Diagnostic Dilemma in a Case of Lyme Borreliosis Presenting as Severe Anion Gap Metabolic Acidosis: A Case Report.

BACKGROUND Lyme disease is a common tickborne disease with a common presentation. Untreated Lyme disease can affect other organs. This can lead to anion gap metabolic acidosis through severe renal failure. Unlike anion gap metabolic acidosis, osmolar gap can be caused by ingestion of ethanol, toxic alcohols, solvents, and salicylates. Therefore, a presentation with osmolar gap and anion gap metabolic acidosis yields a variety of differential diagnoses. CASE REPORT A 72-year-old man presented after being found down. There were few historical cues, and workup was negative for seizures or any acute cerebrovascular incident. Laboratory results were revealing of severe anion gap acidosis with osmolar gap. During clinical decision making and diagnostic dilemma, toxidrome syndromes for potential ingestions and inhalations were sought in addition to thorough workup, which expanded to include infectious etiologies. This patient's presentation was unique: Lyme disease in the setting of severe anion gap metabolic acidosis with an osmolar gap. CONCLUSIONS The outcome of critically ill patients can be determined by the clinician's method to address the diagnostic dilemma and quality of supportive care. Critically ill patient outcomes can be subject to the clinician's method to address a diagnostic quandary. This unique case poses an important reminder for clinicians to maintain their standard methodologies of critical thinking amidst the noise of distracting medical information.