5 Responding to Critical Laboratory Findings

Understand the urgency

A Critical result may signal an immediate threat to life, but the laboratory number is not the whole clinical picture. A result’s urgency depends on the patient’s current condition as well as the finding itself. Symptoms or instability can make a result more urgent than the number alone suggests.

Follow the facility’s critical-value policy. Thresholds and reporting timelines can vary by laboratory, patient population, and care setting. Do not delay urgent care while trying to confirm whether a value meets a memorized cutoff.

Respond in a reliable sequence

Use a consistent sequence to respond:

1. Verify and clarify. Confirm the patient’s identity, test, result, units, and any laboratory comment, such as a hemolyzed specimen. Use read-back for a verbal result according to policy.

2. Assess immediately. Check airway, breathing, circulation, vital signs, mental status, symptoms, and relevant focused findings. Look at the patient, not only the result.

3. Escalate without delay. Notify the responsible clinician through the required escalation pathway. If the patient is unstable or deteriorating, activate the rapid-response or emergency system rather than waiting for a callback.

4. Take safe interim measures. Apply monitoring and precautions appropriate to the finding. Carry out standing protocols or orders within your role; do not independently initiate treatment outside policy or scope.

5. Close the loop. Confirm that the right clinician received the result and that a plan was made. Document the result, notification and read-back, assessment, actions, response, and follow-up plan.

A result is not safely managed merely because it appeared in the chart. Closed-loop communication means that the result is received, acknowledged, and acted upon—not merely sent.

Respond to critical potassium

A laboratory reports potassium of $6.7\,\text{mEq/L}$ for a patient with acute kidney injury who reports weakness; the monitor shows new peaked T waves, and the specimen may be hemolyzed. Assess immediately, activate urgent escalation, maintain cardiac monitoring, and obtain or facilitate a 12-lead ECG according to protocol. Report both the result and the ECG changes.

A repeat specimen may be needed to evaluate possible hemolysis, but do not wait for the repeat result before escalating or protecting the patient. Significant hyperkalemia can cause dangerous dysrhythmias, and ECG changes make the situation especially urgent.

Treat severe low glucose safely

A patient who is NPO becomes confused and diaphoretic, with a point-of-care glucose of $42\,\text{mg/dL}$. Assess responsiveness and airway, summon help as needed, and follow the facility’s severe-hypoglycemia protocol. Because confusion and NPO status make swallowing unsafe, do not give food, drink, or oral glucose. Use the ordered or protocol-approved nonoral treatment, then recheck glucose at the specified interval and continue monitoring for recurrence. Severe hypoglycemia with altered mental status is an emergency.

Respond to severe sodium abnormalities

A patient with sodium of $118\,\text{mEq/L}$ develops worsening confusion and a seizure. Activate the emergency response, protect the patient from injury, and support airway and breathing while help arrives. Notify the responsible clinician immediately and report the sodium result, seizure, and change in mental status.

Do not leave the patient unattended or attempt to correct sodium independently. Treatment and the rate of correction require a clinical plan and close monitoring. Severe sodium abnormalities can cause confusion and seizures.

Assess critical hemoglobin with symptoms

A laboratory flags a hemoglobin of $6.4\,\text{g/dL}$ as critical, and the patient is newly short of breath and tachycardic. Assess airway, breathing, circulation, vital signs, oxygenation, mental status, and signs of active bleeding. Escalate promptly and report the symptoms along with the result. Maintain appropriate monitoring and prepare for ordered follow-up, which may include additional testing or blood products.

Do not assume that a transfusion decision follows one universal hemoglobin cutoff; the clinician considers symptoms, context, and local policy. If the patient becomes unstable, activate the emergency response.

Escalate deterioration with a positive culture

A patient being treated for infection has a newly positive blood culture and is febrile, tachycardic, hypotensive, and newly confused. Treat this as a possible sepsis emergency: assess immediately, alert the responsible clinician, and activate the facility’s sepsis or rapid-response pathway as indicated. Report the culture result together with the vital signs and mental-status change.

Follow facility procedures for monitoring, cultures, and time-sensitive treatment. Do not wait for a routine round or for every test result before escalating. Patients who may have sepsis require immediate evaluation and treatment.

Continue escalation until a plan is made

If a clinician does not acknowledge a reported critical result and the patient’s condition is worsening, do not treat a message or voicemail as completed escalation. Continue through the facility’s escalation chain until a qualified clinician acknowledges the result and a plan is established. If the patient is deteriorating, activate the rapid-response or emergency system now.

Reassess the patient, continue appropriate safety measures, and document each contact, response, and action. Follow through until the result has been acknowledged and acted on.

• Hyponatremia