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The Essence: The Best of May 2019

By Anne-Margaret Olsson posted 06-10-2019 09:07

The Essence: The Best of May 2019

May was a busy month on the Artery, resulting in the highest number of total posts (including both new posts and replies) that we’ve had all year. To what do we credit this success? To you, the AACC members who understand that the Artery is a valuable resource where you can ask your tough questions and get the feedback and responses you need. In case you missed some of the solutions found on the Artery last month, below are our editor’s summaries of the May highlights.

Patient Request to “Take Back” Blood Drawn During Hospital Stay
Initiated by @Janet Simons, MD, FRCPC

What do labs do when patients request that their blood specimens be returned to them? Labs have received requests like this for reasons ranging from the religious to the more questionable (such as patients wanting to personally take their samples to another lab). When this does happen, one respondent advises labs to run these requests by their organization’s risk management department and attorneys, as the lab on its own does not have the expertise to determine whether such a request is valid.

Fasting Specimen of 75g OGTT
Initiated by @Yun Trull, PhD, DABCC

What protocol do labs follow when deciding whether or not to give a patient a 2h 75g OGTT? Many institutions send a fasting specimen to the main lab for glucose testing, and if the result is too high, they cancel the OGTT. Some labs also screen fasting samples prior to OGTTs with a glucometer. One Canadian lab that uses the glucometer option shared that if the result is above certain cutoffs, they do not administer glucola to the patient, and they then send the fasting sample off for main lab analysis to determine whether the patient has diabetes.

Pediatric Celiac Testing
Initiated by Danyel Tacker, PhD, DABCC, FAACC

For pediatric celiac testing, one institution’s pediatric gastroenterologists maintain that DGP-IgG rather than IgA should be tested if tTG-IgA is negative. Do other labs know the rationale for this? One respondent cited a number of celiac disease screening guidelines that support using DGP-IgG and/or IgA, particularly in children < 3 years of age (for whom tTG has poorer performance) and patients with possible IgA deficiency. Another respondent also thinks DGP-IgG might be more sensitive than DGP-IgA.

Pneumatic Tube Systems: Handle With or Without Gloves
Initiated by @Dawn Cornwall

Should facilities use standard precautions on both the lab and non-lab ends of pneumatic tube systems or is the non-lab end treated as clean? Respondents voted yes to the first option. To illustrate why, one respondent cited a time when urine samples spilled within her institution’s tube system. She also pointed out, however, that labs might have to educate the nursing team about proper pneumatic tube handling (for instance, her institution’s nurses were sending candy through the tube system to the lab and had to be asked to stop).

LDT Specificity and Sensitivity Determination
Initiated by @Tara Ward

How should a lab validate sensitivity and specificity for commercial assays that are considered laboratory-developed tests because they are being used off-label for body fluids? One respondent recommends using the following Clinical Laboratory Standards Institute protocols: EP17 for sensitivity and EP29 for specificity. Elaborating further, he says that for the former, labs should serially dilute the sample until it is below the Limit of Blank, while for the latter, labs should spike analyte in the sample and calculate spike recovery.