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Nor-Metanephrine - Free Plasma
Blood
Report in 96Hrs
At Home
Fasting Required
Details
Catecholamine metabolites.
₹5,180₹7,400
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Nor-Metanephrine - Free Plasma Test Information Guide
- Why is it done?
- Measures free plasma nor-metanephrine, a metabolite of norepinephrine produced by the adrenal glands and sympathetic nervous system
- Primary indication: Screen for and diagnose pheochromocytoma and paraganglioma, catecholamine-secreting tumors that cause severe hypertension and other symptoms
- Evaluate unexplained hypertension, severe headaches, excessive sweating, palpitations, and anxiety episodes
- Assess patients with family history of pheochromocytoma or multiple endocrine neoplasia syndromes
- Monitor treatment effectiveness in patients with diagnosed pheochromocytoma
- Typically performed during initial diagnostic workup or when clinical suspicion warrants endocrine investigation
- Normal Range
- Reference Range: Less than 0.61 nmol/L (or <102 pg/mL, depending on laboratory assay)
- Units of Measurement: nmol/L (nanomoles per liter) or pg/mL (picograms per milliliter)
- Interpretation of Results:
- Normal Result: Values below 0.61 nmol/L indicate normal catecholamine metabolism; pheochromocytoma is unlikely
- Elevated Result: Values exceeding 0.61 nmol/L strongly suggest pheochromocytoma or paraganglioma; further confirmatory testing required
- Mildly Elevated: 0.61-0.95 nmol/L may warrant repeat testing or additional confirmatory studies
- Significantly Elevated: Greater than 0.95 nmol/L has high diagnostic sensitivity for catecholamine-secreting tumors
- Note: Reference ranges may vary by laboratory; consult specific lab reference values for accurate interpretation
- Interpretation
- Elevated Nor-Metanephrine Levels: Highly suggestive of pheochromocytoma or paraganglioma; indicates excessive norepinephrine release and metabolism
- Normal Nor-Metanephrine Levels: Makes pheochromocytoma/paraganglioma very unlikely; high negative predictive value for ruling out diagnosis
- Combined with Metanephrine: When both nor-metanephrine and metanephrine are elevated, pheochromocytoma diagnosis is more likely; only metanephrine elevated suggests different etiology
- Degree of Elevation: Greater elevations (>4-fold above normal) correlate with increased likelihood of active tumor
- Factors Affecting Results:
- Medications: Sympathomimetic agents, decongestants, stimulants, tricyclic antidepressants, and some antihypertensives can elevate levels
- Stress and Anxiety: Physical or emotional stress, pain, hypoglycemia, and anxiety can elevate catecholamine metabolites
- Sample Collection Issues: Improper collection, handling, or delayed processing can affect accuracy
- Position During Collection: Supine vs. upright position can influence results; should be specified
- Renal Dysfunction: Impaired renal clearance may affect metabolite levels
- Clinical Significance: Free plasma metanephrines have superior sensitivity and specificity for pheochromocytoma compared to urine metanephrines; abnormal results warrant imaging studies (CT/MRI) and consideration of genetic testing
- Associated Organs
- Primary Organ System: Adrenal glands (adrenal medulla); sympathetic nervous system
- Related Organs and Systems: Cardiovascular system (hypertension), nervous system, metabolic system
- Conditions Associated with Abnormal Results:
- Pheochromocytoma: Catecholamine-secreting adrenal medullary tumor causing severe hypertension, headaches, profuse sweating, palpitations, and anxiety
- Paraganglioma: Extra-adrenal catecholamine-secreting tumors arising from sympathetic or parasympathetic chain; may occur in abdomen, pelvis, chest, or head/neck
- Multiple Endocrine Neoplasia Type 2 (MEN2): Hereditary syndrome with pheochromocytoma in 50% of patients
- Von Hippel-Lindau Disease: Associated with pheochromocytoma in 10-20% of patients
- Neurofibromatosis Type 1: Associated with pheochromocytoma in 5-20% of patients
