The Kidd (Jk) blood group is a blood group containing Jk antigens. Antigens are substances that can cause immune responses if the body does not recognize them. These immune responses mainly happen during blood transfusions and pregnancy when there is blood incompatibility. Blood incompatibility means that one person has antigens in the blood that the other person’s body does not recognize. As a result, antibodies attack these antigens. In blood transfusions, this can cause a hemolytic transfusion reaction (HTR). HTR harms the recipient's red blood cells.
Symptoms of HTR include fever, chills, back pain, or blood in the urine during or after the transfusion. Mild symptoms can be treated with acetaminophen or fluids for hydration. More severe complications from HTR include kidney failure, lung problems, and anemia (low red blood cell count).
In pregnancy, blood incompatibility can cause hemolytic disease of the newborn (HDN). Symptoms of HDN during pregnancy include yellow amniotic fluid, enlarged organs in the fetus, and extra fluid in the fetus. After birth, symptoms may include pale or yellow skin (jaundice), enlarged organs, or general swelling of the baby. A doctor can detect HDN during pregnancy with a Coombs test. The direct Coombs test finds antibodies that have already attached to the baby's red blood cells. The indirect Coombs test finds these antibodies before they attack the baby's red blood cells. HDN caused by the Kidd blood group is usually milder than HDN caused by other blood groups. Treatment of HDN may involve methods to help the baby breathe or blood transfusions to give the baby more red blood cells.
Besides problems with blood compatibility, individuals who do not have Jk antigens in their red blood cells may produce less concentrated urine. No other health issues have been linked to a lack of Jk antigens.
Description Last Updated: Sep 30, 2017