Academy of Diagnostics & Laboratory Medicine - Scientific Short

Creatinine: Critical Value Worthy or Not?

David Alter

Critical value notification is a CLIA mandated laboratory practice whereas providers need to be urgently notified of any “…any test result that indicates an imminent life threatening condition...”.  However, CLIA does not specify which tests (or associated values) are considered “imminently life threatening”.   In theory, there is no test that ultimately doesn’t have an “imminently life threatening” value but, in my opinion, the requirement implies a focus on those test/value combinations that could occur relatively independent of other laboratory findings and with minimal symptomology.  Expectedly, multiple deranged test results and/or pronounced clinical findings obviate the need for a single laboratory result alert/panic value.   Based on that logic, one could argue that there are only a very small number of test/result combinations that are truly imminently life threatening. Some of which include the following: very low hemoglobin; very low glucose; extreme high/low potassium; new onset blasts or CSF positive for bacterial organisms; all of which can present clinically silent until emerging with serious life threatening sequelae. Over the last 30 years, multiple reviews and discussions on suggested critical tests and limits been published in the medical literature (1-7).  Readers are recommended to review these as well as do their own searches.

One contentious critical/value combination has been the inclusion, or not, of creatinine and, if so, where to set its critical cutoff.  The root of the question lies with the question: when does an elevated creatinine level by itself represent an imminently life threatening condition and at what level?  Acute elevations in serum creatinine levels do occur but are typically in response to acute etiologies of renal failure which are typically not imminently life threatening and when due to life threatening conditions; the clinical picture and etiology is usually quite evident e.g shock secondary to “pick your etiology”.

In the typical hospital laboratory setting, markedly elevated creatinine values are endemic with presumably most of them due to known patients on dialysis or with late stage chronic kidney disease. Consequently, calls placed for the majority of these patients results in an unnecessary utilization of precious laboratory resources and incur client dissatisfaction (being called for known issues) with the number of calls increasing as the cutoff value goes lower.  Alternatively, strategies to control when and which critical creatinine values to call such as “only first value in record/visit”; only inpatients; only outpatients; creatinine levels with a marked positive delta change and so on are possible and effective. However, these algorithms are limited by available resources i.e. lack of  personnel (or middleware) to review patient records on every elevated creatinine to identify only those values that should be called.

An ad-hoc random survey that I conducted via the AACC listserv several years ago asked the question: “Do you have a critical value for creatinine and, if so, what is it set at?”  I had 26 responses and they are summarized below.  In addition, for this discussion, I did a GOOGLE search of the terms “critical value” and creatinine. The first 14 institutions are listed below. 

 

AACC Listserv responses

Response- Critical Value (mg/dL)

#respondents

No critical values

15

Specific value (>10)

3

Specific value “>” (3; 5; 6; 7; 9; 2.5&<18 years old; delta 1.5; ) with modifying protocol e.g no dialysis, no inpatients etc.

8

 

GOOGLE Internet Search

Critical Value (mg/dL)

# Hospitals

No Critical Value

5

4

2

5(one was only for the first time)

2

7.5(one was for non dialysis patients)

2

8

1

9

1

10

1

 

Both of these surveys were limited in nature but, in my opinion, underscore the questions that clinical providers need to answer to justify creatinine’s inclusion on a hospital’s critical value list. 

  1. What is the clinical utility for critical creatinine value notification?
  2. What critical cutoff for creatinine would provide the most utility without generating too many unnecessary calls?

 

1: Genzen JR, Tormey CA; Education Committee of the Academy of Clinical

Laboratory Physicians and Scientists. Pathology consultation on reporting of critical values. Am J Clin Pathol. 2011;135:505-13

 

 

2: Wagar EA, Friedberg RC, Souers R, Stankovic AK. Critical values comparison: a College of American Pathologists Q-Probes survey of 163 clinical laboratories. Arch Pathol Lab Med. 2007;131:1769-75)

 

3: Dighe AS, Rao A, Coakley AB, Lewandrowski KB. Analysis of laboratory critical value reporting at a large academic medical center. Am J Clin Pathol.2006;125:758-64

 

 

4: Howanitz PJ, Steindel SJ, Heard NV. Laboratory critical values policies and procedures: a college of American Pathologists Q-Probes Study in 623 institutions. Arch Pathol Lab Med. 2002;126:663-9

 

5: Emancipator K. Critical values: ASCP practice parameter. American Society of Clinical Pathologists. Am J Clin Pathol. 1997;108:247-53.

 

6: Lundberg GD. Critical (panic) value notification: an established laboratory practice policy (parameter). JAMA ;263:709.

 

7: Kost GJ. Critical limits for urgent clinician notification at US medical centers. JAMA 1990;263:704-7

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