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Absence of symptoms and acidosis in potentially lethal methanol poisoning
Absence of S y m p t o m s and Acidosis in Potentially Lethal Methanol Poisoning To the Editor: The estimated lethal level for methanol is 80 mg/dL.¢ Gonda et al, who reviewed previous reports of methanol ingestion, did not find any patients who had markedly increased methanol levels and at the same time were asymptomatic. 4 One of the reasons for the absence of acidosis in patients who have ingested methanol is the concomitant presence of ethanol in blood. An ethanol level of 100 mg/dL may be required to saturate the alcohol dehydrogenase enzyme system. ~ Our patient had an ethanol concentration in blood that was approximately one tenth of this. H u m a n susceptibility to methanol may be dependent on the functioning of the folate pathway. 3 There was no obvious clinical or hematologic evidence of folate deficiency in our patient. Our case demonstrates that in certain fortunate individuals, the severe clinical consequences of methanol ingestion may not occur for reasons that require further study.
The usual outcome of methanol poisoning is metabolic acidosis and, in some cases, blindness. 1 The laboratory evidence for methanol intoxication is the presence of an increased anion gap type acidosis, the presence of an osmolar gap, and increased methanol levels in blood. ~. The symptoms of methanol poisoning may be delayed 11 to 18 hours, and this latent period is thought to correspond to the time required for methanol to be metabolized to formaldehyde and formic acid. 3 We present the case of a patient with approximately three and a half times the estimated lethal level for methanol. The patient was completely asymptomatic 24 hours after ingestion, and did not develop metabolic acidosis at any time during his hospital course. The patient, a 17-year-old man "who had a desire to be blind," ingested about 400 mL of methanol and arrived at the hospital about 24 hours later. He appeared healthy and was afebrile. Pulse was 100/min; blood pressure, 105/70 m m Hg; and respirations, 16/min. Findings on physical examination were entirely normal, including results of detailed eye examination. Routine laboratory studies yielded the following values: sodium, 145 mmol/L; potassium, 3.8 mmol/L; chloride, 107 mmol/L; total CO2, 27 mmol/L; urea nitrogen, 15 mg/dL; and creatinine, 1.0 mg/dL. Serum osmolality was 392 m O s m / k g H20. Arterial blood pH was 7.40; PCO2, 45; and PO2, 103. Hemoglobin, leukocyte and platelet counts were normal. Chest film and ECG were within normal limits. Serum methanol was 273 mg/dL; ethanol was 11 mg/dL; and isopropanol and ethylene glycol were not detected. Oral ethanol treatment and hemodialysis were started and continued for ten hours. The patient had an uneventful recovery. Serial measurements of electrolytes, pH, methanol, and ethanol levels in the patient are shown (Table).
Amin A Nanji, MD, FRCP(C) Department of Pathology Vancouver General Hospital and University of British Columbia Vancouver, British Columbia, Canada 1. Bennett IL, Carey FH, Mitchell GL, et al: Acute methyl alcohol poisoning: A review based on experiences in an outbreak of 323 cases. Medicine 1952;32:431-463. 2. Becker CE: Acute methanol poisoning. West J Med 1981;135: 122-128. 3. McMartin KE, Ambre JJ, Tephly TR: Methanol poisoning in human subject's. Am J Med 1980;68'414-418. 4. Gonda A, Gault H, Churchill D, et al: Hemodialysis for methanol intoxication. Am J Med 1978;64:749-758.
