Which labs and diagnostics should be ordered for thermal injuries?

• A. CBC, BMP, liver enzymes, and abdominal ultrasound
• B. MRI of the affected region
• C. ABG with carboxyhemoglobin level, CBC, BMP, CXR
• D. Serum electrolytes alone

Answer: (C)

In thermal injuries the immediate goal is to assess airway, breathing, circulation, and the extent of inhalation injury and systemic impact. An arterial blood gas with carboxyhemoglobin level is essential because it provides oxygenation status and detects carbon monoxide poisoning, which can cause tissue hypoxia even when PaO2 looks normal. Including carboxyhemoglobin helps you gauge risk and decide on treatments such as high-flow oxygen.

A complete blood count and basic metabolic panel give rapid insight into the patient’s overall physiology: the CBC baseline helps monitor infection risk and hematologic status, while the BMP evaluates electrolytes and kidney function—both critical for guiding fluid resuscitation and detecting electrolyte disturbances that can accompany burn injury.

A chest radiograph screens for inhalation injury and early pulmonary edema, informing airway management and ventilatory support decisions. Together, these tests cover gas exchange, CO exposure, organ function, and chest involvement in burn patients.

Other options miss key aspects of the initial assessment. Liver enzymes and abdominal ultrasound aren’t routinely needed unless there’s concern for abdominal trauma. MRI isn’t practical or first-line in the acute burn setting. Serum electrolytes alone don’t provide the full picture of respiratory status, acid-base balance, or chest injury.