Sorted By Test Name - Mayo Medical Laboratories

HVA
9253
HVAR
60275
Interpretation: Hyperhomocysteinuria could be caused by either genetic or nutritional factors. While
the highest levels are characteristic of classic homocystinuria, there are no reliable cut-offs to differentiate
between genetic or dietary causes of elevated homocysteine (HCY) levels. In our experience, very high
HCY levels have been seen in some patients with cystathione beta-synthase deficiency. HCY levels >9
mcmol/g creatinine are considered abnormal in patients under evaluation for cardiovascular or
neurovascular disease.
Reference Values:
Adults: 0-9 mcmol/g creatinine
Clinical References: 1. Mudd SH, Levy HL, Kraus JP: Disorders of transsulfuration. In The
Metabolic and Molecular Basis of Inherited Disease. Edited by CR Scriver, AL Beaudet, WS Sly, et al.
New York, McGraw Hill Book Company, 2001, pp 2007-2056 2. Klee GG: Cobalamin and folate
evaluation: measurement of methylmalonic acid and homocysteine vs vitamin B(12) and folate. Clin
Chem 2000;46(B):1277-1283
Homovanillic Acid (HVA), 24 Hour, Urine
Clinical Information: Homovanillic acid (HVA) and other catecholamine metabolites
(vanillylmandelic acid [VMA] and dopamine) are typically elevated in patients with
catecholamine-secreting tumors (eg, neuroblastoma, pheochromocytoma, and other neural crest tumors).
HVA and VMA levels may also be useful in monitoring patients who have been treated as a result of the
above-mentioned tumors. HVA levels may also be altered in disorders of catecholamine metabolism;
monamine oxidase-A deficiency can cause decreased urinary HVA values, while a deficiency of
dopamine beta-hydrolase (the enzyme that converts dopamine to norepinephrine) can cause elevated
urinary HVA values.
Useful For: Screening children for catecholamine-secreting tumors Monitoring neuroblastoma
treatment Screening patients with possible inborn errors of catecholamine metabolism
Interpretation: Vanillylmandelic acid (VMA) and/or homovanillic acid (HVA) concentrations are
elevated in over 90% of patients with neuroblastoma; both tests should be performed. A positive test
could be due to a genetic or nongenetic condition. Additional confirmatory testing is required. A normal
result does not exclude the presence of a catecholamine-secreting tumor. Elevated HVA values are
suggestive of a deficiency of dopamine beta-hydrolase, a neuroblastoma, a pheochromocytoma, or may
reflect administration of L-dopa. Decreased urinary HVA values may suggest monamine oxidase-A
deficiency.
Reference Values: