MLT Registration flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

ABO forward vs reverse typing

Forward typing detects antigens on red cells with anti-A and anti-B; reverse typing detects serum antibodies with A1 and B cells. Discrepancies require resolution before transfusion.

Weak D testing

Weak D test is performed on all initially D-negative patients. D-negative females of childbearing age receive RhIG at 28 weeks and within 72 hours of delivery.

Acute hemolytic transfusion reaction

Most commonly caused by clerical error leading to ABO incompatibility. Signs include fever, chills, flank pain, hemoglobinuria, and DIC. Stop transfusion immediately and report.

Febrile nonhemolytic reaction

Most common transfusion reaction, caused by cytokines or leukocyte antibodies. Treated with antipyretics; future transfusions use leukoreduced products.

Beer-Lambert law

Absorbance equals molar absorptivity times path length times concentration (A = εbc). Absorbance is directly proportional to concentration and path length.

Hexokinase glucose method

Reference method for glucose: hexokinase converts glucose to glucose-6-phosphate, then dehydrogenase produces NADH measured at 340 nm. Fluoride oxalate inhibits glycolysis.

Jaffe creatinine reaction

Alkaline picrate reacts with creatinine to form a colored complex. Kinetic alkaline picrate reduces interference; enzymatic method is more specific.

Anion gap

Calculated as sodium minus (chloride plus bicarbonate); normal 8-12 mEq/L. Elevated in ketoacidosis, lactic acidosis, renal failure, and toxin ingestion.

Westgard rules

Quality control acceptance rules: 1-2s warning, 1-3s rejection, 2-2s rejection, R-4s rejection, 4-1s rejection, 10x rejection. Used with Levey-Jennings charts.

PT and INR

PT measures extrinsic and common pathway factors. INR = (patient PT / normal PT)^ISI; used to monitor warfarin therapy, therapeutic range typically 2.0-3.0.

APTT

Measures intrinsic and common pathway factors (XII, XI, IX, VIII, X, V, II, fibrinogen). Used to monitor unfractionated heparin; therapeutic range 1.5-2.5 times normal.

Mixing study

Prolonged PT or APTT is mixed with normal plasma. Correction indicates factor deficiency; failure to correct indicates an inhibitor such as lupus anticoagulant or factor VIII inhibitor.

DIC laboratory findings

Disseminated intravascular coagulation shows prolonged PT and APTT, low platelets, low fibrinogen, elevated D-dimer, and schistocytes on smear. Treat underlying cause.

MCV

Mean corpuscular volume = (hematocrit × 10) / RBC count in millions. Microcytic <80 fL, normocytic 80-100 fL, macrocytic >100 fL.

Iron deficiency anemia

Microcytic anemia with low ferritin, low serum iron, high TIBC, and low saturation. Ferritin is the most sensitive indicator of iron stores.

Anemia of chronic disease

Normocytic or microcytic anemia with low serum iron, low TIBC, and normal or high ferritin. Caused by inflammation and hepcidin-mediated iron sequestration.

Reticulocyte production index

Corrected reticulocyte count = reticulocyte % × (patient Hct / normal Hct). RPI adjusts for maturation and indicates marrow response; >2 suggests adequate response.

Hemolysis markers

Elevated reticulocyte count, indirect bilirubin, and LDH with decreased haptoglobin suggest hemolysis. Direct antiglobulin test distinguishes immune from non-immune causes.

Immunoglobulin classes

IgG monomer crosses placenta; IgM pentamer is first responder and fixes complement; IgA dimer with J chain protects mucosa; IgE mediates type I hypersensitivity.

Hypersensitivity types

Type I IgE mast cell (anaphylaxis); type II antibody-mediated (hemolytic transfusion reaction); type III immune complex (SLE); type IV delayed T-cell (tuberculin).

ANA and anti-dsDNA

ANA is sensitive for SLE; anti-dsDNA and anti-Sm are specific. Anti-dsDNA levels correlate with disease activity and lupus nephritis.

Transplant rejection types

Hyperacute from preformed antibodies; acute cellular rejection days to weeks; chronic rejection with fibrosis months to years. HLA typing and crossmatch prevent hyperacute rejection.

Gram stain

Gram-positive organisms stain purple; gram-negative pink. Cocci in clusters suggest Staphylococcus; chains Streptococcus; pairs Neisseria; rods Enterobacteriaceae or Pseudomonas.

Catalase and coagulase

Staphylococcus aureus is catalase-positive and coagulase-positive. Coagulase-negative staphylococci are less pathogenic and often skin flora.

Streptococcus pneumoniae

Alpha-hemolytic, optochin-sensitive diplococcus. Most common cause of community-acquired pneumonia; vaccine available for high-risk groups.

Urine culture colony count

Colony count ≥10^5 CFU/mL in midstream urine suggests urinary tract infection. Mixed flora suggests contamination; E. coli is most common pathogen.

Acid-fast stain

Ziehl-Neelsen stain detects mycobacteria; acid-fast bacilli appear red. Culture on Lowenstein-Jensen or liquid media; slow growth 2-6 weeks.

Order of draw

Blood cultures, light blue citrate, serum red/gold, heparin green, EDTA lavender, fluoride oxalate gray. Follow to avoid cross-contamination of additives.

Tourniquet time

Apply tourniquet 3-4 inches above site and release within 1 minute. Prolonged tourniquet causes hemoconcentration and falsely elevates potassium and protein.

Hemolysis effects

Hemolysis falsely elevates potassium, LDH, and AST. Avoid excessive suction, small needles, shaking tubes, and squeezing capillary sites.

CLIA complexity

CLIA categorizes tests as waived, moderate, or high complexity. Waived tests are simple with low risk; moderate and high require documented training and competency.

Proficiency testing

Unknown samples from an approved provider; results must be within acceptable limits. Failure triggers corrective action and possible sanctions under CLIA.