Vanillylmandelic Acid (VMA), Timed, urine

The measurement of VMA and HVA are crucial for the diagnosis and follow up of patients with neuroblastoma, pheochromocytoma and related tumors. Neuroblastoma is the most common solid malignancy of infancy with an occurrence rate of approximately one in every 7000 children under the age of 5. The tumors develop in utero and are present, though usually undetectable, at birth. Neuroblastomas arise in organs that develop from the embryonal neural crest. The tumors have morphological and biochemical features common to certain tissues of that lineage -- the sympathetic nervous system ganglia and the adrenal medulla. Abdominal neuroblastomas arise principally in the adrenal gland and extend into the retroperitoneal region. They may be revealed by the presence of a mass during routine examination by the pediatrician. The posterior mediastinum is a common site of tumors arising from paravertebral sympathetic ganglia. A variety of biochemical and genetic tests have been developed for routine clinical use. Neuroblastoma cells possess the metabolic pathways for the synthesis of catecholamines, and approximately 90% of tumors secrete elevated levels of catecholamines. Urinary HVA, the principal metabolite of dopamine, and urinary VMA, the principal metabolite of epinephrine and norepinephrine, have been measured in patients with neuroblastoma and proven to be valuable both in diagnosis and for monitoring therapy. The prognosis of patients with neuroblastoma is directly correlated with the patient's age and the stage of tumor spread at diagnosis. Children less than 1 year at diagnosis have a survival rate of 82%; those between 1 and 2 years have 32% and it drops to only 10% if diagnosis is made beyond 2 years of age. A VMA/HVA ratio greater than 1.5 is considered favorable in the prognosis