Paroxsymal Cold Hemoglobinuria (PCH)

What is PCH?

        Autoantibody (Biphasic hemolysin) that binds to Red Blood Cells after the exposure to the Cold, and then the Red Blood Cells lyse and release Hemoglobin when body is warmed back up to body temperature.

Clinical Presentation:

         Recurrence of a fever and Dark urine 1-2 weeks after a Urinary Tract Infection (UTI)

         Can occur after the exposure to the Cold

         Hemolysis is usually acute and severe

              Hemoglobin < 5 g/dl

 

         Symptoms:

              Fever

              Abdominal Pain

              Hepatosplenomegaly (Enlarged Liver and Spleen)

              Fatigue

              Hemoglobinuria (dark urine; hemoglobin in the urine)

              Pallor

              Jaundice

 

Occurence:

    Occurs more often in children after viral infection but spontaneously resolves.

                Adults are more chronic, but not as severe

 

Diagnosis:

               Identification of symptoms and lab values

               Diagnostic Lab Test: Donath-Landsteiner Test

                            Patient plasma and Cells are incubated at Cold and Warm Temperatures.

                                             If Hemolysis appears in the tubes incubated first at 4C and then at 37C and not in the other tubes, it is Positive.

 

Antibody Specificity:

              The autoantibody is usually IgG with anti-P specificity and is a biphasic hemolysin.

 

Treatment:

             Supportive Therapy through blood transfusion and medications

ANTI-G

The G antigen is present on all RBCs that are D and/or C positive
            rare exception is the  rG cell
                       D and C negative but G positive

Why do we care about the G antigen and its antibody?
           When someone has anti-G it looks like they have antibodies to both D and C antigen
           Generally, you'd transfuse these patients with D negative and C negative blood which so happens to be G negative. So why do we care? If an obstetric patient has anti-G as opposed to anti-D + anti-C they do not have as severe Hemolytic Disease of the Newborn (HDN), but could make anti-D that would cause a severe form of HDN, so RhIg would be indicated.

       How do you know if it is anti-G or anti-D + anti-C?
                  Most reference labs will perform adsorption and elution studies to try to differentiate the two.
                        You'd utilize a D-C+G+ cell and incubate it with the patient's plasma. If anti-G is only present it will be removed from the plasma onto the cell, so when you elute the antibody you will find your eluate will react with both D+C- and D-C+ cells.
                                                 If it is anti-D + anti-C, your eluate will only react with the D-C+ cells.

Red Blood Cell Transfusion

Indications:
        Treatment of anemia in cases too severe to be treated by nutritional replacement or iron
        Loss of 10-15% of total blood volume during surgery
        Correction of perioperative anemia
        Hypotension associated with bleeding

The Transfusion Trigger:
           Generally is having a hemoglobin of 7 g/dl or less.
           If the patient has cardiac problems it is set at 10 g/dl

Why is having a low Hemoglobin and being anemic harmful?
           Hemoglobin transports Oxygen from the lungs to the tissues
           And transports Carbon dioxide from the tissues to the lungs
           Without enough hemoglobin the tissues do not get enough Oxygen and their is a build up of Carbon dioxide. This causes the tissues to become hypoxic and will begin to die. 

How does the body compensate for low hemoglobin levels?
         When hemoglobin levels get below 7 g/dl the heart starts to beat faster to pump blood through the body at a faster rate since their is less blood in the body.
                     This is why those patients with heart problems need to have a transfusion trigger that is higher (like 10 g/dl) because their heart cannot compensate.
          The tissues have a stronger affinity for Oxygen and will grab more of it as the Hemoglobin molecule passes by.

The risk of death from anemia is when the hemoglobin level reaches 3 g/dl. The body cannot compensate for the lack of oxygen and the body begins to shut down. Prolonged levels of a Hemoglobin of 3 or less usually results in death.

Red Blood Cell (RBCs) Transfusions:
        One unit of RBCs can increase the Hemoglobin by 1 g/dl and can be life saving in patients with severe anemia or bleeding.

What is a Type & Screen?

Do you know what testing is done on your blood when a doctor orders a type and screen?
     It is actually two tests:
          The Type:
              Determine your ABO and Rh type
                      Look for the A or B antigen on the Red Blood Cell and for anti-A or anti-B in the plasma
                                     This determines your ABO type
                     Look for the D antigen on the Red Blood Cell
                                     This determines if you are Rh positive or negative

         The Screen:
              Look for antibodies to Red Blood Cell antigens that have developed due to exposure to foreign Red Blood Cells through transfusion, pregnancy, or sharing of blood via needles.
              It is interpreted as either Positive or Negative
                      For Positive Antibody Screens, the antibody is identified and future blood transfusions should not have the Red Blood Cell antigen to the identified antibody.


What is meant by Type & Cross?
        This means that the doctor wants the lab to perform a Type & Screen, plus crossmatch Red Blood Cell untis for transfusion.