Laboratory Medicine Updates - May 27, 2004
University of Virginia Health System
“Quality You Expect, Service You Deserve”
LABORATORY MEDICINE UPDATE
May 27, 2004
Antimicrobial Susceptibility Profiles
Antimicrobial susceptibility profiles for the most commonly isolated bacteria are available from the Clinical Microbiology division in the form of pocket cards for the year 2003. Please call 434-924-8059 to order cards for yourself and/or your location.
The Toxicology Laboratory has made two changes to testing for methadone in urine. First, the cut-off for the screening assay has been changed to 150 ng/ml (formerly 300 ng/ml). Second, urine will also be routinely tested for the primary metabolite, EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine), to confirm patient compliance. Methadone analysis is not a component of routine Drugs of Abuse testing but must be ordered separately. Please contact the Toxicology Laboratory a 434-924-2902 if you have any questions.
Serum, Urine, Hemoglobin Electrophoresis
The Medical Laboratories has implemented new equipment for electrophoretic analysis of serum, urine, and hemoglobin. Correlations with the new equipment (Sebia) show no loss of sensitivity or precision and improved immunofixation. Please contact the Davis Laboratory at 434-924-5179 if you have questions.
CA19-9 Tumor Marker
The Medical Laboratories will begin in-house testing for Cancer Antigen 19-9 on June 10. The assay will be performed on the Immulite 2000 using reagents from Diagnostic Products Corporation. The reference interval is <37 U/mL. Levels in a given specimen determined with different manufacturers can vary due to assay method and reagent specificity. The laboratory will test any sample with the previous reagent and method at no cost to the patient when requested to do so by the physician.
The Medical Laboratories will begin in-house testing for Cancer Antigen 15-3 on June 10. This assay replaces Cancer Antigen 27.29 as an aid in the detection of recurrence in previously treated stage II and stage III breast cancer patients and in the management of metastatic breast cancer patients by monitoring disease progression or response to treatment. The reference interval is <37 U/mL. Levels in a given specimen determined with different manufacturers can vary due to assay method and reagent specificity. The laboratory will test any sample with the previous reagent and method at no cost to the patient when requested to do so by the physician.
Changes in Reference Intervals
TSH: (Thyroid Stimulating Hormone): Beginning on June 10, 2004, the following age-dependent reference intervals will be used in the reporting of TSH values. The new pediatric values were derived from Hubner U, Englisch C, Werkmann H, Butz H, Georgs T, Zabransky S, Herrmann W. Continuous age-dependent reference ranges for thyroid hormones in neonates, infants, children and adolescents established using the ADVIA Centaur Analyzer. Clin Chem Lab Med. 2002 Oct;40(10):1040-7.
Age Reference Interval (mIU/mL)
0-4 day 0.13 - 9.2
5-30 day 0.16 - 8.5
1-12 months 0.29 - 6.0
1-3 y 0.40 - 4.9
4-6 y 0.44 - 4.8
7-12 y 0.49 - 4.6
13-18y 0.55 - 4.5
>18 y 0.45 - 4.5
BNP (B-Type Natriuretic Peptide): Several recent studies (Koch A, Singer H. Normal values of B type natriuretic peptide in infants, children, and adolescents. Heart. 2003 Aug;89(8):875-8; Redfield MM, Rodeheffer RJ, Jacobsen SJ, Mahoney DW, Bailey KR, Burnett JC Jr. Plasma brain natriuretic peptide concentration: impact of age and gender. J Am Coll Cardiol. 2002 Sep 4;40(5):976-82) have determined both age and sex dependent variation in the reference intervals for BNP. Based on the studies, the following reference intervals will be used in the reporting of BNP values beginning on June 10, 2004:
Age Males (pg/mL) Females (pg/mL)
<10 y <25 <25
10-18 y <13 <31
19-31 y <22 <45
32-44 y <31 <59
45-54 y <40 <73
55-64 y <52 <93
65-74 y <67 <120
> 75 y <86 <155
Orders for Additional Testing (Add-Ons)
Proper documentation is required in order for the Medical Laboratories to perform additional testing on specimens already in the laboratory (add-on testing). While physicians are no longer required to submit add-on requests only on a Medical Laboratories Requisition, the following steps are required in order to process the request. Failure to provide the requested information will cause the testing to be delayed or not performed.
Note: If all of the criteria of bullets c & d are not met, the test(s) will not be performed.