Sulfhemoglobincontaining

Sulfhemoglobin-containing refers to blood in which a portion of hemoglobin molecules have been chemically altered by the incorporation of a sulfur atom, creating sulfhemoglobin. Sulfhemoglobin is an abnormal form of hemoglobin that binds oxygen poorly and is irreversibly formed; once sulfhemoglobin is present, normal oxygen transport can be impaired until affected red blood cells are replaced.

Formation occurs after exposure to sulfur-containing compounds, including certain sulfonamide antibiotics (for example sulfamethoxazole, sulfadiazine), other drugs, industrial chemicals and dyes, and some hydrogen sulfide sources. The reaction is not repaired by reducing agents and the sulfhemoglobin fraction increases with continued exposure.

Clinically, patients may develop persistent cyanosis that does not improve with supplemental oxygen. Some individuals are asymptomatic. Diagnosis relies on specialized co-oximetry or spectrophotometry that can quantify sulfhemoglobin and distinguish it from other dyshemoglobins; standard pulse oximetry may show reduced readings, but ABG with co-oximetry is definitive. The total hemoglobin concentration is often normal.

Management centers on removing the offending agent; there is no specific antidote. Most cases resolve slowly as red blood cells turnover, with new erythrocytes lacking sulfhemoglobin replacing older ones over weeks to months. In severe or ongoing exposure, the sulfhemoglobin fraction may persist longer. Methylene blue is ineffective for sulfhemoglobinemia and should not be used to treat it.