Homovanillic Acid and Vanillylmandelic Acid, Urine

Synonym/Acronym

HVA and VMA.

Rationale

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.

Patient Preparation

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.

Normal Findings

Method: Chromatography.

Age	Conventional Units	Conventional Units
	Homovanillic Acid	Vanillylmandelic Acid
0–11 mo	Less than 35 mg/g creatinine	Less than 25 mg/g creatinine
1 yr	Less than 30 mg/g creatinine	Less than 22.5 mg/g creatinine
2–4 yr	Less than 25 mg/g creatinine	Less than 16 mg/g creatinine
5–9 yr	Less than 15 mg/g creatinine	Less than 12 mg/g creatinine
10–14 yr	Less than 9 mg/g creatinine	Less than 8 mg/g creatinine
15 yr–adult	Less than 8 mg/24 hr	Less than 8 mg/24 hr

Critical Findings and Potential Interventions ⬆ ⬇

Overview ⬆ ⬇

(Study type: Urine from a timed specimen collected in a clean plastic collection container with 6N HCl as a preservative; related body system: Circulatory, endocrine, and nervous systems. 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.)

HVA is the main terminal metabolite of dopamine. VMA is a major metabolite of epinephrine and norepinephrine. Both of these tests should be evaluated together for the diagnosis of neuroblastoma, one of the most common tumors affecting pediatric patients. Excretion may be intermittent; therefore, a 24-hr specimen is preferred. Creatinine is usually measured simultaneously to ensure adequate collection and to calculate an excretion ratio of metabolite to creatinine.

VMA is a major metabolite of epinephrine and norepinephrine. It is elevated in conditions that also are marked by overproduction of catecholamines. Creatinine is usually measured simultaneously to ensure adequate collection and to calculate an excretion ratio of metabolite to creatinine.

Indications ⬆ ⬇

Assist in the diagnosis of ganglioblastoma, neuroblastoma, and pheochromocytoma.
Evaluate hypertension of unknown cause.
Monitor the course of therapy.

Interfering Factors ⬆ ⬇

Drugs and other substances that may increase HVA levels include acetylsalicylic acid, disulfiram, levodopa, pyridoxine, and reserpine.
Drugs and other substances that may increase VMA levels include chlorpromazine, glucagon, guaifenesin, guanethidine, isoproterenol, methyldopa, nitroglycerin, oxytetracycline, phenazopyridine, phenolsulfonphthalein, prochlorperazine, and sulfobromophthalein.
Stress, hypoglycemia, hyperthyroidism, strenuous exercise, smoking, and drugs can produce elevated VMA.
Drugs and other substances that may decrease HVA levels include moclobemide.
Drugs and other substances that may decrease VMA levels include guanethidine, guanfacine, imipramine, isocarboxazid, methyldopa, monoamine oxidase inhibitors, and morphine.

Other Considerations

All urine voided for the timed collection period must be included in the collection, or else falsely decreased values may be obtained. Compare output records with volume collected to verify that all voids were included in the collection.

Potential Medical Diagnosis: Clinical Significance of Results ⬆ ⬇

Increased In

HVA excreted in excessive amounts in the following conditions:

Ganglioblastoma (tumor of the nervous system)
Hypertension
Neuroblastoma (tumor usually originating in the adrenal gland)
Pheochromocytoma (tumor usually originating in the adrenal gland)
Riley-Day syndrome (inherited disorder of the nervous system; also known as familial dysautonomia)

Catecholamine-secreting tumors will cause an increase in VMA.

Ganglioneuroma
Hypertension secondary to pheochromocytoma
Neuroblastoma
Pheochromocytoma

Decreased In

HVA is decreased in the following conditions:

Schizotypal personality disorders

Nursing Implications ⬆

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

Discuss how this test can assist in evaluating or identifying the presence of endocrine tumors
Explain that a urine sample is needed for the test. Information regarding urine specimen collection is presented with other general guidelines in Appendix A: Patient Preparation Specimen Collection.

Potential Nursing Actions

Include on the collection container’s label urine total volume, test start and stop times/dates, and any medications that may interfere with test results.

After the Study: Implementation & Evaluation Potential Nursing Actions

Treatment Considerations

Over-the-counter medications should be taken only under the advice of the patient’s health-care provider.
Discuss symptoms associated with pheochromocytoma as clinically appropriate: excessive sweating, headache, pallor, tremors, tachycardia, and shortness of breath.
Discuss symptoms associated with neuroblastoma as clinically appropriate: lumps under the skin that are not tender, protruding eyes, weight loss, pain (in the bones, back, chest, or abdomen), dark circles under the eyes, wheezing, constipation, or diarrhea.
Discuss symptoms associated with ganglioneuroma, which is slow growing and typically asymptomatic until found through examination for another condition. Symptoms that present are dependent on tumor location; chest presents with difficulty breathing, pain and trachea compression; abdomen presents with pain and bloating; spinal cord presents with deformity and strength loss in the arms, legs, or both.

Clinical Judgement

Consider who can provide the best emotional and therapeutic support for parents of children diagnosed with a tumor; consider the best way to approach a discussion of surgical and pharmaceutical interventions.

Follow-Up Evaluation and Desired Outcomes

Understands that additional testing may be necessary to evaluate or monitor disease progression and determine the need for a change in therapy.