 | Growth hormone deficiency: Encyclopedia II - Growth hormone deficiency - Diagnosis of growth hormone deficiency
Growth hormone deficiency - Diagnosis of growth hormone deficiency
Pediatric endocrinologists are the physicians who specialize in diagnosis and treatment of growth hormone deficiency and growth problems in children. Internist endocrinologists are the physicians with the most expertise in assessment and treatment of adult GH deficiency.
Although GH can be readily measured in a blood sample, testing for GH deficiency is constrained by the fact that levels are nearly undetectable for most of the day. This makes simple measurement of GH in a single blood sample useless for detecting deficiency. Physicians therefore use a combination of indirect and direct criteria.
Several types of evidence are used to ascertain GH sufficiency or deficiency.
- 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)
- 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, insulin, and Bovril.
Severe GH deficiency in childhood has the following measurable characteristics:
- Proportional stature well below that expected for family heights
- Below-normal velocity of growth
- Delayed physical maturation
- Delayed bone age
- Low levels of IGF1, IGF2, IGF binding protein 3
- 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
- Increased growth velocity after a few months of GH treatment
Severe GH deficiency in adults has the following measurable characteristics:
- Body composition has higher amount of body fat
- Subnormal bone density
- Diminished muscle strength
- Higher cholesterol levels
- Low IGF1 level
- Subnormal frequency and amplitude of GH secretory peaks when tracked over several hours
- Subnormal GH secretion in response to at least two provocative stimuli
- Increased IGF1 levels after a few days of GH treatment
When these features are 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, the diagnosis is confirmed and presumed to be lifelong. When these corroborative features are not present, further testing is needed to establish the diagnosis.
For GH deficiency, as for many other diseases, the practical purpose and effect of these diagnostic criteria is to determine who is to be treated with it. GH deficiency accounts for only a minority of short stature among children. GH deficiency accounts for an even smaller proportion of fatigability, excessive fat, osteopenic bones, and underdeveloped muscles in adults. An ideal diagnostic test cleanly separates people who would benefit from a treatment from those who would not. Unfortunately, none of the criteria listed above do so, not even in various combinations.
The common clinical problem is that many children and adults being evaluated meet some, but not all, of the above criteria. Since many children and adults who do not meet all of the diagnostic criteria may receive some of the benefits of treatment, small differences in the diagnostic criteria make large differences in the number of short or tired people diagnosed with deficiency.
Because of uncertainties and complexities of diagnosis and the high costs of treatment, diagnosis of growth hormone deficiency has been a more persistent subject of debate and controversy in clinical endocrinology than any other aspect of endocrine diagnosis. It has become a major type of internet fraud {HGH quackery}.
Other related archivesBovril, GH physiology, GH treatment, General Tom Thumb, HGH quackery, IGF1, Internist, P.T. Barnum, Pediatric endocrinologists, Sheehan syndrome, arginine, autoimmune, bone, bone maturation, brain tumors, cholesterol, clonidine, congenital malformations, craniopharyngioma, delays of motor development, diabetes insipidus, endocrinologists, epinephrine, excessive fat, fat, fatigability, genes, glucagon, growth, growth failure, growth hormone, growth hormone replacement, head trauma, hormone, human growth hormone, hydrocephalus, hypoglycemia, hypopituitarism, hypothyroidism, inflammation, insulin, intracranial tumors, jaundice, kewpie doll, leukemia, levodopa, maxillary, micropenis, microphallus, muscle, muscular, mutations, osteopenic bones, panhypopituitarism, penis, pituitary, polypeptide, poor bone density, propranolol, puberty, radiation therapy, recombinant DNA technology, sella turcica, septo-optic dysplasia, sex steroids, short stature, somatotropin, syringes
 Adapted from the Wikipedia article "Diagnosis of growth hormone deficiency", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki |
