Critical Care Medicine-Renal, Electrolyte and Acid Base Disorders>>>>>Oliguria and Polyuria
Question 1#

A previously healthy 18-year-old woman presents to the emergency department 4 hours ago with headache and photophobia. Her parents state that her symptoms began as a mild fever and headache, and today, she appears to be a bit confused and has been urinating a lot. On physical examination, she is alert and oriented but slow to answer questions. There are no focal neurological signs. Her labs reveal elevated leukocytosis and hypernatremia. Blood cultures were sent.

What is the next BEST step in management?

A. Start broad-spectrum antibiotics
B. Obtain urine sodium, chloride, creatinine, and osmolality
C. Obtain spinal fluid sample
D. Obtain CT scan of head

Correct Answer is A


Correct Answer: A

Central diabetes insipidus (DI) is a rare complication of bacterial meningitis. The presence of polyuria and hypernatremia is concerning for the development of DI in this patient. While it is important to obtain urine electrolytes and osmolality (Answer C) to confirm the diagnosis of DI, the most concerning issue here is the potential for bacterial meningitis in this patient. Therefore, prompt diagnosis and treatment are needed to prevent morbidity and mortality. According to the 2004 Infectious Diseases Society of America guidelines, a CT scan of head is indicated when a patient is immunosuppressed, has new onset of seizure, a history of an intracranial mass lesion, altered mental status, or focal neurological deficit. However, this patient does not have any of these features, making choice D incorrect.

Obtaining a sample of spinal fluid is essential for diagnosis of meningitis. However, in this case, there was a delay in antibiotics initiation since the patient has been in the emergency department for 4 hours before consultation with no antibiotics initiated. Delay in antibiotic administration is associated with worse outcomes in patients with bacterial meningitis. Retrospective data suggest a 10% increase of in-hospital mortality and risk for unfavorable outcomes with each hour of delay. Thus, antibiotic administration takes precedence in this patient.

Tunkel AR. Clinical Features and Diagnosis of Acute Bacterial Meningitis in Adults. Uptodate. 2018.

Bichet DG. Evaluation of Patients with Polyuria. Uptodate. 2019.

Bodilsen J, Dalager-Pedersen M, Schonheyder HC, Nielsen H. Time to antibiotic therapy and outcome in bacterial meningitis: a Danish population-based cohort study. BMC Infectious Diseases. 2016;16:392. Epub 2016/08/11. doi:10.1186/s12879 to 016 to 1711-z.