Laboratory Medicine
Test Directory / Growth Hormone
Growth Hormone
Brown clotted serum, gel barrier
| Test | Growth Hormone |
|---|---|
| Common Abbreviations | GH |
| Profile | NA |
| Tube type | Brown clotted serum, gel barrier |
| Clinical Indication | Measurement of GH is primarily of interest in the diagnosis of inappropriate growth hormone secretion. Clinical disorders of hyposecretion include dwarfism and unattained growth potential. Hypersecretion is associated with gigantism and acromegaly. A single measurement of GH is usually of limited clinical value because GH secretion is pulsatile. To assess the clinical status of GH disorders, provocative or suppressive stimuli are often used. Provocative stimuli which cause an increase in serum GH levels are used if hyposecretion is suspected, these include exercise, sleep, insulin, clonidine, arginine, L dopa and glucagon. For suppression of serum GH levels, if hypersecretion is suspected, a standard glucose tolerance test is usually employed. |
| Specimen Type | Blood |
| Sample type | Serum |
| Minimum Volume | 0.5mL If requesting more than 10 tests please send an additional brown clotted serum sample. |
| Special Precautions | Patient should be fasting and at complete rest for 30 minutes before sample collection. |
| Stability | 8 hours at 20 - 25°C, 1 day at 2 - 8°C and 1 months at -20°C |
| Turnaround Time | Inpatient: 7 days Outpatient/ GP: 7 days |
| Laboratory | York |
| Reference Interval | None available for random GH measurement as levels vary with food intake, stress etc. For dynamic function testing: Repsponse to glucagon stimulation: >6.6 ug/L Response to insulin stress test: >16.6 ug/L Response to glucose tolerance test: <0.05 ug/L. |
| Limitations | Analysis should not be performed on haemolysed, icteric or lipaemic samples. The assay is unaffected by biotin < 123 nmol/L or < 30 ng/mL. No interference was observed from rheumatoid factors up to a concentration of 600 IU/mL. No interference was observed from IgG < 3.5 g/dL; IgA < 0.85 g/dL; IgM < 0.55 g/dL Samples should not be taken from patients receiving therapy with high biotin doses (i.e. > 5 mg/day) until at least 8 hours following the last biotin administration. In vitro tests were performed on 16 commonly used pharmaceuticals. No interference with the assay was found. The assay is affected by pegvisomant (a highly selective GH receptor antagonist) and is therefore not suitable for patients under pegvisomant treatment. There is no interference with Octreotide (somatostatin analogue) or Cabergoline (dopamine agonist). The assay is not suitable for the determination of GH in samples from pregnant women due to cross-reactivity to placental GH. Placental hGH is a variant of pituitary hGH37 and its serum levels increase during pregnancy. In rare cases, interference due to extremely high titres of antibodies to analyte specific antibodies, streptavidin or ruthenium can occur. |
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