- Familial Paraganglioma Syndromes: Hereditary predisposition to paraganglioma development
- Potential Complications of Abnormal Results/Underlying Conditions:
- Hypertensive Crisis: Uncontrolled severe hypertension leading to stroke, myocardial infarction, or organ damage
- Cardiac Arrhythmias: Irregular heartbeat potentially progressing to life-threatening dysrhythmias
- Acute Pulmonary Edema: Can develop during hypertensive episodes
- Cardiomyopathy: Reversible catecholamine-induced cardiac dysfunction
- Metastatic Disease: Malignant paragangliomas can metastasize to distant sites requiring systemic treatment
- Follow-up Tests
- If Elevated Nor-Metanephrine is Found:
- Plasma Metanephrine: Measure metanephrine (metabolite of epinephrine) to determine if both catecholamines are elevated
- 24-Hour Urine Metanephrines: Confirmatory test to verify plasma findings; assesses total catecholamine excretion
- CT or MRI of Abdomen/Pelvis: Imaging to localize pheochromocytoma or paraganglioma; typically performed after biochemical confirmation
- MIBG Scintigraphy: Functional imaging using metaiodobenzylguanidine to detect catecholamine-producing tumors; high specificity
- PET Scanning: Positron emission tomography with fluorodopa or other tracers for tumor detection and staging
- Blood Pressure Monitoring: Regular measurement to assess hypertension severity and treatment response
- Genetic Testing: Consider RET, NF1, VHL, or SDHA/SDHB/SDHC/SDHD mutations if pheochromocytoma confirmed or family history present
- If Normal Nor-Metanephrine is Found:
- Clinical Reassurance: Normal results effectively exclude pheochromocytoma/paraganglioma with high probability
- Alternative Diagnosis Investigation: Pursue other causes of patient's symptoms (essential hypertension, anxiety disorder, thyroid dysfunction)
- Monitoring and Follow-up:
- Post-Surgical Monitoring: Annual testing for 5 years after pheochromocytoma resection to detect recurrence
- Genetic Syndrome Screening: Long-term surveillance with repeat testing every 1-3 years if syndromic pheochromocytoma/paraganglioma identified
- Treat-and-Repeat Testing: May repeat after discontinuation of interfering medications or resolution of stress factors
- Fasting Required?
- Fasting: NO - Fasting is not required for this test
- Patient Preparation Requirements:
- Rest Before Collection: Remain seated or supine for at least 5 minutes before blood draw to standardize results; supine position preferred for 30 minutes if possible
- Avoid Stress: Minimize physical activity, anxiety, and emotional stress for 30 minutes before test
- Temperature Control: Avoid extreme cold or heat exposure immediately before test
- Medications to Avoid or Discontinue:
- Decongestants (pseudoephedrine, phenylephrine): Discontinue 24-48 hours before testing
- Stimulant Medications: Amphetamines, methylphenidate, and other stimulants should be discontinued 24-48 hours before test
- Tricyclic Antidepressants: May interfere with results; consult provider about continuing these medications
- Sympathomimetic Amines: Avoid over-the-counter cold remedies and energy supplements
- Some Antihypertensive Agents: Certain medications may need to be held; consult with ordering physician
- Dietary Restrictions:
- No Specific Fasting Required: Patient may eat and drink normally
- Avoid Stimulating Beverages: Limit or avoid caffeinated drinks (coffee, tea, energy drinks) for at least 12 hours before test
- Avoid Tyramine-Rich Foods: Limit aged cheeses, cured meats, fermented foods, and soy sauce for 24-48 hours before testing
- Collection Instructions:
- Timing: Early morning collection recommended; collection time should be documented for result interpretation
- Position: Supine position for 30 minutes recommended before collection; if upright collection used, document position
- Sample Handling: Blood collected in appropriate tube (typically EDTA or specialty tube per laboratory); keep sample cool; avoid hemolysis
- Rapid Processing: Sample should be transported to laboratory on ice and processed promptly to prevent degradation of catecholamine metabolites
How our test process works!
