Homovanillic Acid/Vanillylmandelic Acid, Urine
|Epic Code:||LAB3552||Epic Name:||HVA AND VMA|
|Synonyms:||HVA and VMA, Urine; VMA and HVA, Urine|
|Methodology:||Capillary gas chromatography/selected ion monitoring mass spectrometry|
|CPT Code:||83150, 84585|
|Test Includes:||Quantitation of homovanillic acid (HVA) and vanillylmandelic acid (VMA) (mg/g urinary creatinine).|
|Turnaround Time:||Performed Mon-Fri; results are reported the next day.|
|Specimen:||Urine, random collection, 24 hr collection, or urine absorbed onto filter paper|
|Optimal Volume:||Submit entire collection; analysis requires 2 mL|
|Container:||Plastic leakproof container, sterile. Alternate: Filter paper; see collection instructions; 3 L plastic jug.|
If using filter paper to obtain collection, obtain filter paper urine collection kit from laboratory. The kit includes one 10 X 10 cm absorbent filter paper, patient identification form and directions for specimen collection. Collect as follows:
· In young infants, collect from a thoroughly wet diaper not contaminated with stool. Remove top layer of diaper if disposable type. Place filter onto diaper and place diaper on flat, hard surface. Place filter paper between two wet portions of diaper and press with fingertips until the filter becomes wet. Do this until the entire filter is damp (filter will look darker).
· Ultra absorbency diapers may present a problem in collecting enough urine and are not recommended for this collection. If ultra absorbency diapers are used, place several cotton balls between the diaper and the baby's genitals. The urine in the cotton ball can then be squeezed onto the filter paper.
· In toilet trained children, collect 5 mL urine.
Place filter paper on top of plastic bag or on a clean non-absorbent surface and let filter paper dry. Label filter paper with patient name and date in pencil (do not use ink). Place dried filter paper and identification form in a plastic leakproof bag.
|Patient Preparation:||Drugs such as L-dopa, dopamine, epinephrine and norepinephrine are metabolized to HVA and VMA and will fictitiously elevate their levels in the urine. Therefore, the patient should not be on such drugs when collecting the urine.|
|Causes for Rejection:||Not sufficient urine on the filter paper.|
Processing and Shipping
|Specimen Processing:||Aliquot 5 mL, 2 mL minimum. Store urine in refrigerator. Store filter paper at room temperature.|
|Shipping Instructions:||Ship urine at refrigerated temperature. Ship dry filter paper via regular US mail at room temperature. Express mail is recommended. Place the request form and dry filter paper in separate plastic transport bags prior to mailing.|
|Test Performed at or Referral Lab||Biochemical Genetics (UMMC-East Bank)|
|Use:||Diagnosis and monitoring treatment of neuroblastoma and pheochromocytoma. The combination of HVA and VMA will give a positive diagnosis in 92% of cases of neuroblastoma. More than 90% of patients with pheochromocytoma will have an elevated VMA. If both VMA and metanephrines are tested, >98% of patients with pheochromocytomas will be detected.|
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