A 30 year old female with a history of type 1 diabetes and past hospitalizations for diabetic ketoacidosis presents via EMS for altered mental status. History is limited as patient is altered and not answering questions appropriately. Vitals include Temp 100.4F, HR 116, BP 102/70, RR 30, SpO2 98% on room air. Exam shows an ill-appearing female with Kussmaul respirations and a non-focal neurologic exam. Labs are notable for 20K WBCs and serum glucose of 400. A lumbar puncture is performed to assess for meningitis. For this patient, which of the following CSF glucose values is within normal limits?
A: 60 mg/dL
B: 100 mg/dL
C: 260 mg/dL
D: 400 mg/dL
Answer: 260 mg/dL
This patient is presenting with signs and symptoms of diabetic ketoacidosis. While it is critical for the emergency physician to treat the hyperglycemia with volume resuscitation and insulin, it is also paramount to investigate for underlying causes such as infection. The glucose level in CSF is proportional to serum glucose values and should correspond to approximately 60-70% of serum glucose values. Thus, a CSF glucose value of 60 or 100 mg/dL in this patient is lower than expected and concerning for bacterial CNS infection. Higher than expected CSF glucose levels are non-specific and generally do not exceed 300 mg/dL.
Lillian A. Mundt; Kristy Shanahan (2010). Graff’s Textbook of Routine Urinalysis and Body Fluids. Lippincott Williams & Wilkins. p. 237. ISBN 978-1582558752.
Seehusen DA, Reeves MM, Fomin DA (September 2003). “Cerebrospinal fluid analysis”. Am Fam Physician. 68 (6): 1103–8. PMID 14524396