Medical Staff Pulse Newsletter

New critical high value for potassium (K)

The serum potassium (K) critical value call back will change from >6.5 to >6.2 next month. The projected go-live date for this change is Wednesday, Sept. 26.

Both federal and California law mandate that clinical laboratories develop and follow written procedures for reporting imminent life-threatening laboratory results or critical values. In addition, clinical laboratories must immediately alert the individual or entity requesting the test, or the individual responsible for utilizing the test results, when a test result from among those defined by the laboratory in conjunction with the Medical Executive Committee indicates an imminent life-threatening condition.

Based on recent physician input, the current upper critical value for potassium is higher than the community standard and, on occasion, a patient may not be treated promptly for unexpectedly high potassium.

A review of the literature was conducted to compare Cedars-Sinai’s practices with the community. Based on an article in the Archives of Pathology and Laboratory Medicine, in a survey of 162 labs, critical value cut-offs for K of 5.9 is at the 5th percentile, 6.0 is median, and 6.5 is 95th percentile. (Arch Pathol Lab Med 2007;131:1769).

“We polled numerous doctors in the Department of Medicine, concentrating on those from the division of Nephrology, who would be most affected by this change,” said Holli M. Mason, MD, associate director of Transfusion Medicine and medical director of the Core Laboratory. “All of the physicians with whom we spoke felt that >6.5 was too high and favored lowering the cut off for a critical value call back.”

While there was some discussion on the best number (many favoring lower) it was generally agreed that a value of 6.3 (>6.2) would sufficiently cover patients in danger of an adverse event, while keeping the calls to a reasonable volume.

This proposed change has been presented to and approved by the Pathology PIC, the Medicine PIC, the CIC, and the Medical Executive Committee. Changes in the Laboratory Information System and standard operating procedures are expected to be completed by Sept. 26, when the new critical value will go into effect.