Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Clinical utility
Vanillylmandelic acid (VMA) [and Homovanillic acid (HVA)] is measured in urine for screening, diagnosis and monitoring children for neuroblastoma.
Clinical significance
Neuroblastoma is a neoplastic disease of infants and early childhood and is the third most common malignant cancer tumours in paediatric patients. Approximately 80% are found in children under 5 years of age. Elevated values of VMA (a metabolite of metadrenalines) and homovanillic acid (HVA, a metaboloite of dopamine), may be suggestive of the presence of neuroblastoma. VMA and HVA can be used for the diagnosis and follow up treatment of neuroblastoma. Early studies showed that the long term survival rate of these patients could be readily diagnosed using VMA/HVA ratios.
Specimen container paediatric:
White universal container
Specimen container adult:
White universal container
Minimum volume paediatric:
1 – 10 mL urine
Minimum volume adult:
1 – 10 mL urine
Special requirements:
Laboratory processing:
Do
- Upon receipt in laboratory, adjust pH to 3.0 to 6.0, and remove an aliquot for analysis.
- Store urine aliquot at 4°C prior to transport and analysis.
Do not
- over-acidify to pH <3.0
Sample stability:
Once pH has been adjusted to 3.0 to 3.5, samples are stable at 4°C for up to 10 days.
For long-term storage, store samples at –20°C.
Transport requirements:
For external laboratories:
Once pH has been adjusted to 3.0 to 6.0, transport urine aliquot at ambient temperature.
Freq Analysis:
1 x weekly
Quality Assurance:
UK NEQAS
Interpretation:
Vanillylmandelic acid (VMA) and/or HVA concentrations are elevated in more than 90% of patients with neuroblastoma; both tests should be performed. A positive test could be due to a genetic or nongenetic condition. Additional confirmatory testing is required. A normal result does not exclude the presence of a catecholamine-secreting tumor.
Elevated VMA values are suggestive of a pheochromocytoma, but they are not diagnostic.
Reference ranges:
| Age | HVA (µmol/mmol creatinine) |
| 0 to 6 months | <14.0 |
| 6 to 9 months | <14.0 |
| 9 to 12 months | <14.0 |
| 1-2 years | <12.5 |
| 2 to 3 years | <9.0 |
| 3 to 4 years | <7.5 |
| 4 to 5 years | <6.5 |
| 5 to 7 years | <6.0 |
| 7 to 10 years | <5.0 |
| 10 years to Adult | <4.5 |
Factors affecting result:
Administration of L-dopa may falsely increase VMA results. Patients receiving L-dopa should stop taking it for 24 hours before and during the collection. All patients receiving L-dopa should be identified to the laboratory when VMA and HVA tests are ordered.
Other Info:
Urine VMA analysis is performed by LC-MS/MS.