Laboratory Medicine Updates - April 7, 2003

 

 

University of Virginia Health System

Medical Laboratories

“Quality You Expect, Service You Deserve”

 

LABORATORY MEDICINE UPDATE

 

April 7, 2003

 

Informed Consent for HIV 1/2 Antibody Testing

 

Virginia law requires that “Prior to performing any test to determine infection with human immunodeficiency virus, the subject of the test shall be given an oral or written explanation of the meaning of the test.  Informed consent shall be obtained before such a test is performed.”

 

The official Health System form to use for HIV consent documentation is form # 030309.  This form is available in all out-patient clinics and in-patient areas and can be ordered by logging onto: http://www.virginia.edu/uvaprint/HSC/hs_forms.plThe form should be completed before testing is ordered and placed in the patient’s medical record.

 

A component of the Virginia law requires those ordering an HIV test to provide/offer follow-up HIV testing results, counseling and treatment/support options.  Health System policies 24 and 117 provide details applicable to the Health System.  In the event of a positive HIV test, the CDC recommends that patient care be provided by practitioners experienced in the management of HIV infection.  Counseling for these events may be supported by the HIV coordinator, available at 2-0084.

 

Change in Lower Limit for Troponin I Assay

 

Studies at UVa have demonstrated that cardiac Troponin I (cTnI) results < 0.08 ng/mL are so imprecise (CV > 20%) that quantification of such values adds no clinical information.  Such values are now reported as "< 0.08 ng/mL".

 

 

Sample Requirements for Troponin I Assay

 

The sample requirement for the cardiac troponin I (cTnI) assay is plasma.  Please submit a light green-top tube (minimum volume: 600 µL microtainer).

 

 

Critical Values for Mg2+ Results

 

An upper level critical value for Mg2+ results has been established at >8.0 mg/dL.  With this change, all patient results of <1.0 mg/dL and >8.0 mg/dL will be phoned immediately to the requesting physician.

 

 

Red Blood Cell Magnesium and Potassium No Longer Available

 

The tests RBC Magnesium and RBC Potassium have been removed from the test menu due to low frequency of ordering and lack of strong clinical evidence of their utility.

 

 

Sample Requirements for Cystic Fibrosis Mutation Analysis Testing

 

Due to poor quality DNA sampling, buccal swabs are no longer an acceptable specimen for CF mutation analysis, regardless of where the specimen is analyzed (University of Virginia, Quest, or Genzyme).

 

 

New Swab Collection Devices for Chalmydia/GC Samples

 

New collection devices for swab sampling for Chlamydia/GC analysis are now being stocked in the Hospital Storeroom (Bin number: 98812).  The Medical Laboratories will continue to accept the old collection devices.  The new device is a single package for both males and females containing a tube with media (Multi-Microbe Medium M4-RT) and a package containing two collection swabs (MicroGent/Swab Combo).  This collection device is not acceptable for viral culture, nor can this specimen be used for testing in addition to Chlamydia/GC (such as Herpes culture).

 

The process for sample collection has not changed.

 

For females: Wipe the exocervix with a large sterile swab (not provided with the collection kit), removing excess mucus.  Discard this swab and use the larger-bore swab provided with the collection kit to swab the endocervical canal for 3 to 5 seconds.  Withdraw and place the swab in the provided tube.  Break off the swab so that the top can be securely tightened on the tube.  The swab must remain in the transport tube.  Tubes may be stored at room temperature until transport to the laboratory.

 

For males: Instruct the patient not to urinate at least 2 hours prior to sampling.  Insert the smaller-bore (stainless steel shaft) swab provided with the collection kit into the urethra and rotate 3 to 5 seconds.  Withdraw and place the swab in the provided tube.  Break off the swab so that the top can be securely tightened on the tube.  The swab must remain in the transport tube.  Tubes may be stored at room temperature prior to transport to the laboratory.

 

Urine specimens are also acceptable with the reminder that patients should be instructed not to urinate at least 2 hours prior to providing a specimen for testing.  Urine specimens may also be stored at room temperature prior to transport to the laboratory.