A 17 year-old patient presents to the emergency department with agitation and hallucinations, and has one seizure. He admits to using "some drugs" but does not know what they were. Which diagnostic study will be of most help in managing this patient?

A 17 year-old patient presents to the emergency department with agitation and hallucinations, and has one seizure. He admits to using "some drugs" but does not know what they were. Which diagnostic study will be of most help in managing this patient?

• A. Urine drug screen
• B. Serum CK
• C. Electroencephalogram
• D. CT head

Answer: (B)

The key idea is recognizing that the most immediate danger in this scenario is muscle injury from agitation and a recent seizure, which can progress to rhabdomyolysis and acute kidney injury. Serum creatine kinase (CK) directly measures the extent of muscle breakdown. A high CK level signals rhabdomyolysis and drives the urgent management steps, especially aggressive IV fluid resuscitation to protect the kidneys and to monitor for electrolyte disturbances like hyperkalemia. CK levels help gauge severity and guide ongoing treatment, including whether additional interventions (such as urine alkalinization) might be needed. Urine drug screens can be informative for identifying substances, but their results are not rapidly actionable and don’t directly address the immediate risks from muscle injury. Electroencephalography isn’t a priority unless there are ongoing seizures or altered mental status needing electrographic confirmation. A CT head is generally reserved for focal neurological deficits, head trauma, or altered consciousness with suspicion of intracranial pathology, and it wouldn’t typically change the initial stabilization and rhabdomyolysis management in this specific presentation.

The key idea is recognizing that the most immediate danger in this scenario is muscle injury from agitation and a recent seizure, which can progress to rhabdomyolysis and acute kidney injury. Serum creatine kinase (CK) directly measures the extent of muscle breakdown. A high CK level signals rhabdomyolysis and drives the urgent management steps, especially aggressive IV fluid resuscitation to protect the kidneys and to monitor for electrolyte disturbances like hyperkalemia. CK levels help gauge severity and guide ongoing treatment, including whether additional interventions (such as urine alkalinization) might be needed.

Urine drug screens can be informative for identifying substances, but their results are not rapidly actionable and don’t directly address the immediate risks from muscle injury. Electroencephalography isn’t a priority unless there are ongoing seizures or altered mental status needing electrographic confirmation. A CT head is generally reserved for focal neurological deficits, head trauma, or altered consciousness with suspicion of intracranial pathology, and it wouldn’t typically change the initial stabilization and rhabdomyolysis management in this specific presentation.