Quick Facts
- Sample: Blood draw
- Fasting: Not required
- Turn-around: 5–7 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Advanced diagnostic accuracy — 97% accuracy for diagnosing water balance disorders
- More comfortable testing — Avoids lengthy water deprivation tests
- Superior sample stability — No special handling or shipping requirements needed
- Comprehensive health insights — Evaluates both fluid balance and cardiovascular risk
- Direct access — Get specialist-level testing without referrals
- Quick results — Receive actionable information within one week
Who Is This Test For?
- People with excessive thirst and frequent urination
- Individuals experiencing unexplained low sodium levels
- Those with suspected diabetes insipidus symptoms
- Patients with cardiovascular conditions or heart failure
- Anyone with persistent nighttime urination patterns
- People seeking water balance disorder evaluation
How It Works – Just 3 Steps
- Order online — Select your test and visit a nearby lab
- Quick blood draw — Simple collection requiring only small sample volume
- Get results — Review detailed report within 3-7 business days
FAQ
What does this test measure? Copeptin levels in your blood, which act as a stable marker for water balance hormones.
Do I need to prepare for this test? No special preparation required—maintain normal eating and drinking habits.
How accurate is this test? Studies show 97% diagnostic accuracy when properly interpreted by healthcare providers.
Can this test diagnose heart problems? It provides prognostic information for heart failure patients alongside other cardiac markers.
Is this better than traditional water tests? Yes—it's more comfortable and accurate than lengthy water deprivation tests.
What if my results are abnormal? Share results with your healthcare provider for proper interpretation and follow-up.
More Details
What is the purpose of this test?
The Copeptin Plasma Test measures copeptin, a stable peptide that serves as a surrogate marker for arginine vasopressin (AVP), also known as antidiuretic hormone. This test primarily helps diagnose and differentiate between types of diabetes insipidus, a disorder affecting water balance in the body (Mayo Clinic 2019).
Using advanced immunoassay technology, this test provides valuable insights into water balance disorders with superior stability compared to direct hormone measurements. The test also has important applications in cardiovascular disease assessment and prognosis, particularly for heart failure patients.
Who would benefit from this test?
Individuals experiencing symptoms such as extreme thirst, producing large amounts of dilute urine, and frequent urination would benefit most from this testing. It's particularly valuable when diabetes mellitus has been ruled out but symptoms persist (RequestATest 2024).
The test is also beneficial for patients with suspected cardiovascular conditions, particularly heart failure, where copeptin levels can provide important prognostic information. Healthcare providers may recommend this test for evaluating unexplained hyponatremia or investigating syndrome of inappropriate antidiuretic hormone secretion (SIADH).
When should I order a Copeptin Plasma Test?
Consider ordering when experiencing persistent excessive thirst, frequent urination (especially at night), or craving cold liquids. These symptoms are particularly concerning when they occur without an obvious cause or when diabetes mellitus has been excluded.
You should also consider this test if you have unexplained fatigue, confusion, or weakness potentially related to abnormal sodium levels. For individuals with known cardiovascular conditions, this test can provide additional prognostic information to guide treatment decisions.
How do I interpret the results?
Copeptin >21.4 pmol/L (baseline)
- What it means: Suggests nephrogenic diabetes insipidus
- Typical action: Specialist referral recommended
Copeptin ≤4.9 pmol/L (after stimulation)
- What it means: Indicates central diabetes insipidus
- Typical action: Hormone replacement therapy considered
Copeptin >4.9 pmol/L (after stimulation)
- What it means: Suggests primary polydipsia
- Typical action: Behavioral counseling may help
Copeptin ≥40 pmol/L (heart failure patients)
- What it means: Increased cardiovascular risk
- Typical action: Enhanced monitoring needed
Stimulation tests using hypertonic saline or arginine may be needed for accurate diagnosis of central diabetes insipidus.
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No specific preparation is typically required for basic copeptin measurement. Continue taking your medications as prescribed unless otherwise directed by your healthcare provider (UltaLabTests 2025).
Maintain normal hydration status before the test—avoid excessive fluid restriction or overhydration. If your test is part of a stimulation protocol involving hypertonic saline or arginine, your healthcare provider will give you specific preparation instructions.
How often should I get tested?
- Initial diagnosis workup: One-time with possible follow-up
- Monitoring treated diabetes insipidus: Every 6-12 months
- Heart failure risk assessment: Annually or as clinically indicated
- Symptom changes: As needed based on symptoms
Why early detection matters
Early identification of water balance disorders prevents serious complications including severe dehydration, electrolyte imbalances, and kidney damage. Untreated diabetes insipidus can lead to dangerous fluid and sodium level fluctuations.
For cardiovascular applications, elevated copeptin levels help identify heart failure patients at higher risk for poor outcomes, enabling earlier intervention. The combination of elevated copeptin and low sodium levels provides particularly strong prognostic information independent of other cardiac markers (Mayo Clinic 2019).
Related tests you may consider
Antidiuretic Hormone (ADH) Test — Provides direct measurement of the hormone that copeptin serves as a surrogate marker for, offering complementary information about water regulation.
Osmolality Test — These measurements provide crucial context for interpreting copeptin results and are essential for proper diagnosis of water balance disorders.
B-Type Natriuretic Peptide (BNP) — For cardiovascular evaluation, BNP provides complementary prognostic information alongside copeptin for enhanced heart failure risk stratification.
