Laboratory Medicine Updates - July 17, 2002
University of Virginia Health
“Quality You Expect, Service You Deserve”
LABORATORY MEDICINE UPDATE
July 17, 2002
Antimicrobial Susceptibility Profiles 2001
Antimicrobial Susceptibility Profiles for 2001 are available for distribution in the form of pocket cards. Please call 4-8059 to order cards for your area.
Enterics Testing – Change in Location
Within the next month, fecal lactoferrin, Clostridium difficile and Helicobacter pylori testing will be performed by Medical Laboratories. These tests will no longer be available through the Enterics Laboratory.
Recent publications suggest that the fecal lactoferrin test is the preferred test for screening for inflammatory diarrheas. In most cases it demonstrates better sensitivity than the fecal leukocyte test. For the detection of enterohemorrhagic E coli (bloody stools) we recommend shiga toxin testing for the presence of toxin-producing E coli. The fecal leukocyte test is best used to rule out possible false positive lactoferrin test results.
We therefore recommend that the fecal lactoferrin test is the test of choice in screening for inflammatory diarrheas. The specimen submission criteria for all of these tests may be found in the laboratory Handbook or the Laboratory web page.
Hepatitis C (HCV) Genotyping – New in-house Test
Beginning July 15, 2002, the Molecular Pathology (DNA) laboratory will offer HCV genotyping analysis. The method employs RT-PCR and real-time PCR. The analysis of the different genotypes is performed using FRET probes and melting curve analysis on the Roche LightCycler.
Test Code: HCVG
CPT: 83891, 83902, 83898, 83896, 83912
Specimen Type: Serum (Gold Top)
Minimum Volume: 3 mL (500μL serum)
Add-on Limitations: May be added onto existing specimen in laboratory for up to 72 hours as long as the original specimen was refrigerated.
Turnaround Time: 10 working days
Results: Results will be reported as Type 1, Type 2, Type 3, or Type 4. In the event that there is not enough virus present to amplify, “none detected” will be reported. The division suggests a second sample be submitted at such time as the viral load is >15,000 IU/mL.
Please contact the Clinical Chemistry Resident (pic 1267) if you have questions.
Vidas D-dimer Assay Discontinued
The coagulation laboratory has discontinued the Vidas D-dimer assay by the ELISA method effective July 1, 2002.
The current method for any D-dimer assessment is the quantitative immunoturbidimetric method by Diagnostica Stage with a reference range of 0.00 to 0.42 FEU/mL. This D-dimer assay is orderable in MIS under the DD test code. For questions concerning the D-dimer assay, please contact the special coagulation laboratory at 4-8007.
New Reference Interval for Lupus Anticoagulant Screen
Due to a change in reagent, effective August 1, 2002, the reference interval for the Lupus Anticoagulant screen will be 29.5 to 46.3 seconds. The appropriate reference interval for the reagent used to perform an individual patient’s test appears on that patient’s report.
Ovarian Cancer Antigen 125
The reference interval for OCA125 has changed due to new reagents and instrumentation. The new reference interval is <21 U/mL. The laboratory will maintain the old instrument and reagents for a period of time. If you would like a sample analyzed by both the new and the old method, please contact the Davis Laboratory at 434-924-5179.
Prenatal Test Request Form
Please use the updated test request form when ordering TRIPLE or QUAD testing on pregnant women. This form is numbered 33386A revision 12/01 on the bottom left. If you do not have this form, please order it and discard all other versions. All the requested information on the form must be completed as accurately as possible in order to calculate the multiples of the median and assess risk.