Laboratory Medicine Updates - 12/15/2000

expired

 

University of Virginia Health System

Medical Laboratories

"Quality You Expect, Service You Deserve"

 

LABORATORY MEDICINE UPDATE

 

December 15, 2000

 

REFERENCE INTERVAL CHANGES

 

 

Urine Creatinine:

 

The 24 hour urine creatinine reference interval for males has been changed to 0.8 – 2.8 g/24H. The reference interval for females remains unchanged at 0.8 TO 1.8 g/24H.

 

Anti-Microsomal Antibody:

 

"Negative" indicates the value is <2.0 IU/mL.

 

Anti-Thyroglobulin Antibody:

 

"Negative" indicates the value is <1.0 IU/mL.

 

Estradiol:

 

A new Estradiol assay reagent formulation allows measurement down to 30 pg/mL. The following reference intervals now apply:

 

Population

New Reference Interval

Male and female (prepubertal)

< 30 pg/mL

Adult males

30 – 56 pg/mL

Adult females

Early follicular phase

30 – 65 pg/mL

Mid-follicular phase

30 – 130 pg/mL

Late follicular/mid cycle phase

50 – 320 pg/mL

Early luteal phase

30 – 100 pg/mL

Mid luteal phase

30 – 200 pg/mL

Late luteal phase

30 – 160 pg/mL

Postmenopausal

<30 pg/mL

 

 

PROTIME (PT) REPORTABLE RANGE CHANGE

Protime results will now be reported up to 100.0 seconds.

 

NOW ORDERABLE IN MIS

Low (Ultrasensitive) HIV Viral Load:

 

The Low (ultrasensitive) HIV Viral Load assay is now orderable in MIS. It is listed on the same order screen as the HIV Viral Load assay. Reportable ranges for these two assays are:

 

Low (ultrasensitive) HIV Viral Load: 50 – 50,000 copies/mL

HIV Viral Load: 500 – 500,000 copies/mL

Indirect Neutrophil Antibody:

Indirect Neutrophil Antibody is now orderable in MIS and can be found under "N" using the Guide.

NEW TEST CODE FOR PSA – SCREENING VS DIAGNOSTIC

 

HCFA and Medicaid have now approved annual PSA determinations for screening purposes, distinct from the request for PSA for diagnostic purposes. Therefore, a second pathway for requesting PSA determinations has been added to MIS. Specific designation of requests for screening or diagnostic purposes will be added to the next revision of the out-patient test request form. In the absence of a specific designation, the laboratory will make the following assumptions.

  •  

  • For a PSA ordered with an ICD-9 code that begins with a "V" – the screening PSA will be ordered.

     

     

  • For a PSA ordered with any other ICD-9 code – the diagnostic PSA will be ordered.

     

Please note: There is no difference in the methodology used between these two tests. This is a CPT code/billing issue only.

 

ACID FAST BACTERIA SPECIMEN COLLECTION

 

Swabs are not appropriate collection devices for the culture of Acid Fast Bacteria (Mycobacteria sp.). The specimens of choice include fluid collected in a sterile black top tube and tissues, sputum, urine or bronchial samples collected in sterile containers. Specimens for Acid Fast Bacteria culture must be decontaminated by the microbiology laboratory prior to media inoculation. Therefore, the more sample provided, the greater the chances of recovery of any mycobacteria present.

 

TESTING FOR THYROID FUNCTION IN ICU PATIENTS

The evaluation of thyroid status in ICU patients is complicated. Studies here and elsewhere have indicated that routine free T4 tests can be misleading in such patients. For ICU patients, the Division of Laboratory Medicine and the Division of Endocrinology and Metabolism recommend that a full thyroid panel be ordered (TSH, total T4, T3-Uptake) rather that TSH with reflexive free T4. If the Free Thyroxine Index is low, and further evaluation of thyroid status must be undertaken while the patient is still in an ICU, free T4, by equilibrium dialysis (send-out test), may be required. The routine free T4 is not recommended.

 

HEPATITIS A TEST PERFORMED IN-HOUSE

The Medical Laboratories now offer Hepatitis A Total Antibody (IgG and IgM) as an in-house test. The preferred specimen type is serum (gold top tube) although plasma can be used for this assay. The minimum specimen volume is 1 mL whole blood. The test is performed once a week on Thursday and results will be available by 1700 the day the assay is performed. Results will be reported as NEGATIVE or POSITIVE, with NEGATIVE being the reference interval. This test may be ordered in MIS under "H" using the Guide.