provocative stimuli
Increased IGF1 levels after a few days of GH treatment
Response to GH treatment
Corroborative evidence of pituitary dysfunction"Provocative tests" involve giving a dose of an agent that will normally provoke a pituitary to release a burst of growth hormone. An intravenous line is established, the agent is given, and small amounts of blood are drawn at 15-minute intervals over the next hour to determine if a rise of GH was provoked. Agents which have been used clinically to stimulate and assess GH secretion are arginine, levodopa, clonidine, epinephrine and propranolol, glucagon, and insulin. An insulin tolerance test has been shown to be reproducible, age-independent, and able to distinguish between GHD and normal adults, and so is the test of choice.
Severe GH deficiency in childhood additionally has the following measurable characteristics:
Proportional stature well below that expected for family heights, although this characteristic may not be present in the case of familial-linked GH deficiency
Below-normal velocity of growth
Delayed physical maturation
Delayed bone age
Low levels of IGF1, IGF2, IGF binding protein 3
Increased growth velocity after a few months of GH treatmentIn childhood and adulthood, the diagnosing doctor will look for these features accompanied by corroboratory evidence of hypopituitarism such as deficiency of other pituitary hormones, a structurally abnormal pituitary, or a history of damage to the pituitary. This would confirm the diagnosis; in the absence of pituitary pathology, further testing would be required. Classification
Growth hormone deficiency can be congenital or acquired in childhood or adult life. It can be partial or complete. It is usually permanent, but sometimes transient. It may be an isolated deficiency or occur in association with deficiencies of other pituitary hormones.The term hypopituitarism is often used interchangeably with GH deficiency but more often denotes GH deficiency plus deficiency of at least one other anterior pituitary hormone. When GH deficiency (usually with other anterior pituitary deficiencies) is associated with posterior pituitary hormone deficiency (usually diabetes insipidus), the condition is termed panhypopituitarism. Treatment
GH deficiency is treated by replacing GH with daily injections under the skin or into muscle. Until 1985, growth hormone for treatment was obtained by extraction from human pituitary glands collected at autopsy.