Laboratory Medicine Update - August 20, 2007

University of Virginia Health System

Medical Laboratories

"Quality You Expect, Service You Deserve"

LABORATORY MEDICINE UPDATE

August 20, 2007

Upper and Lower Respiratory Disease Allergy Profile

Medical Laboratories has created a new profile to help confirm or exclude atopy in patients with allergy-like respiratory symptoms.  This panel accurately identifies and quantifies specific allergen sensitivities in patients with confirmed allergy.  The allergens in the profile were selected based on regional pollen data and disease prevalence, as well as for their cross-reactivity with other comparable allergens.  This helps to ensure the most efficient detection of atopic sensitivities for patients in this region of the country.  The panel includes:  Bermuda Grass, Meadow / Kentucky Blue Grass, Johnson Grass, Cat and Dog Dander, Cockroach, House Dust Mite (Dermatophagoides farinea and pteronyssinus), Maple Tree, Elm Tree, Oak Tree, Pecan/Hickory Tree, Common Ragweed, Lamb's Quarter/Goosefoot, Cladosporuim herbarum, Aspergillus fumigatus, and Alternaria alternata.  A total IgE should also be requested when ordering this Respiratory Allergy Panel.

 

Lipoprotein-Associated Phospholipase A2 Testing

Recent publications have suggested that Lipoprotein-Associated Phospholipase A2 (LpPLA2) may predict 5-year cardiac mortality independently of established risk factors1.  Because of increased demands, testing for LpPLA2 has been implemented in the Davis Immunology Division of Medical Laboratories.  Specimen requirements are serum/gold-top tube and testing will be performed weekly.

1Winkler K, et al. Lipoprotein-Associated Phospholipase A2 Predicts 5-Year Cardiac Mortality Independently of Established Risk Factors and Adds Prognostic Information in Patients with Low and Medium High-Sensitivity C-Reactive Protein (The Ludwigshafen Risk and Cardiovascular Health Study).  Clin.Chem. 53:1440-1447 (2007).

 

New Reference Interval for Cortisol

Due to changes in the calibration of the serum/plasma cortisol assay, now set to match LC-MS/MS analysis, the reference interval for cortisol has changed to:

AM: 4 to 19 µg/dL

Values decrease during the day, generally reaching <50% of 0800 values by 2000.

 

D Test on MRSA

When a Staphylococcus aureus is identified as an MRSA, a D test is automatically set up to detect erythromycin-inducible clindamycin resistance. For erythromycin resistant MRSA isolates, the clindamycin result is only reported after completion of the D test.

 

Appropriate Specimens for Dermatophyte Screen

Dermatophytes are fungi that affect the deeper epidermal layers of the body, not the superficial layers of the skin and hair.  Swabs are, therefore, inappropriate collection devices and should not be used when submitting the specimen for a "Dermatophyte screen".  The preferred specimen is skin scrapings, nail scrapings or hair stubs submitted in a sterile or clean container.

 

Reminder: Fecal Lactoferrin Sensitivity Greater Than Fecal Leukocyte

In multiple studies, the Fecal Lactoferrin Test was found to be a more sensitive test for the detection of neutrophils associated with acute infectious conditions in feces than the Fecal Leukocyte test and to offer a better negative predictive value, even in breastfed children. While breast feeding lowers the specificity of the test, it does not affect the sensitivity. Other factors that require consideration when evaluating the specificity of the assay are non-infectious causes of inflammation and colonic inflammation caused by frequent exposure to infectious and parasitic agents (typical patients: children from developing countries). The Fecal Lactoferrin Test may be ordered through MIS, CareCast or on the Outpatient Test Request form.

 

HIV Genotyping and Resistance Reporting

Resistance interpretation (correlation of Protease and RT sequences to antiretroviral drug resistance) is based on interpretation of in vitro and in vivo phenotypic and virologic response data by The Consensus Panel, an international expert panel.  These include both primary and secondary mutations.

GuideLines Rules 12.0, using data available as of June 2006, is now available and will be applied to the Bayer TruGene HIV-1 Resistance reports.  Highlights of the new interpretation rules include:

  • Delavirdine (DLV) has been removed from the list of NonNucleoside RT Inhibitor drugs
  • Saquinavir (SQV) has been removed from the list of Protease Inhibitor drugs
  • Ritonavir (RTV) has been removed from the list of Protease Inhibitor drugs
  • Protease Inhibitor Rules for Ritonavir boosting of Darunavir (Darunavir + Ritonavir (DRV/r) have been added

 

REMINDER: In-patient MIS/Lab Order Rules for Blood Sample Collection

by Laboratory Phlebotomy Team

1. The phlebotomy team does not collect blood for laboratory testing in all in-patient locations. Orders for blood collection on units not served by the phlebotomy team will print as a collection reminder at the patient's MIS location. Units NOT collected by phlebotomy are: Angio, Cardiac Cath, ER, Urology OR and Recovery (Hospital West), KCRC, Labor and Deliver, Martha Jefferson Rucker 3, Short Stay Unit, Surgical Furlough Unit, Surgical Assessment/Pre-Admit, OR's, PACU, Newborn Nursery, Transition Nursery, NICU, PICU, MICU, NNICU, SICU, TCVPO, and CCU. When patients are transferred from an intensive care unit (not from a procedure area) to an acute care unit that the phlebotomy team serves, pending laboratory test orders are transferred by the Customer Service department of Medical Laboratories so specimens can be collected in the new location.

2. All STAT orders and Central Line blood collections are the responsibility of the units. Laboratory test orders for laboratory for patients with central line flags and tests ordered as STAT do not appear on the phlebotomy team's collection list, so neither the laboratory nor the phlebotomy team is aware of such orders.

3. TIMED orders are collected as close to the time requested as possible but the time of collection depends on the number of requests and availability of phlebotomy staff. All urgently timed samples, such as ACTH or cortisol response to administration of a drug, are the responsibility of the unit personnel.

4. Routine laboratory test orders for collection "Today" entered into MIS after 10 pm at night will be collected with others during the blood collection rounds beginning at 6 am the following day.

5. Routine laboratory test orders for collection "Today" entered into MIS between 6 am and 10 pm will be collected during the next phlebotomy rounds that same day.

6. Any order for a laboratory test entered into MIS without clicking on "Today" or "Tomorrow" will default to the next morning (6 am) phlebotomy rounds.

7. Between 6 am and 10 pm, phlebotomy collection rounds start every 2 hours beginning on the even-numbered hours. Every effort is made to have all samples collected and delivered to the laboratory within two hours of the start of the round. Due to the number of 6 am orders, completion of collection often requires between 3 and 4 hours.

8. The phlebotomy team collects only blood for TIMED laboratory tests between 10 pm and 6 am. Assistance with other blood draws can be requested during this time but can be provided only when workload and staffing permits.

9. Orders are evaluated and cancelled automatically by MIS when recognized as duplicates.

10. For units on which blood is collected by the phlebotomy team, discharge laboratory testing orders should be entered using the MIS Discharge pathway. The laboratory will collect the samples and the results will be available by 7:30 am on the day of discharge.