Methemoglobinemia in a Case of Paint Thinner Intoxication, Treated Successfully with Vitamin C

Methemoglobin (MetHb) is an oxidized form of hemoglobin. It is a poor transporter of oxygen and is unable to deliver oxygen to the tissue. Globally, drug & toxin induced methemoglobinemia is more common as compared with the congenital form. Methemoglobinemia caused by paint thinner intoxication is rare. Methylene blue is well established as the first-line therapy for severe methemoglobinemia.

A 25-year old man was brought to the Emergency Department after accidental consumption of paint thinner. On clinical examination, he had cyanosis and there were discrepancies in his pulse oximetry and arterial blood gas (ABG) analysis results. With this clue and supporting laboratory investigations, the diagnosis of toxin-induced methemoglobinemia was made. Due to the unavailability of methylene blue, alternative treatment with high-dose vitamin C was attempted, to which the patient responded. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The role of vitamin C in the treatment of methemoglobinemia has not been well established, with only a few published case reports. This patient had severe methemoglobinemia, with MetHb of 46.4%, which responded dramatically to vitamin C therapy, with no side effects. This case shows that high-dose vitamin C is safe and has the potential to be an effective alternative for the treatment of severe methemoglobinemia. In the presence of cyanosis, mismatch of pulse-oximetry and ABG-analysis are the key for the physician to suspect methemoglobinemia.