Sulfhemoglobinemia (or sulfhaemoglobinaemia) is a rare condition in which there is excess sulfhemoglobin (SulfHb) in the blood. 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.
It 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.
If you find this to be abstract, here the story of a 42-year-old white Canadian, who developed this rare condition.
He had developed nerve damage due to restricted blood flow in his lower legs after falling asleep in a sitting position. He was a smoker and his medical history included chronic shoulder pain and migraine headaches. He was taking a number of prescription medications, including Sumatriptan for the migraines.
To save his lower legs from the damage they decided to do fasciotomies, where the tissue is cut to relieve pressure. They performed a battery of emergency tests and his blood pressure was normal. He did have high Creatine Kinase concentration and a rapid heartbeat. Creatine Kinase is an important enzyme in tissue repair and high levels usually mean damage to muscle while very low levels might mean an alcoholic liver disease or rheumatoid arthritis.
Still, nothing critical, his toxicology screen was negative and surgery was approved. In the operating room is when things got strange. When doctors tried to place a catheter in the radial artery, his blood came out … green.
Off to the lab, his blood went.
There’s a condition called cyanosis when the blood cannot bind oxygen and this means the blood is also not properly delivering oxygen to tissues. It creates a blue color on the skin.
But the classic case of cyanosis results from deoxyhemoglobin, a lack of oxygen in the blood. Less often it is caused by high methemoglobin which differs from normal hemoglobin in that the oxygen-carrying ferrous iron in the heme groups has been oxidized to the ferric iron. His methemoglobin concentration was normal. Plus, cyanosis caused by methemoglobinemia usually results in brown- or chocolate-colored blood that does not become red when exposed to oxygen. It isn’t green.
They turned to the rare sulfhemoglobinemia, rather than classic cyanosis, as the cause of the green-black blood. Sulfhemoglobinemia happens when a sulfur atom is incorporated into the hemoglobin molecule, and it can be caused by medications, including sulfonamides, which were present in the sumatriptan the patient had been taking for migraine headaches.
Did the sumatriptan create the green blood?
Said Flexman, “The triptans used to treat a migraine have never been reported to cause sulfhemoglobinemia. I would also like to stress that we can in no way prove that sumatriptan was the cause of his sulfhemoglobinemia. In our case, sumatriptan was a possibility because it contains a sulfonamide group and sulfonamides have been reported to cause sulfhemoglobinemia.”
It’s an extremely rare condition that doesn’t occur very often. There aren’t lots of information on the internet about this disease, so if you have some of the symptoms described above, we strongly advise you to visit the nearest hospitals.