Homovanillic Acid and Vanillylmandelic Acid, Urine
HVA and VMA.
To assist in diagnosis of neuroblastoma, pheochromocytoma, and ganglioblastoma and to monitor therapy. VMA can also be useful in evaluation and follow-up of hypertension.
HVA: There are no food, fluid, or activity restrictions unless by medical direction. If possible, and with medical direction, patients should withhold acetylsalicylic acid, disulfiram, pyridoxine, and reserpine for 2 days before specimen collection. Levodopa should be withheld for 2 wk before specimen collection. The test should begin between 0600 and 0800 if possible. Usually, a 24-hr urine collection is ordered. As appropriate, provide the required urine collection container and specimen collection instructions.
VMA: There are no fluid restrictions unless by medical direction. Instruct the patient to abstain from smoking tobacco for 24 hr before testing. Usually, a 24-hr urine collection is ordered. As appropriate, provide the required urine collection container and specimen collection instructions. 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 (bananas, avocados, beer, aged cheese, chocolate, cocoa, coffee, fava beans, grains, tea, vanilla, walnuts, and red wine) for 48 hr before testing.
- The patient should not consume foods or fluids high in caffeine (coffee, tea, cocoa, and chocolate) for 48 hr before testing.
- 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.
|Age||Conventional Units||SI Units|
|Homovanillic Acid||(Conventional Units × 5.49)|
|3–6 yr||1.4–4.3 mg/24 hr||8–24 micromol/24 hr|
|7–10 yr||2.1–4.7 mg/24 hr||12–26 micromol/24 hr|
|11–16 yr||2.4–8.7 mg/24 hr||13–48 micromol/24 hr|
|Adult–older adult||1.4–8.8 mg/24 hr||8–48 micromol/24 hr|
|Vanillylmandelic Acid||(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|
|Adult–older adult||1.4–6.5 mg/24 hr||7–33 micromol/24 hr|
Critical Findings and Potential Interventions
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