PROTOCOLS, PROTOCOLS, AND MORE PROTOCOLS

The BCMA/MSC Protocols Committee has issued two new initiatives. Details have previously been sent to all physicians in BC. The Hepatitis Protocol is designed primarily to automate the diagnosis of acute hepatitis. A copy of this protocol is included in this mailing. The other Urine Culture if Indicated protocol is designed to triage investigations of urinary infection. Below, we have provided a cautionary note about this approach. MDS Metro will be issuing a new requisition form later this summer. With the requisition, to relieve your bulging memories, we will provide a summary of all the current utilization protocols.

D-PYRIDINOLINE CROSS LINKS AND HYDROXYPROLINE

The availability of D-Pyridinoline Cross Links as a measure of bone resorption has rendered obsolete the measurement of Hydroxyproline as a cartilage breakdown marker. Hydroxyproline is not covered by MSP and has been discontinued. Requests for Hydroxyproline will be performed as D-Pyr. For those of you who want to learn more about bone markers, MDS Metro has a more detailed discussion available which can be obtained by calling 250-881-3109 on the Island or 604-431-5005, ext. 3094 on the Mainland.

URINE CULTURE IF INDICATED: POTENTIAL LIMITATIONS

The Protocol Steering Committee recently issued a protocol on urinalysis and urine culture for patients >17 years old. The protocol recommends a "urine culture if indicated option" based on the results of macroscopic or microscopic urinalysis.

In using the urine culture if indicated approach, it is important to be aware of the limitations of using urinalysis as a method to screen for bacteriuria.

• The results of studies in the literature are variable, but the correlation of a positive macroscopic urinalysis with bacteriuria >100 million CFU/L ranges from 79 to 93%.¹
• The sensitivity for detection of bacteriuria <100 million CFU/L is even lower, and urinalysis should not be used for detection of such levels of bacteriuria which can indicate significant infection.²

The variability of results in the literature suggests variation according to the patient population under study, and it is recommended that each institution evaluate urine screening methods in their patient population before instituting use of such methods.¹ Accordingly, we carried out a small evaluation of the performance of urinalysis for detection of bacteriuria in our patient population.

Of 217 sequential urine specimens that were requested for both culture and urinalysis, 41 were culture positive with significant bacteriuria. The urinalysis diagnostic performance was generally consistent with findings published in the literature:

• macroscopic urinalysis had 81% sensitivity and 79% specificity for detection of a positive culture.
• microscopic urinalysis had 71% sensitivity and 92% specificity for detection of a positive culture.

These results indicate that 20-30% of positive urine cultures will be missed if the "urine culture if indicated option" is ordered in our patient population.

Tests with less than 95% sensitivity are generally not recommended for routine use, and the urine culture if indicated option should be selected with caution.

References:

Koneman, et al. 1997. Color Atlas and Textbook of Diagnostic Microbiology, p. 140-141.
Murray, et al. 1987. Clinical Evaluation of Three Urine Screening Tests. J Clin Microbiol 25: 467-470.