Imagine you are a Medical Laboratory Scientist (MLS) in a large teaching hospital. After running a routine specimen for a 38 year-old female who was admitted for abdominal pain and weakness, you obtain these lab results:
BUN: 18 (7-20 mg/dl)
Na: 140 (135-145 mmol/L)
K: 1.9 (3.5-5.1 mmol/L)
Cl: 128 (98-107 mmol/L)
CO2: 15 (21-21 mg/dL)
Glucose: 99 (70-99 mg/dL)
Creatinine: 0.78 (0.50-1.30 mg/dL)
Ca: 9.0 (8.5-10.1 mg/dL)
Anion Gap: 2.0 (7-16 mmol/L)
As an MLS, you are alarmed by the three abnormal and critical values that delta from previous results and need to decide what the next step is. Do you release the results as is? Do you ask the provider what they think about the results? Do you ask the nurse for a redraw?
Now before you decide too quickly, let’s take a second look at the values and what they mean in relation to each other. The potassium may catch your eye, telling you that something isn’t right. The fact that it is very low in conjunction with the chloride and carbon dioxide makes you highly suspect a spurious value. Because of your clinical laboratory education, you remember that if drawn improperly, normal saline (containing sodium and chloride) would cause the chloride to increase, potassium to decrease, thus causing a decrease in the anion gap. The CO2 would also be falsely decreased with IV saline. Because of your clinical laboratory training, you know that the IV contaminated specimen compromises the care of the patient, causing anything from unnecessary or delayed treatment and costs to severe harm and fatality. In order to help clinicians and protect patients, you as the laboratorian will decide to cancel the specimen and request a redraw, after communicating with the appropriate clinical staff.
While this is only one example, there are many pre-analytical variables that affect laboratory results. Spurious values can be caused by mislabeled specimens, infusions, blood transfusions, wrong tube pour-over, incorrect order of draw, among other technical errors. Although there are delta checks put into place, the laboratorian’s clinical judgment and knowledge is crucial to be able to differentiate an actual valid result from a spurious one. It is up to the clinical laboratorian to not only identify these situations, but also investigate to determine the cause and communicate with clinical staff as appropriate, making this role vital to patient safety and care. Medical laboratory professionals are essential members of the healthcare team.
Submitted by Jelinda Easo '19