For a plasma lithium level measured at 14.0 mmol/L, what action should be taken?

In the case of a plasma lithium level measured at 14.0 mmol/L, the action of calling for a new specimen is appropriate due to the significantly elevated value. Lithium levels exceeding the therapeutic range (typically 0.6 to 1.2 mmol/L for most patients) can indicate toxicity. At 14.0 mmol/L, this result suggests severe toxicity, which can be life-threatening and requires immediate medical attention.

Verifying with a new specimen eliminates the risk of potential preanalytical errors that could have contributed to this aberrant result, such as issues with the original sample (e.g., contamination, improper storage, or the influence of hemolysis). This action is critical given the high stakes involved when dealing with lithium levels; an incorrect result could lead to unnecessary alarms or, conversely, a delay in needed interventions.

Obtaining a fresh sample ensures accuracy and validity, allowing for a correct assessment of the patient's condition. Therefore, calling for a new specimen is justified, as it prioritizes patient safety and accurate clinical decision-making.