Sulfhemoglobinemia

Sulfhemoglobinemia is a rare blood condition that occurs when a sulfur atom is incorporated into the hemoglobin molecule. When hydrogen sulfide (H2S) (or sulfide ions) and ferric ions combine in the blood, the blood is incapable of carrying oxygen.

This can be caused by taking medications that contain sulfonamides under certain conditions (i.e.: overdosing of sumatriptan). Drugs associated with sulfhemoglobinemia include acetanilid, phenacetin, nitrates, trinitrotoluene and sulfur compounds (mainly sulphonamides). Another possible cause is occupational exposure to sulfur compounds. The condition generally resolves itself with erthryocyte (red blood cell) turnover, although blood transfusions can be necessary in extreme cases. The pigment is a greenish derivative of hemoglobin which cannot be converted back to normal, functional hemoglobin. It causes cyanosis even at low blood levels.

Symptoms include a blueish or greenish discoloration of the blood, skin, and mucous membranes, even though a blood count test may not show any abnormalities in the blood.

On June 11, 2007, Canadian surgeons Dr. Stephan Schwarz and Dr. Alana Flexman presented an unusual case in The Lancet. A 42-year-old male patient was brought into Vancouver's St. Paul's Hospital after falling asleep in a sitting position. When doctors drew the man's blood to relieve pressure from his legs, the blood was green. A sample of the blood was immediately sent to a lab. In this case, sulfhemoglobinaemia was likely caused by the patient taking higher-than-prescribed doses of sumatriptan.