medical definitions through an extensive alphabetical listing.

  CAD is known by a number of other names:

  • Autoimmune Hemolytic Anemia (Anaemia)
  • Cold Agglutinin Autoimmune Hemolytic Anemia (Anaemia) (CAIHA)
  • Cold Haemagglutinin Disease (CHD)
  • Coombs Positive Hemolytic Anemia (Anaemia)
  • Primary Chronic Cold Agglutinin Disease


Occurs suddenly. Symptoms or signs that begin and worsen quickly, not chronic.


The term is used to describe the process of red blood cells clumping (agglutinating) in response to the cold-reacting antibodies which are attached to the red cells. The blood clumping could cause the skin to appear blue on the face, legs, ears or other areas of the body.


One is considered anemic when the red blood cells are destroyed faster than the body can replenish them causing the hemoglobin level to drop below the norm of 12 for women and 14 for men. In some countries, the units of measurement are different, and 12.0 becomes 120, and 14.0 becomes 140. Red blood cells distribute the oxygen throughout the body to nourish muscles, tissues, heart, kidneys, lungs, and when there are too few red cells, one may experience loss of energy, fatigue, shortness of breath, dizziness, mental confusion, muscle weakness, and other symptoms of anemia.


Antibodies are a type of protein. The basic structure of a protein is a chain of amino acids. Antibodies can be triggered by and directed at foreign proteins, microorganisms, or toxins. These foreign substances are called antigens. Each antibody binds to and attacks one particular antigen. The production of antibodies is a major function of the immune system and is carried out by a type of white blood cell called a B cell (B lymphocyte). Some antibodies are autoantibodies and home in against our own tissues.


An antigen is any substance that causes your immune system to produce antibodies against it. An antigen may be a foreign substance from the environment or it may be formed within the body, as with bacterial toxins or tissue cells.


Of or relating to an immune response by the body against one of its own tissues, cell, or molecules.

Blood Count

Refers to the number of red blood cells (erythrocytes), white cells (leukocytes), and platelets in a definite volume of blood. The red blood count (RBC) is expressed as the Hemoglobin.

Blood Transfusion

When it becomes necessary to quickly boost the number of red blood cells in your body, due to a very low hemoglobin, a blood transfusion is administered. Washed packed red cells are infused intravenously via a needle, usually in the forearm. It is essential to use a blood warmer to prevent agglutination (clumping) of the transfused blood.


Means severe/existing for a long time as in chronic indigestion.


An ancient defense mechanism that uses 30 proteins in the blood. It is named complement because the system helps antibodies kill invaders. In Cold Agglutinin Disease, complement and antibodies bind to and attack the antigen on red blood cells causing hemolysis and subsequent anemia.


The fraction of blood which is red blood cells, normally about 45%.


From Wikipedia:

Hemoglobin or haemoglobin (frequently abbreviated as Hb) is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. Hemoglobin in vertebrates transports oxygen from the lungs to the rest of the body, such as to the muscles, where it releases the oxygen load.

Hemoglobin is one of the most important “numbers” for those of us with CAD, as it indicates to what degree we are anemic. Typically, a value of about 13 or greater is absolutely fabulous for us, while once we get down to 10, there is cause to become concerned. Below that, we are reaching a more serious level, possibly necessitating a blood transfusion.

In some countries, such as the USA, hemoglobin is quoted as 11.5, whereas in others the equivalent is 115.


Means the destruction/breaking open of red blood cells and the release of hemoglobin into the surrounding fluid. Normally, red cells live for 110-120 days before they are destroyed by the spleen and liver. Some diseases and processes cause premature breakdown of red blood cells, leaving an abnormally small amount of red cells available for transporting oxygen. One such disease is Cold Agglutinin Disease.


Of unknown origin. Primary Cold Agglutinin Disease is idiopathic since there is no known cause and the person is otherwise healthy.


If the Cold Agglutinin condition occurs as the result of some other disease, it is known as Secondary CAD. Generally, curing or arresting the underlying disease will result in resolving the CAD.


The word Titer, is used to describe the concentration of Cold Agglutinin antibodies you have in your blood. A negative titer is less than about 1:32. A person with Cold Agglutinin Disease may have a positive titer of 1:64 or greater and can go as high as 50-100,000. The titer is a measurement obtained after diluting the blood with a salt solution to determine the highest level at which the Cold Agglutinins are no longer detectable. That number is then considered your titer, also known as your antibody load. The greater the quantity of antibodies, the more likely one is affected by the disease.