Vanillylmandelic Acid, Urine
Vanillylmandelic Acid, Urine
To assist in the diagnosis and follow up treatment of pheochromocytoma, neuroblastoma, and ganglioblastoma. This test can also be useful in evaluation and follow-up of hypertension.
SpecimenUrine (25 mL) from a timed specimen collected in a clean plastic collection container with 6N hydrochloric acid as a preservative.
(Method: High-pressure liquid chromatography)
|Age||Conventional Units||SI Units (Conventional Units × 5.05)|
|3–6 yr||1–2.6 mg/24 hr||5–13 micromol/24 hr|
|7–10 yr||2–3.2 mg/24 hr||10–16 micromol/24 hr|
|11–16 yr||2.3–5.2 mg/24 hr||12–26 micromol/24 hr|
|17–83 yr||1.4–6.5 mg/24 hr||7–33 micromol/24 hr|
Vanillylmandelic acid (VMA) is a major metabolite of epinephrine and norepinephrine. It is elevated in conditions that also are marked by over production of catecholamines. Creatinine is usually measured simultaneously to ensure adequate collection and to calculate an excretion ratio of metabolite to creatinine.
This procedure is contraindicated for
- Assist in the diagnosis of neuroblastoma, ganglioneuroma, or pheochromocytoma
- Evaluate hypertension of unknown cause
Catecholamine-secreting tumors will cause an increase in VMA.
- Hypertension secondary to pheochromocytoma
- Drugs that may increase VMA levels include ajmaline, chlorpromazine, glucagon, guaifenesin, guanethidine, isoproterenol, methyldopa, nitroglycerin, oxytetracycline, phenazopyridine, phenolsulfonphthalein, prochlorperazine, rauwolfia, reserpine, sulfobromophthalein, and syrosingopine.
- Drugs that may decrease VMA levels include brofaromine, guanethidine, guanfacine, imipramine, isocarboxazid, methyldopa, monoamine oxidase inhibitors, morphine, nialamide (in patients with schizophrenia), and reserpine.
- Stress, hypoglycemia, hyperthyroidism, strenuous exercise, smoking, and drugs can produce elevated catecholamines.
- Recent radioactive scans within 1 wk of the test can interfere with test results.
- Failure to collect all urine and store 24-hr specimen properly will result in a falsely low result.
- Failure to follow dietary restrictions before the procedure may cause the procedure to be canceled or repeated.
Nursing Implications and Procedure
- Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
- Patient Teaching: Inform the patient this test can assist in evaluating or the presence of tumors.
- Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
- Obtain a history of the patient’s endocrine system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
- Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
- Review the procedure with the patient. Provide a nonmetallic urinal, bedpan, or toilet-mounted collection device. Address concerns about pain and explain that there should be no discomfort during the procedure.
- Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
- Usually a 24-hr time frame for urine collection is ordered. Inform the patient that all urine must be saved during that 24-hr period. Instruct the patient not to void directly into the laboratory collection container. Instruct the patient to avoid defecating in the collection device and to keep toilet tissue out of the collection device to prevent contamination of the specimen. Place a sign in the bathroom to remind the patient to save all urine.
- Instruct the patient to void all urine into the collection device and then to pour the urine into the laboratory collection container. Alternatively, the specimen can be left in the collection device for a health-care staff member to add to the laboratory collection container.
- Note that there are no fluid restrictions unless by medical direction.
- Instruct the patient to abstain from smoking tobacco for 24 hr before testing.
- Inform the patient of the following dietary, medication, and activity restrictions in preparation for the test (protocols may vary among facilities):
- The patient should not consume foods high in amines for 48 hr before testing (bananas, avocados, beer, aged cheese, chocolate, cocoa, coffee, fava beans, grains, tea, vanilla, walnuts, and red wine).
- The patient should not consume foods or fluids high in caffeine for 48 hr before testing (coffee, tea, cocoa, and chocolate).
- The patient should not consume any foods or fluids containing vanilla or licorice.
- The patient should avoid self-prescribed medications (especially aspirin) and prescribed medications (especially pyridoxine, levodopa, amoxicillin, carbidopa, reserpine, and disulfiram) for 2 wk before testing and as directed.
- The patient should avoid excessive exercise and stress during the 24-hr collection of urine.
- Potential complications: N/A
- Ensure that the patient has complied with dietary, medication, and activity restrictions and pretesting preparations prior to the procedure.
- Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
- Instruct the patient to cooperate fully and to follow directions.
- Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection.
- Obtain a clean 3-L urine specimen container, toilet-mounted collection device, and plastic bag (for transport of the specimen container). The specimen must be refrigerated or kept on ice throughout the entire collection period. If an indwelling urinary catheter is in place, the drainage bag must be kept on ice.
- Begin the test between 6 and 8 a.m. if possible. Collect first voiding and discard. Record the time the specimen was discarded as the beginning of the timed collection period. The next morning, ask the patient to void at the same time the collection was started and add this last voiding to the container. Urinary output should be recorded throughout the collection time.
- If an indwelling catheter is in place, replace the tubing and container system at the start of the collection time. Keep the container system on ice during the collection period, or empty the urine into a larger container periodically during the collection period; monitor to ensure continued drainage, and conclude the test the next morning at the same hour the collection was begun.
- At the conclusion of the test, comparethe quantity of urine with the urinary output record for the collection; if the specimen contains less than what was recorded as output, some urine may have been discarded, invalidating the test.
- Include on the collection container’s label the amount of urine, test start and stop times, and ingestion of any foods or medications that can affect test results.
- Promptly transport the specimen to the laboratory for processing and analysis.
- Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
- Instruct the patient to resume usual diet, fluids, medications, and activity, as directed by the HCP.
- Nutritional Considerations: Instruct the patient to avoid foods or drinks containing caffeine. Over-the-counter medications should be taken only under the advice of the patient’s HCP.
- Recognize anxiety related to test results, and be supportive of fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services.
- Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
- Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
- Related tests include angiography adrenal, calcium, catecholamines, CT renal, homovanillic acid, metanephrines, and renin.
- Related to Endocrine System table at the end of the book for related tests by body system.