What is Vanillylmandelic acid (VMA)?
It is a metabolite (breakdown product) of catecholamine hormones namely epinephrine (adrenaline) & norepinephrine. Catecholamine hormones are released by adrenal gland. Dopamine, epinephrine & norepinephrine are known to be primary catecholamines which are released in response to physical or emotional stress in body. These catecholamines after completing their action are metabolized i.e. norepinephrine into normetanephrine & VMA, while epinephrine into metanephrine & VMA. Both hormones and their metabolites are eliminated from the body via urine. Normally VMA is present in small amounts in urine but it is increased during & shortly after body gets exposed to a stressor.
What is VMA 24 hours urine lab test?
The VMA lab test is therefore used to measure VMA levels passed in urine typically over a period of 24 hours. This helps detect excess epinephrine & norepinephrine which happens due to tumors called neuroblastomas (cancer that develops from immature nerve cells in body) & other neuroendocrine (interaction between nervous system and glands that produce hormones) tumors. These neuroendocrine tumors produce catecholamines in large quantities resulting in increase concentration of hormones & its metabolites.
Why is VMA 24 hours urine lab test done?
The purpose behind this test is:
- It is useful in screening children for presence of catecholamine-secreting tumors with 24 hour collection of urine, when children should symptoms suggestive of the disease
- Support diagnosis of neuroblastoma
- For monitoring patients undergoing treatment of neuroblastoma (check effectiveness)
- To monitor for neuroblastoma recurrence
WHEN TO GET TESTED?
When your child has a lump in the abdomen (abdominal mass), bruising around the eyes, trouble walking, or bone pain; when you have symptoms of increased catecholamine release, such as persistent or periodic high blood pressure, severe headaches, rapid heart rate, and sweating; when you have been treated for neuroendocrine tumors, such as neuroblastoma.
- What is meant by elevated VMA?
Elevation in urinary VMA indicate that patient has tumor which secretes catecholamine hormones in excess. These tests diagnose adrenal gland tumor called pheochromocytoma.
- VMA in urine is what?
VMA and other catecholamine metabolites like homovanillic acid (HVA) measurement in urine basically screens catecholamine-secreting tumors in children
- What is considered normal VMA levels?
The level of 2 to 7 mg per 24 hours is considered normal for VMA
- How is urine collected for VMA test?
First you collect 24 hour urine specimen & add 25 mL of 50% acetic acid as a preservative.
- What are the symptoms felt during pheochromocytoma attack?
The tumor will release hormone that may cause rise in blood pressure, sweating, headache & symptoms of panic attack
Before taking this test, patient is advised to avoid medications like caffeine, phenothiazine, salicylates, & antihypertensive agents. In foods coffee, tea, fruit (especially banana & vanilla containing substance) & chocolate for 72 hours prior to collection of urine.
INTERPRETATION OF THE RESULTS:
VMA results are expressed as ratio of creatinine (waste product produced by muscles) excretion in mg/g cr. Also, VMA mass per day (mg/d) is not reported on specimen of patient younger than 18 years.
- “Vanillylmandelic acid – per 24 hours” in ages 18 & older: Ref interval is 0.0 to 7.0 mg/d
VMA-to-creatinine ratio is given when the patient is under 18 year or urine volume is less than 400 mL/24 hours:
- “Vanillylmandelic acid- Ratio to CRT” :
0-2 years 0-27 mg/g CRT
3-5 years 0-13 mg/g CRT
6-17 years 0-9 mg/g CRT
18 years and older 0-6 mg/g CRT
Creatine urine range in male & female for 24 hours:
- “Male”: 3-8 years 140-700 mg/d
9-12 years 300-1300 mg/d
13-17 years 500-2300 mg/d
18-50 years 1000-2500 mg/d
51-80 years 800-2100 mg/d
81 years and older 600-2000 mg/d
- “Female”: 3-8 years 140-700 mg/d
9-12 years 300-1300 mg/d
13-17 years 400-1600 mg/d
18-50 years 700-1600 mg/d
51-80 years 500-1400 mg/d
81 years and older 400-1300 mg/d
The test is performed to help diagnose or rule out the chance of having neuroblastoma or any other neuroendocrine tumor & for monitoring the effectiveness of the treatment.