Homovanillic Acid (HVA), 24 Hour, Urine
Method Description Describes how the test is performed and provides a method-specific reference
Homovanillic acid (HVA) is measured in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Octadecyl (C18) solid-phase extraction is performed on a 1.2-mL aliquot of urine from a 24-hour collection. The solid-phase extraction column is eluted with 1.0-mL methanol. The eluate is evaporated at 30 to 40 degrees C under nitrogen, and the residue is reconstituted in 1.0 mL LC-MS/MS mobile phase. LC-MS/MS is performed by injecting 10 microL of the reconstituted specimen onto an amide-C16 HPLC column. The mobile phase (30% acetonitrile in 0.05% aqueous acetic acid) is pumped over the HPLC analytical column at the rate of 1.0 mL/min, with the flow diverted to the MS/MS electrospray probe tip by 1:5. HVA elutes apart from the bulk of the specimen matrix at a retention time of approximately 1.5 minutes. HVA is quantitated by using custom-synthesized stable isotope-labeled internal standard (C-4-hydroxy-O-HVA) from calibration over a concentration range of 1.04 to 16.7 mg/L. (Magera MJ, Stoor A, Helgeson JK, et al: Determination of homovanillic acid in urine by stable isotope dilution and electrospray tandem mass spectrometry. Clin Chim Acta 2001;306:35-41)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
2 days (not reported on Sunday)
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test