| Test | : | 24Hr Metanephrine 1 - 17 y/o |
| Other Test Request Name | : | Not Applicable |
| Test Composition | : | - Metanephrine
- Normetanephrine
- Total Metanephrine
|
| Intended Use | : | Aids in diagnosis of pheochromocytoma, a tumor of the adrenal medulla Test is useful in the evaluation of pheochromocytoma. To help diagnose or rule out a rare tumor of the adrenal gland called a pheochromocytoma or a rare tumor outside the adrenal glands called a paraganglioma; these tumors (PPGL) produce excess cathecolamines, which are broken down to metanephrines. |
| Methodology | : | Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) |
| Laboratory Section | : | Special Test |
| Special Instructions/Patient Preparations | : | - Patient should avoid Tobacco, Tea, coffee for 3 days prior to specimen collection.
- Medications which are alpha agonists (Aldomet), alpha blockers (Dibenzyline) should be avoided 18-24 hours prior to specimen collection.
- It is preferable for the patient to be off medications for 3 days prior to collection. Consult your doctor before following this preparation.
Collection Procedures :
- Instruct the patient to void at the beginning of collection period and discard the specimen
- Collect all urine including the final voided at the end of collection period.
- Mix 24 hour urine collected.
- Label the bottle with patient name, date & time collection started, date and time collection ended and total volume measured.
- Note total volume.
- Submit the specimen to HPD.
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| Collection/Sample Container | : | Leak proof clean container without preservative |
Specimen and Volume Requirement Note:Follow tube manufacturer recommendation. | : | 100 mL of 24 hour Urine |
| Alternative Specimen and Volume Requirement | : | Not Applicable |
| Specimen Stability | | |
| • Room Temperature (15-25°C) | : | 2 Days |
| • Refrigerated Temperature (2-8°C) | : | 7 Days |
| • Freezer Temperature (-20°C) | : | 30 Days |
| Transport Temperature | : | Transport specimen at 2 – 8 °C (with cold packs) |
| Rejection Criteria | : | - Quantity not sufficient
- Received room temperature
- Improperly labeled specimen
- Improper urine collection
|
| Running Day | : | Batch Running |
| Cut Off Time | : | Monday, 12:00 PM |
| TAT/Releasing of Results | : | 2 weeks after cut-off (excluding Saturdays, Sundays and Holidays) |
| Reference Interval/Result Interpretation | : | Available upon request |
| Limitations/Interferences | : | - Common Antihypertensives (diuretics, ace inhibitors, calcium channel blockers, Alpha and Beta Blockers) cause minimal or no interference
- Medications which are alpha agonist (Aldomet), alpha blockers (Dibenzyline) may interfere with the assay.
- Substances from Tobacco, Tea, coffee may interfere with the assay.
|
| Frequently Asked Questions (FAQs) | : | Q: When to get tested? A: When your healthcare provider either suspects that you have a tumor that produces catecholamines or wants to rule out the possibility; when you (especially if you are younger than age 40) have sudden bursts (paroxysms) of signs and symptoms, such as high blood pressure (especially if it doesn't respond to standard treatment), severe headaches, rapid heart rate (palpitations), sweating, tremors and flushing; when you have a hereditary (genetic) risk for developing PPGL; when a tumor has been treated or removed, to monitor for recurrence; occasionally, when an adrenal tumor is detected incidentally, such as during an imaging test. Q: When is it ordered? A:Urine metanephrines are ordered when your healthcare provider either suspects that you have a tumor that produces cathecolamiomines or wants to rule out the possibility. It may be ordered when you (especially if you are younger than age 40) have sudden bursts (paroxysms) of signs and symptoms such as: - High blood pressure, especially when your hypertension is not responding to treatment (people with these tumors are frequently resistant to standard therapies)
- Severe headaches
- Sweating
- Flushing
- Rapid heart rate (palpitations)
- Tremor
Testing may also be ordered when a tumor that releases catecholamines has been treated or removed to monitor for recurrence. Occasionally, the test may be ordered when an adrenal tumor is detected by chance, such as during a scan conducted for another purpose, or when you have an inherited (genetic) risk or a family history of pheochromocytomas. Q: What does the result mean? A:Normal urine levels of metanephrine and normetanephrine mean it is unlikely that you have a tumor that produces cathecolamines. This test is very sensitive and these tumors are rare, so the negative predictive value of the test is very good. Elevated levels of metanephrine and normetanephrine when you have signs and symptoms suggest the presence of a tumor. Generally, two times the upper limit of normal is considered positive for total metanephrine. If levels are elevated after you have been treated for one of these tumors, it may be an indication that the treatment was not fully effective or that the tumor is recurring and appropriate follow up is needed. The test for metanephrines is very sensitive and false positives do occur. The test is affected by stress, drugs, smoking, and various foods. If you have only moderately elevated metanephrines, then your healthcare provider may re-evaluate your medications, diet, and stress level to look for interfering substances or conditions. Once these are resolved, you may be tested again to determine whether the metanephrines are still elevated. Q: Can I have more than one pheocromocytoma at once? A:Yes. Usually a single adrenal tumor will arise in one gland or the other, but multiple tumors can form. This is more likely in people with a strong family history of pheochromocytomas. You may have a tumor in each adrenal gland or occasionally in other locations. |
| Related Words/Test | : | Catecholamines, Plasma Free Metanephrines, Vanillylmandelic Acid (VMA) |