labCE Flashcards
which of the following is an autoantibody that binds to TSH receptor sites on thyroid cell membranes preventing thyroid-stimulating hormone binding?
thyroid-stimulating immunoglobulins
*Thyroid-stimulating immunoglobulins, or TSI’s, are IgG antibodies that can bind to thyrotropin (TSH) receptors on the thyroid gland. TSIs mimic the action of TSH, causing excess secretion of thyroxine and triiodothyronine. The TSI level is abnormally high in persons with hyperthyroidism due to Graves’ disease.
the use of the direct antiglobulin test is indicated for what ?
transfusion reactions
autoimmune hemolytic anemia
HDN
*The direct antiglobulin test (DAT) detects antibodies coating RBCs. Alloantibodies are primarily detected in the serum, although they may also sometimes be eluted from previously transfused RBCs in the patient’s blood.
what is the most prudent step to follow to select units for cross-match after recipient antibodies have been IDENTIFIED?
antigen type patient cells and any donor cells to be cross-matched
*After any significant antibodies have been identified, the technologist must antigen type any blood cell units for the recipient along with a cross-match to prevent transfusion reactions.
what is the MOST common cause of acute hemolytic transfusion reactions?
clerical errors
*Acute hemolytic transfusion reactions are rare, but when they do occur, they are usually life-threatening. Clerical errors that include mislabeling blood or misidentification of patients, account for 80% of these reactions.
a patient experiences a mild allergic rxc to a transfusion; including, urticaria, erythema (skin redness), and itching. what is the most likely source of the allergen?
plasma proteins
*Mild allergic reactions result from a patient’s hypersensitivity to soluble allergens in the plasma of the donor unit. The blood recipient forms antibodies to these allergens that are bound to IgE on mast cells and cause the release of histamines. Allergen substances may be drugs or food consumed by the blood donor.
which procedure should be followed when one cross-matched unit out of five is INCOMPATIBLE at the antiglobulin (AHG) phase ?
perform a direct antiglobulin test (DAT) on the incompatible unit
*If the patient’s serum is incompatible with only one unit at the AHG phase, the donor unit may have a positive DAT. If the test is positive, the donor unit should not be used for transfusion.