TABLE. Serial levels of serum electrolytes, osmolality, blood pH, methanol and ethanol levels in the patient
Hours After Admission
Na
K
CI
TCO2
Osm/kg H20
pH
0 5 11 24 28 30 36 48
145 141 137 139 136 133 140 139
3.8 4.1 4.0 4,1 3.6 3.4 3,5 3.7
107 105 103 101 101 101 100 100
27 24 25 26 25 26 25 28
392
7.40 7.40 7,39
336 319 318 287 286
7.36 7,38 7.40
Methanol mg/dL
Ethanol mg/dl
273 t 80 190 t 14 I08 99 56, 26
11 ND 20 19 ND 4 ND
Treatment of Exposure to Chemical Personal Protection Agents To the Editor: "Tear gas" has been used for many years by law enforcement agencies throughout the United States. With more ci:13:6 June 1984
Annals of
vilians carryin~ chemical agents for personal protection, the emergency physician will see an increase in the number of
EmergencyMedicine
487/123
The usual outcome of methanol poisoning is metabolic acidosis and, in some cases, blindness. 1 The laboratory evidence for methanol intoxication is the presence of an increased anion gap type acidosis, the presence of an osmolar gap, and increased methanol levels in blood. ~. The symptoms of methanol poisoning may be delayed 11 to 18 hours, and this latent period is thought to correspond to the time required for methanol to be metabolized to formaldehyde and formic acid. 3 We present the case of a patient with approximately three and a half times the estimated lethal level for methanol. The patient was completely asymptomatic 24 hours after ingestion, and did not develop metabolic acidosis at any time during his hospital course. The patient, a 17-year-old man "who had a desire to be blind," ingested about 400 mL of methanol and arrived at the hospital about 24 hours later. He appeared healthy and was afebrile. Pulse was 100/min; blood pressure, 105/70 m m Hg; and respirations, 16/min. Findings on physical examination were entirely normal, including results of detailed eye examination. Routine laboratory studies yielded the following values: sodium, 145 mmol/L; potassium, 3.8 mmol/L; chloride, 107 mmol/L; total CO2, 27 mmol/L; urea nitrogen, 15 mg/dL; and creatinine, 1.0 mg/dL. Serum osmolality was 392 m O s m / k g H20. Arterial blood pH was 7.40; PCO2, 45; and PO2, 103. Hemoglobin, leukocyte and platelet counts were normal. Chest film and ECG were within normal limits. Serum methanol was 273 mg/dL; ethanol was 11 mg/dL; and isopropanol and ethylene glycol were not detected. Oral ethanol treatment and hemodialysis were started and continued for ten hours. The patient had an uneventful recovery. Serial measurements of electrolytes, pH, methanol, and ethanol levels in the patient are shown (Table).
Amin A Nanji, MD, FRCP(C) Department of Pathology Vancouver General Hospital and University of British Columbia Vancouver, British Columbia, Canada 1. Bennett IL, Carey FH, Mitchell GL, et al: Acute methyl alcohol poisoning: A review based on experiences in an outbreak of 323 cases. Medicine 1952;32:431-463. 2. Becker CE: Acute methanol poisoning. West J Med 1981;135: 122-128. 3. McMartin KE, Ambre JJ, Tephly TR: Methanol poisoning in human subject's. Am J Med 1980;68'414-418. 4. Gonda A, Gault H, Churchill D, et al: Hemodialysis for methanol intoxication. Am J Med 1978;64:749-758.
TABLE. Serial levels of serum electrolytes, osmolality, blood pH, methanol and ethanol levels in the patient
Hours After Admission
Na
K
CI
TCO2
Osm/kg H20
pH
0 5 11 24 28 30 36 48
145 141 137 139 136 133 140 139
3.8 4.1 4.0 4,1 3.6 3.4 3,5 3.7
107 105 103 101 101 101 100 100
27 24 25 26 25 26 25 28
392
7.40 7.40 7,39
336 319 318 287 286
7.36 7,38 7.40
Methanol mg/dL
Ethanol mg/dl
273 t 80 190 t 14 I08 99 56, 26
11 ND 20 19 ND 4 ND
Treatment of Exposure to Chemical Personal Protection Agents To the Editor: "Tear gas" has been used for many years by law enforcement agencies throughout the United States. With more ci:13:6 June 1984
Annals of
vilians carryin~ chemical agents for personal protection, the emergency physician will see an increase in the number of
EmergencyMedicine
487/123