Growth Hormone, 180 Minutes
Also known as: GH 180
Use
The Growth Hormone, 180 Minutes test is designed to assess growth hormone (GH) secretion levels in patients and is useful in evaluating growth hormone deficiencies (GHD) or excesses. In pediatric patients, low peak GH concentrations on stimulation testing indicate severe GHD, whereas in adults, the expected peak concentrations depend on the stimulation test performed. For suppression testing, healthy individuals typically show GH concentrations of less than 1 ng/mL within 2 hours of glucose ingestion, with deviations potentially indicating conditions like acromegaly.
Special Instructions
The assay is standardized to the Recombinant Second International Standard (IS): 98/574, resulting in approximately 25% lower GH results compared to previous standards. Reference intervals have been modified accordingly. This test is approved by the New York Department of Health and follows the guidelines outlined by the Endocrine Society. It requires careful collection and handling of specimens to ensure accurate results.
Limitations
Very low thresholds to distinguish normal from partial GHD in pediatric patients have not been firmly established, possibly necessitating additional diagnostic tests. An inadequate response to two different provocative tests is typically required for a definitive diagnosis of GHD. Additionally, results may be influenced by factors such as patient preparation, proper specimen handling, and the specific GH stimulation test used. Reference ranges are susceptible to variance based on test standardization updates.
New York Approved
Methodology
Immunoassay (CLIA)
Biomarkers
LOINC Codes
- 56500-2
Result Turnaround Time
1-2 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL per timed specimen
Minimum Volume
0.4 mL per timed specimen
Container
Plasma Separator Tube (PST) or Serum Separator Tube (SST), also Green (sodium or lithium heparin), Lavender (EDTA), or Pink (K2EDTA)
Collection Instructions
Collect one tube per timed specimen. Allow specimen to clot completely at room temperature. Separate from cells ASAP or within 2 hours of collection. Transfer serum or plasma to individual ARUP Standard Transport Tubes.
Causes for Rejection
Tissue or urine. Grossly hemolyzed or lipemic specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | 1 week |
| Frozen | 2 months |