Copeptin proAVP, Plasma
Use
The test is useful for investigating water balance disorders including diabetes insipidus, by measuring copeptin levels as a surrogate marker of AVP. It aids in the differential diagnosis by working in conjunction with osmolality and hydration status to distinguish between polyuria causes such as insufficient AVP or excessive water intake. It also plays a role in evaluating cardiovascular disease alongside other cardiac markers, potentially predicting heart disease outcomes when combined with BNP and proBNP markers.
Special Instructions
For water-deprivation testing, ensure the patient fasts and refrains from liquids for at least 8 hours prior to specimen collection. Collect the sample in a lavender top (EDTA) tube, centrifuge, and aliquot plasma into a plastic vial. Do not submit in the original tube.
Limitations
Copeptin concentrations can be affected by conditions such as sepsis, severe infections, chronic heart conditions, and AVP-related therapeutic interventions. Different causes of elevated copeptin such as ectopic secretion in bronchial carcinoma might necessitate expert consultation when interpreting results. There is also a potential for interference from human anti-mouse antibodies or heterophile antibodies in some cases. Interpretation of water-deprivation tests can vary based on protocols, and caution is necessary especially in mixed diabetes insipidus forms.
New York Approved
Methodology
Immunoassay (Immunofluorescent Assay (IFA))
Biomarkers
LOINC Codes
- 78987-5
- 78987-5
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
0.5 mL
Minimum Volume
0.3 mL
Container
Lavender top (EDTA); Plastic screw-top vial
Collection Instructions
Centrifuge, aliquot plasma into a plastic vial. Do not submit in original tube.
Patient Preparation
Fast and thirst for at least 8 hours (no liquids, including water) for water-deprivation testing.
Causes for Rejection
Gross hemolysis; Gross lipemia is okay
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 30 days |