Readers respond

Medical Laboratory Observer, May, 2009

A day in the life ...

Editor's note: The editorial office at MLO is never a dull place. Near the end of January, we received a telephone call from Ralph Henson in San Francisco, who asked a simple question: When and where was the term "point-of-care testing" coined? At one time, said Mr. Henson, today's POCT was known as "bedside testing" or "near-patient testing." He thought it might be one of our supplements, however, in one of his many last "good deeds," Dan Baer, MD, our "Tips" editor, suggested that I contact Peter Howanitz MD, who he believed, had been very active in this area through CAP.

Dr. Howanitz wrote back in response to our e-mail: "I do not know who coined the term point-of-care testing. At one time, the CAP coined and used the name 'alternate-site testing,' which others changed to 'alternative-site testing' for these tests. The term POCT had been used long before this testing started with glucose meters in hospitals in 1979. Perhaps Dr. Bear may reflect on the ward labs that many medical centers had for their residents and medical students where urines and hematocrits were done. This practice started long before my time or Dr. Baer's time."

Then Dr. Baer chimed in: "I think I found the answer to Ralph Henson's question about POCT. Gerald Kost's book, Principles and Practice of Point of Care Testing, begins with a brief history of POCT (page 3). Table 1 lists a chronology of guidelines and standards. There is a 1993 paper by Dr. Kost using the term POCT. This is the first use I see in the literature. On page three of the book, Kost writes, "Point of care is testing at or near the site of patient care. After more than 10 years of descriptive use, this term was codified when a group of multidisciplinary physicians, professionals, and leaders met at the national meeting of the Society of Critical Care Medicine in 1994 and selected this phrase and definition from competing alternatives. Later, representatives from this group and co-authors published a clarifying position paper." [From "The Laboratory-Clinical Interface" by P. Zaloga, R. Phillip Dellinger, Terry Shirey, Gerald J. Kost, Sharon S. Ehrmeyer, Bart Chernow, and James W. Winkelman in Chest 999;115;1140-1154.]

When we told Mr. Henson of our "discoveries," he sent a message: "Thanks for the update. I am very certain that the three MLO supplements which were sponsored by Mallinckrodt Sensor Systems were published within a period covering 1991 and 1992. The first reference that I can find for point-of-care testing is the MLO supplement to the September 1991 issue called 'MLO Special Issue: Point-of-Care Testing', which was sponsored by Maillinkrodt Sensor Systems, according to four different 'find articles.com' links.

Mallinkrodt Sensor Systems may well have been the first company to market its products using the term 'point-of-care testing;' and if my memory serves, the term was coined in about 1989 or 1990 by then product manager for Gem Systems, Ms. Cindy Flinn, who was trying to differentiate the Gem 'near-patient' blood gas/electrolyte analyzer from the ubiquitous 'bedside' glucometers. I seem to recall an evolution from 'testing at the point of healthcare delivery' to 'point-of-care testing' during that period of time--but I do not have any hard documentation to support that belief."

On this, our 40th MLO birthday, perhaps someone in MLO ReaderLand can help us pinpoint more information that would clarify POCT. We welcome your comments.

Peeling away misconception

Re: Lazzari, M. A harmful banana? MLO-online. April 2009, pp. 50-52.

This short case presentation certainly did a good job of highlighting the various causes of hyperkalemia. However, I wanted to take this opportunity to 'peel' away a common misconception regarding bananas and potassium. The foods highest in potassium are generally dried fruits, dates, juices, beans, trail mix, etc. (1) The potassium in prepared foods and fast foods can be, like sodium, way above the range found in natural food sources. Bananas are much lower, so why do they commonly get the bad 'wrap' for contributing to hyperkalemia? Generally speaking, unless there is some mental problem or renal disease, people do not get hyperkalemia from dietary sources. (2), (3), (4) Hyperkalemia is much more likely to be caused by disease and iatrogenic causes before natural food sources. Additionally, when advice is given to eat bananas for repleting lost potassium from renal losses (tubular disease, diuretics, etc.) or vomiting/NG suction, it is good to remember that most dietary sources of potassium are coupled with phosphates. The blood level of potassium will not normalize until the chloride is restored. (5)

[ILLUSTRATION OMITTED]

--Douglas E. Eglen, MD

Department of Pathology

Howard Regional Health System

Kokomo, IN

References

(1.) USDA National Agricultural Library. Available from http://www.nal.usda.gov/fnic/foodcomp/Data/SR20/nutrlist/sr20a306.pdf. Accessed April 23, 2009.

(2.) Berk DR, Conti PM, Sommer BR. Orange juice induced hykperkalemia in schizophrenia. IJPM. 2004;34(1):79-82.