Vanillylmandelic Acid (VMA)

Urinary VMA has an established role in evaluating children for neuroblastoma and can provide supporting information during follow-up. Neuroblastoma is a cancer that develops from immature nerve cells. Many of these tumors produce substances that eventually appear in urine as VMA or HVA, but some produce too little for these markers to detect.

For adults with spells of a pounding heart, sweating, headaches, or difficult-to-control blood pressure, plasma free metanephrines or urine fractionated metanephrines are the preferred initial tests for a suspected catecholamine-producing tumor. VMA misses too many cases to serve that role reliably.

What the Number Reflects

Adrenaline, noradrenaline, and dopamine belong to a group of chemical messengers called catecholamines. Your adrenal glands and sympathetic nerves produce them. The sympathetic nervous system helps regulate functions such as heart rate and blood pressure, including during the fight-or-flight response.

VMA is a major end product of adrenaline and noradrenaline breakdown. Much of it forms in the liver from intermediate products made elsewhere in the body, then passes into urine through the kidneys. Normal nerve activity contributes substantially to urinary VMA, which can make a tumor's additional contribution harder to detect.

This urine test uses LC-MS and reports VMA in mcg/g. For creatinine-corrected urine results, this expresses micrograms of VMA per gram of creatinine. Creatinine is a waste product made by muscles. Dividing by urine creatinine reduces the effect of urine dilution, although age and differences in creatinine production still affect interpretation.

Neuroblastoma in Children

VMA is usually assessed together with HVA when neuroblastoma is suspected. HVA is a breakdown product of dopamine. The two measurements complement each other because tumors differ in the substances they produce. Neither a positive nor a negative result establishes the diagnosis by itself; imaging and, usually, examination of tumor tissue are also needed.

A multicenter study compared spot urine panels using the tandem mass spectrometry version of LC-MS. This subgroup included 104 children with neuroblastoma and 571 children without neuroblastoma who were being evaluated for other conditions. The results below describe that study's assays and interpretation, not a guaranteed detection rate for this test.

The wider panel detected more tumors but also produced more false-positive results. A negative VMA and HVA result can therefore leave a suspected tumor unresolved, while an abnormal result from a broader panel needs careful interpretation.

Blood-based alternatives are also being studied. In one study, plasma normetanephrine and 3-methoxytyramine detected about 98% of neuroblastoma cases, compared with about 82% for urinary VMA and HVA. These are different molecules measured in a different specimen. The findings support their potential use in specialist evaluation and don't establish the accuracy of this urine assay.

What the Pattern Can Say About Tumor Biology

Some neuroblastomas produce relatively more dopamine and less VMA. In an observational study of 114 children, higher dopamine was associated with less favorable tumor biology, while higher VMA was associated with more favorable biological features. VMA by itself did not have a significant association with prognosis in that study.

These patterns offer clues about how a tumor makes and processes catecholamines. They don't establish its stage, prove that it carries extra copies of the MYCN gene, or determine treatment. Those decisions depend on the child's age, the extent of disease, and direct assessment of the tumor's tissue and genetic features.

Small human studies have also reported that urinary vanillactic acid and cystathionine helped distinguish neuroblastoma risk groups better than VMA alone. These are exploratory findings about additional urine markers, with clinical use still requiring further validation.

Monitoring During and After Treatment

Serial VMA measurements can provide supporting information when the tumor produced excess VMA at diagnosis. A persistent or renewed increase can raise concern about disease activity, but normal values can occur despite residual or recurrent neuroblastoma.

Urinary catecholamines are excluded from the revised International Neuroblastoma Response Criteria. Formal response assessment relies on imaging and other disease assessments, including bone marrow testing when relevant. A reassuring urine result cannot establish remission.

A recent study of children with high-risk neuroblastoma found that an extended eight-marker urine panel provided information about relapse risk during complete remission. VMA and HVA alone did not show the same predictive value. The panel was measured with that study's own laboratory methods, and the study did not validate this assay as a standalone predictor of relapse.

Why Routine Infant Screening Was Abandoned

Finding more neuroblastomas did not necessarily prevent more deaths. A German program that screened about 1.5 million children at around one year of age found additional tumors without reducing neuroblastoma mortality. Screening overdiagnosed tumors that might never have caused harm, including some that could regress spontaneously.

A smaller program in northern England used urine collected on filter paper. Among 20,829 infants, ten screened positive: two had neuroblastoma and eight did not. Three children with negative screens were diagnosed later. These were historical screening programs using different collection and laboratory methods from this test, but their results explain why population screening with urinary VMA and HVA is not recommended.

Adrenaline-Producing Tumors in Adults

Pheochromocytomas arise in the adrenal glands. Paragangliomas arise in related nerve-associated tissue elsewhere. Many of these tumors release catecholamines and can cause spells of palpitations, sweating, headache, and high blood pressure, although some produce little or none. An inherited predisposition raises the chance of developing a tumor; it does not itself establish excess hormone production.

In a historical study of 159 adults evaluated for pheochromocytoma, 25 had the tumor. VMA from a 24-hour urine collection detected 18 of those cases, while urinary free metanephrines detected all 25. The VMA measurement correctly tested negative in about 96% of people without the tumor, compared with about 94% for urinary free metanephrines. These results came from that study's collection and assay methods and should not be treated as performance estimates for this spot LC-MS result.

Metanephrines are formed continuously inside tumor cells, even between bursts of hormone release. That helps explain their advantage over VMA, whose signal includes substantial breakdown of catecholamines from normal tissues.

Why the Lab Method Matters

LC-MS stands for liquid chromatography with mass spectrometry. It separates chemicals in urine and identifies them using mass-related signals. Older color-based and electrochemical tests had different interference problems, so findings from those assays don't automatically describe this one.

Published LC-MS/MS assays have shown good agreement with older methods under controlled conditions, but each laboratory still has to validate its own accuracy and interference checks. A precision estimate from one published assay is not a guarantee for every LC-MS test.

When Results Can Be Misleading

• Illness and physical stress: severe illness, surgery, or intense exertion can alter catecholamine turnover and affect urine results without a catecholamine-producing tumor.
• Medicines that change catecholamine production or breakdown: levodopa can affect VMA and HVA. Older studies also found lower urinary VMA during phenelzine or imipramine treatment. Those studies used different assays, and the size of the effect on this test is uncertain.
• Interference with LC-MS detection: other compounds in urine can weaken or strengthen the measured signal unless the assay controls for them. The antibiotic trimethoprim-sulfamethoxazole can interfere with some clinical LC-MS/MS VMA assays, so the performing laboratory's interference information matters.
• Age and urine creatinine: creatinine-corrected values change with age. Differences in muscle mass and creatinine production can also affect the ratio, so dilution correction does not remove every source of variation.
• Collection and handling: the collection container, storage conditions, and any preservative must match the performing laboratory's requirements. A spot sample and a total 24-hour excretion result represent different measurements.

Food can still contribute to variation with modern methods. A small study using LC-MS/MS on 24-hour urine found that selected foods and a mixed diet sometimes produced modest VMA increases. It did not establish that preparation instructions can be ignored for every LC-MS assay or for a spot sample.