Vanillylmandelic Acid (VMA) Homovanillic Acid (HVA) Urine
Use
Diagnose pheochromocytoma, VMA is of value for evaluation of hypertension, diagnose and
follow up neuroblastoma, ganglioneuroma, and ganglioneuroblastoma. Most neuroblastoma
patients excrete excess HVA in 24-hour collections. If VMA and HVA are both used in work-
up, up to 80% of all cases will be detected
Some neuroblastoma patients are positive for urinary homovanillic acid abnormality but do not
excrete increased VMA. Twenty percent to 32% of patients with neuroblastoma do not have
elevation of VMA. Many will have other laboratory abnormalities such as increased
metanephrines, homovanillic acid (HVA), or dopamine
Specimen
Urine (24-hour) Record total 24-hour urine volume on the request form
Container
Plastic urine container (30 mL 6N HCl is optional;
Collection
If a specimen is to be stored longer than 5 days before analysis, add preservative prior to
starting the collection. Instruct the patient to void at 8 AM and discard the specimen. Then
collect all urine including the final specimen voided at the end of the 24-hour collection period
(ie, 8 AM the next morning). Measure and record total urine volume. Mix well; send aliquot.
Label container with patient's name, date and time collection started, and date and time
collection finished. Final pH must be 1-3.
Storage Instructions
Vanillylmandelic acid is stable at room temperature (15°C to 30°C) unpreserved for up to 5
days. Use 6N HCl to preserve specimens stored for longer than 5 days before analysis
Patient Preparation
Patient should avoid salicylates, caffeine, phenothiazine, and antihypertension agents. Also
coffee, tea, chocolate, fruit (especially bananas and any vanilla containing substances for 72
hours prior to collection).
Causes for Rejection Preservative not added to container if specimen stored longer than 5 days before analysis;
boric acid collection
Methodology
High-pressure liquid chromatography (HPLC) with electrochemical (EC) detection
Reference Interval
1.8-6.7 mg/24 hours
ودا ملف مرفق عن حالة الpheochromocytoma
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