Sulfhemoglobinemia

Sulfhemoglobinemia 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.

Sulfhemoglobinemia
Specialty	Hematology
Symptoms	Cyanosis, urinary tract infection and chronic constipation
Complications	Hypoxemia, methemoglobinemia, and hypoxia
Duration	100-120 days (lifespan of red blood cells)
Causes	Sulfur medications such as phenacetin, metoclopramide, dapsone, phenzopyridine, and trimethoprim-sulfamethoxazole; hydrogen-sulfide-producing intestinal bacteria, such as Morganella morganii
Risk factors	Pulmonary arteriovenous malformation
Prevention	Avoidance of sulfur-containing compounds including drugs
Treatment	Blood transfusions

It is a rare blood condition in which the β-pyrrole ring of the hemoglobin molecule has the ability to bind irreversibly to any substance containing a sulfur atom.^[1][2] When hydrogen sulfide (H₂S) (or sulfide ions) and ferrous ions combine in the heme of hemoglobin, the blood is thus incapable of transporting oxygen to the tissues.

Presentation

Symptoms include a blueish or greenish coloration of the blood (cyanosis), skin, and mucous membranes, even though a blood count test may not show any abnormalities in the blood. This discoloration is caused by greater than 5 grams per cent of deoxyhemoglobin, or 1.5 grams per cent of methemoglobin, or 0.5 grams per cent of sulfhemoglobin, all serious medical abnormalities.^{[citation needed]}

Causes

Sulfhemoglobinemia is usually drug induced, with drugs associated with it including sulphonamides, such as sulfasalazine or sumatriptan. Another possible cause is occupational exposure to sulfur compounds.^{[citation needed]}

It can also be caused by phenazopyridine.^[3]

Diagnosis

Treatment

The condition generally resolves itself with erythrocyte (red blood cell) turnover, although blood transfusions can be necessary in extreme cases.^{[citation needed]}