Elevated excretion of these compounds may also occur in Other disorders (eg, neuroblastoma, coma, dehydration, sleep apnea) Extreme stress Patients being treated with rauwolfia alkaloids, methyldopa, monoamine oxidase inhibitors, or catecholamines Ingestion of foods containing large quantities of VMA Other tests Blood volume is constricted and may falsely elevate hemoglobin and hematocrit levels.