Laboratory Medicine Updates - September 29, 2006

University of Virginia Health System

Medical Laboratories

"Quality You Expect, Service You Deserve"

 

LABORATORY MEDICINE UPDATE

September 29, 2006

Bartonella species cultures

Due to an extremely low volume of requests, Bartonella cultures will no longer be performed in the UVA Clinical Microbiology Laboratory as of Oct. 1, 2006.  PCR and Bartonella Antibody Panels for IgG and IgM in serum can be performed by our referral laboratory, Mayo Medical Laboratories.  Please contact the Clinical Microbiology Resident on-call at pic 1852 if you have any questions.

 

Flow Cytometry Requirements

An order for TBNK (CD3, CD4, CD8, CD19, CD16, absolute CD4, and helper/suppressor ratio) or THS (CD3, CD4, CD8, absolute CD4, and helper/suppressor ratio) must have a simultaneous order for a CBCPR (CBC with profile) to allow for interpretation of results and to insure regulatory compliance.  Effective October 15, 2006, any order for TBNK or THS without an accompanying CBCPR will be canceled and the requesting location notified.

 

Requirement for Insurance Carrier Pre-Authorization

Insurance carriers in this region are increasingly requiring pre-authorization for testing they consider to be "genetic testing."  If pre-authorization is not sought and received and the testing is performed, your patient may receive a bill from Patient Financial Services.  Among the most commonly ordered test where this can be a problem are the following:

  • Factor V (Leiden)/Factor II
  • HLA Typing for reasons other than transplant
  • Hemochromatosis by PCR
  • Fragile X
  • Cystic Fibrosis (screening and diagnostic)
  • Cytogentic abnormalities
  • Any test for cancer, neurologic disorders, etc., associated with a mutation of the genome (FISH, sequencing, etc.)


Clarification: Urinalysis with Reflex to Culture

If you wish to order the Urinalysis with reflex to culture if indicated based on the urinalysis findings, please check only the "Urinalysis, reflex culture if indicated" box on the outpatient test request form.  If you wish to order a urinalysis with culture regardless of the urinalysis results, please check the "Urinalysis" and "Urine Culture" boxes on the outpatient test request form.  Any other combination of requests will require clarification to the laboratory and may delay testing.

 

Reminder: Fecal Leukocyte Stain Discontinued

Due to poor sensitivity of the Fecal Leukocyte Stain, this test is no longer available.  In multiple studies, the Fecal Lactoferrin Test was found to be a more sensitive test and offered optimal negative predictive value, even in breast-fed 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 include non-infectious causes of inflammation and colonic inflammation caused by frequent exposure to infectious and parasitic agents in children from developing countries.  The Fecal Lactoferrin Test can be ordered through MIS, CareCast or on the Outpatient Test Request form.

 

Reminder: CSF for culture of acid fast bacteria

CSF specimens will only be accepted for culture of acid fast bacteria (Mycobacterium spp. and Nocardia spp.) in consultation with and approval by the Microbiology Director-on-Call (PIC 1221).  Of 1,005 CSF specimens cultured for these organisms at UVA during the past five years, none were positive.  An alternative test is PCR-based, which must be sent to our referral laboratory. However, the sensitivity of that test is similar to culture and is therefore unlikely to provide diagnostic value.

 

Reminder: CSF Fungal Cultures to be replaced by Cryptococcal Antigen test

Fungal cultures of CSF will only be accepted after consultation with and approval by the Microbiology Director-on-Call (PIC 1221).  This change is due to the negligible yield of culture on this specimen type.

If a clinician suspects a patient has cryptococcal meningitis, it is recommended that a cryptococcal antigen titer be requested.  CSF specimens with negative titers are highly unlikely to yield positive cultures.  If a positive titer is obtained and the initial culture is positive, subsequent cultures may be valuable to help monitor the efficacy of antifungal therapy.  A consultation with Infectious Disease or the Microbiology Director-on-Call is recommended in these cases.