Test ID: POSA
Posaconazole, Serum
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Monitoring of posaconazole therapy
Method Name A short description of the method used to perform the test
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Posaconazole (Noxafil)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 2 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild OK; Gross reject |
| Other | Serum gel tube |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Frozen (preferred) | 14 days |
| Refrigerated | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Posaconazole interferes with fungal cytochrome P450 (CYP) (lanosterol-14 alpha demethylase) activity, decreasing synthesis of ergosterol, the principal sterol in fungal cell membrane, and inhibiting fungal cell membrane formation.(1,3)
Posaconazole has been approved for prophylaxis of invasive Aspergillus and Candida infections in severely immunocompromised patients (eg, hematopoietic stem cell transplant recipients with graft-versus-host disease [GVHD] or those with prolonged neutropenia secondary to chemotherapy for hematologic malignancies) and treatment of oropharyngeal candidiasis (including patients refractory to itraconazole and/or fluconazole).(1,2) It also is approved for ocular administration (drug monitoring not required for this use).
Posaconazole has a variable absorption. Food and liquid nutritional supplements increase absorption and fasting states do not provide sufficient absorption to ensure adequate plasma concentrations.(4,5) The drug has a high volume of distribution (Vd=465-1,774 L) and is highly protein bound (> or =97%), predominantly bound to albumin.(1,2) The drug does not undergo significant metabolism; approximately 15% to 17% undergoes non-CYP-mediated metabolism, primarily via hepatic glucuronidation into metabolites.(1) The half-life elimination is approximately 35 hours (range: 20-66 hours); steady-state is achieved after about 5 to 7 days. Time to maximum concentration is approximately 3 to 5 hours but, due to the highly variable absorption, trough level monitoring is recommended.
Therapeutic drug monitoring should be considered in the following situations:
-To document optimal absorption when used for prophylaxis or active treatment of a fungal infection
-Consider rechecking a level even if initial level was in the goal range if the patient:
- Is unable to meet optimal nutritional intake
- Is receiving continuous tube feeding
- Is receiving a proton pump inhibitor (decreased posaconazole levels in some studies)
- Has mucositis, diarrhea, vomiting, GVHD, or other reason that he/she may not absorb the drug well
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
>700 ng/mL (trough)
Interpretation Provides information to assist in interpretation of the test results
Greater than 700 ng/mL (>0.7 mcg/mL) has been suggested for prophylaxis and also in a salvage trial for treatment of invasive Aspergillus infections.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Package insert: Noxafil (posaconazole), Schering Corporation, Kenilworth, NJ, 2006
2. Physician's Desk Reference (PDR). 61st edition. Montvale, NJ Thomson PDR, 2007
3. Goodman & Gilman's: The Pharmacological Basis of Therapeutics. 10th edition. New York, McGraw-Hill Professional, 2001
4. Courtney R, Wexler D, Radwanski E, et al: Effect of food on the relative bioavailability of two oral formulations of posaconazole in healthy adults. Br J Clin Pharmacol 2004;57:218-222
5. Courtney R, Radwanski E, Lim J, Laughlin M: Pharmacokinetics of posaconazole coadministered with antacid in fasting or nonfasting healthy men. Antimicrob Agents Chemother 2004;48(3):804-808
Method Description Describes how the test is performed and provides a method-specific reference
Posaconazole is extracted into diethyl ether from alkaline serum. The diethyl ether layer is removed and dried down and reconstituted. The reconstituted sample is then injected into a liquid chromatography system and detected by tandem mass spectrometry. (Unpublished Mayo method)
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.
Tuesday, Thursday, Sunday; 11:30 p.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.
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
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
80299
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 89591 | Posaconazole, S | 53731-6 |
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