Test Details
Methodology
Liquid chromatography/tandem mass spectrometry (LC/MS-MS)
Result Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
Monitor therapeutic levels; evaluate toxicity
Limitations
This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.
Footnotes
Custom Additional Information
Mycophenolic acid (MPA) is the active metabolite of the prodrug, mycophenolate mofetil (MMF). Absorption of the prodrug is rapid following oral administration to the extent that detectable levels are not seen. Similar effects are observed after cessation of IV administration. Once formed, MPA undergoes metabolism to form the pharmacologically inactive phenolic glucuronide metabolite, MPAG. In vivo, MPAG is converted to MPA via enterohepatic recirculation, which results in a secondary peak in the plasma concentration time profile.1 MPA and MPAG are 92% and 87% protein bound, respectively, at usual clinical concentrations.
Recent reports have suggested that there could be a potential pharmacokinetic drug interaction between MPA and the calcineurin inhibitors. Several groups have observed that, in combination with cyclosporine, MPA serum concentrations are lower, and the MPAG serum concentrations are higher than in combination with tacrolimus.1
MPA has also been implicated as an adjuvant with highly active antiretroviral therapy (HAART) due to the selective inhibition of the conversion of inosine 5′-monophosphate to xanthosine 5′-monophosphate by the enzyme, inosine 5′-monophosphate dehydrogenase (IMPDH). Blocking this enzyme in lymphocytes depletes guanosine triphosphate (GTP) and deoxyguanosine triphosphate (dGTP) pools. This depletion of dGTP pools inhibits the activation of T lymphocytes, thereby limiting the availability of target cells for HIV.2
Specimen Requirements
Specimen
Serum or plasma
Volume
1.2 mL
Minimum Volume
0.3 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube or lavender-top (EDTA) tube
Collection Instructions
Transfer separated serum or plasma to a plastic transport tube.
Stability Requirements
Temperature | Period |
---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Storage Instructions
Room temperature
Causes for Rejection
Gel-barrier tube
LOINC® Map
Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
---|---|---|---|---|---|---|
716795 | Mycophenolic Acid and Metabo. | 87432-1 | 716796 | Mycophenolic Acid | ug/mL | 23905-3 |
716795 | Mycophenolic Acid and Metabo. | 87432-1 | 716797 | Mycophenolic Acid Glucuronide | ug/mL | 23906-1 |
Order Code | 716795 | |||||
Order Code Name | Mycophenolic Acid and Metabo. | |||||
Order Loinc | 87432-1 | |||||
Result Code | 716796 | |||||
Result Code Name | Mycophenolic Acid | |||||
UofM | ug/mL | |||||
Result LOINC | 23905-3 | |||||
Order Code | 716795 | |||||
Order Code Name | Mycophenolic Acid and Metabo. | |||||
Order Loinc | 87432-1 | |||||
Result Code | 716797 | |||||
Result Code Name | Mycophenolic Acid Glucuronide | |||||
UofM | ug/mL | |||||
Result LOINC | 23906-1 |