Ionized Calcium (iCa) as an Example

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The page below is a sample from the LabCE course Laboratory Effectiveness: Clinical Laboratory Utilization (retired 6/6/2018). Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Ionized Calcium (iCa) as an Example

Let's consider one test of limited value and how a UM team might approach the problem of over-utilization. iCa is a useful test in the workup of patients with calcium disorders. However it is sometimes ordered more often than is necessary. iCa tends to run low in patients who are very ill. A Cochrane Review stated that medical evidence does not support replacing calcium in critically ill patients unless the person has some specific calcium-related disorder. So when an internist sees low iCa on a patient report, the internist will often infuse the patient with calcium gluconate. This will cause the patient’s iCa level to go up slightly, which then perpetuates the cycle of testing and medicating unnecessarily. iCa levels would have gone up anyway due to the fact that the more measurements one does, the closer those measurements tend to be towards the mean.
A UM team can tackle this problem. First, cite appropriate literature such as the Cochrane recommendation and evidence-based practice/evidence-based medicine papers on the subject. It is important to point out that the iCa test itself is not that expensive. However, the downstream care is expensive. Preparing and infusing unnecessary calcium gluconate is a burden and cost on the pharmacy while retesting taxes the phlebotomy team and slight but insignificant changes may call for unneeded physician reviews. The patient will be inconvenienced with additional draws, etc. There are reports of inpatients who have had over 100 blood draws for iCa, which actually necessitated a blood transfusion. All of these downstream factors need to be pointed out when the UM team makes its case to the medical staff. More testing does not always provide more information. Over-testing, or using the wrong test, or testing too often can lead to unnecessary downstream procedures and workups for patients. In addition, tests of limited value can often cause patient anxiety and confusion rather than providing help for the patient.
Once the UM team sells clinical departments on the science and logic of performing fewer iCa tests, they can then begin discussing plans to curb ordering habits.
Ideas that some institutions have explored include:
  • Institute a voluntary reflexive testing algorithm whereby clinicians can order an iCa only if the total calcium is less than 8 mg/dL.
  • Use the electronic medical record (EMR) to alert clinicians when another iCa is ordered within a specific time frame of the last order (perhaps no more than one iCa is allowed per 48 hours).
  • Give a grand-rounds or other seminar on the topic to educate the internists on the problem. Clinician turnover is common; education and re-education needs to be on-going.
  • Track progress. Be able to show clinicians that with improved utilization the diagnosis of hypocalcemia in inpatients will not increase (they should actually decrease) as well as showing that the number of cases of seizures and tetany (symptoms of hypocalcemia) aren't increasing.
  • Take iCa off of any panels so it can only be ordered individually.