History and physical exam and simple math go a long way in developing a diagnostic differential: a case of methanol poisoning

INTRODUCTION: Patients who present to the ER with altered mental status due to toxic ingestion or attempted suicide are difficult to treat because of unknown social and clinical factors. We present a case of methanol ingestion that highlights the importance of obtaining a good history and physical exam.CASE PRESENTATION: A 46-year-old male was brought to the ER with complaints of altered mental status, abdominal pain, and alcohol intoxication. The family reported that the patient had a history of alcohol dependence but had been sober for 2 years. However, recently, he developed severe depression and had been consuming large quantities of alcohol. The family also admitted he had possibly consumed household substances for their alcohol content. On examination, the patient was in moderate distress and had altered mental status. Except for severe right upper quadrant tenderness, the physical exam was unremarkable. Laboratory results showed WBC 10,200/dL. Electrolytes were sodium 139, potassium 4, chloride 110, bicarbonate 16, creatinine 1.4, total bilirubin 0.4, aspartate transaminase 64, alanine transaminase 56. Serum osmolality was 381. Ethanol level was less than 10 mg/dL. His calculated anion gap was 13, ABG pH 7.27, and calculated serum osmolality was 295, indicating anion gap metabolic acidosis with an increased osmolar gap of 86. As a precaution, the patient was started on intravenous fomepizole. At that time, additional questions were asked of the patient which resulted in admission of ingestion of a household product, but the specifics were not known. Methanol and ethylene glycol levels were ordered. Isopropyl alcohol, ethylene glycol, salicylate and acetaminophen levels were found to be within normal limits. The patient's methanol and acetone levels were 154 mg/dL and 80mg/dL, respectively. As a result, emergent hemodialysis was initiated and within 24 hours, methanol levels were less than 10mg/dL.DISCUSSION: Methanol poisoning is one of the most common types of alcohol related toxicities and can mimic ethanol intoxication because it causes central nervous depression. In 2010, there were 719 possible methanol exposures (excluding automotive products and cleaning agents) and 12 deaths.CONCLUSIONS: A detailed history, recognition of abnormal lab parameters, application of simple calculations can narrow down the differential diagnosis in cases of possible overdose or suicide attempt. In this case, initial clinical exam and history increased suspicion of toxic ingestion. Appropriate lab tests were ordered based on the possible substances and timely identification and intervention with fomepizole and emergent dialysis played a significant role in preventing complications related to methanol toxicity including permanent loss of vision, multi-system organ failure, and subsequent death.1) AAPCC (American Association of poison control centers) 2010 Annual Report of the NPDS (National Poison Data System)DISCLOSURE: The following authors have nothing to disclose: Jason Lambrecht, Madhu Kalyan Pendurthi, Vijaya Gogineni, Thomas Rayl, Anna MaioNo Product/Research Disclosure InformationCreighton University Medical Center, Omaha, NE. Language: en