Homovanillic Acid, Urine (Sendout)

Ordering Recommendation: Initial test for the diagnosis and monitoring of neuroblastoma. May be ordered concurrently with VMA Quantitative, Urine (Sendout) [RUVMAQ].

Patient Preparation: Recommended to abstain from medications for 72 hours prior to collection.

Interpretive Data: Homovanillic acid (HVA) results are expressed as a ratio to creatinine excretion (mg/g CRT). No reference interval is available for results reported in units of mg/L. Slight or moderate increases in catecholamine metabolites may be due to extreme anxiety, essential hypertension, intense physical exercise, or drug interactions. Significant increase of one or more catecholamine metabolites (several times the upper reference limit) is associated with an increased probability of a secreting neuroendocrine tumor.

Per 24h calculations are provided to aid interpretation for collections with a duration of 24 hours and an average daily urine volume. For specimens with notable deviations in collection time or volume, ratios of analytes to a corresponding urine creatinine concentration may assist in result interpretation.

Moderately elevated HVA (homovanillic acid) may be caused by a variety of factors such as essential hypertension, intense anxiety, intense physical exercise, and numerous drug interactions (including some over-the-counter medications and herbal products).

Medications that may interfere with catecholamines and their metabolites include amphetamines and amphetamine-like compounds, appetite suppressants, bromocriptine, buspirone, caffeine, chlorpromazine, clonidine, disulfiram, diuretics (in doses sufficient to deplete sodium), epinephrine, glucagon, guanethidine, histamine, hydrazine derivatives, imipramine, levodopa (L-dopa, Sinemet®), lithium, MAO inhibitors, melatonin, methyldopa (Aldomet®), morphine, nitroglycerin, nose drops, propafenone (Rythmol), radiographic agents, rauwolfia alkaloids (Reserpine), and vasodilators. The effects of some drugs on catecholamine metabolite results may not be predictable.

Timed Urine:

• Collect urine for 24 hours in a preservative-free, amber polyethylene 24-hr urine collection container. Refrigerate during collection.
• Patient should record the collection start and stop dates/times.

Random Urine: Collect random urine in a screw-cap urine collection container.

Outside Laboratories:

• 24-Hr Urine:
  • Mix specimen well.
  • Measure and record the total volume. Note the collection interval and total volume on the requisition.
• Transfer 4 mL urine (min: 1 mL) to a separate aliquot. Refrigerate sample.

Stability: Refrigerated (preferred): 1 week, Frozen: 2 weeks; Ambient: Unacceptable.

24-Hr Urine:

• Mix specimen well.
• Measure and record the total volume. Note the collection interval and total volume on the requisition.

Random and 24-Hr: Transfer 4 mL urine (min: 1 mL) to a separate aliquot. Refrigerate sample.

Result at Entry:

• HVAINT: <Enter the collection interval in hours or RAND for random>
• HVATV: <Enter the total volume in mL or RAND for random>

Sendouts:

• Order ARUP Test: 0080422
• Interfaced: Yes [Interface: 602; Department: ARPR]
• For timed collections, include the collection interval and total volume in the ARUPConnect performing lab notes.

Stability: Refrigerated (preferred): 1 week, Frozen: 2 weeks; Ambient: Unacceptable.