ASCP SH flashcards

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

Erythropoietin production site

Peritubular interstitial cells of the renal cortex synthesize erythropoietin when tissue oxygen tension falls; the hormone then stimulates CFU-E proliferation and differentiation into hemoglobin-synthesizing erythroblasts.

Adult hemoglobin composition

HbA (alpha2 beta2) makes up about 95-97% of adult red cell hemoglobin, HbA2 (alpha2 delta2) is below 3.5%, and HbF (alpha2 gamma2) is below 2%.

Reticulocyte production index formula

Corrected reticulocyte percentage equals the raw reticulocyte percentage multiplied by the patient hematocrit divided by 45; the RPI divides that corrected value by the maturation factor, with an RPI above 3 indicating an adequate marrow response.

Right shift oxygen dissociation curve

Elevated 2,3-BPG, hydrogen ion, carbon dioxide, and temperature lower hemoglobin oxygen affinity, shifting the curve rightward and increasing oxygen unloading to tissues; the normal P50 is about 26-27 mmHg.

Hereditary spherocytosis membrane defect

Defects in vertical membrane linkages involving spectrin, ankyrin, band 3, or protein 4.2 cause loss of membrane surface area, producing spherocytes with increased osmotic fragility and elevated MCHC.

Erythrocyte lifespan and removal

Normal red cells circulate roughly 120 days before senescent membrane changes lead to removal by splenic macrophages; the axial skeleton marrow is the main adult production site.

Hematopoietic stem cell markers

Primitive hematopoietic stem cells are CD34 positive, CD38 negative, and lineage negative; CD117 (c-kit) marks committed progenitors, and erythropoietin drives CFU-E maturation.

Iron deficiency laboratory pattern

Low serum ferritin, low serum iron, elevated total iron binding capacity, transferrin saturation below 15%, elevated soluble transferrin receptor and zinc protoporphyrin, and frequently reactive thrombocytosis.

Anemia of chronic disease pattern

Hepcidin-mediated iron sequestration produces low serum iron and low TIBC with normal or elevated ferritin and saturation near 15-20%; the anemia is typically normocytic and normochromic.

Beta thalassemia trait findings

Microcytosis with an increased red cell count and elevated HbA2 between 3.5 and 8%; HbF may be mildly raised and iron studies are normal, distinguishing it from iron deficiency.

Sickle cell screening tests

Hemoglobin S arises from beta-globin glutamic acid to valine substitution at position 6; it sickles when deoxygenated and migrates more slowly than HbA on alkaline electrophoresis, with confirmation by HPLC or DNA testing.

B12 versus folate deficiency

Vitamin B12 deficiency raises both methylmalonic acid and homocysteine, whereas folate deficiency raises homocysteine only; both cause macrocytic anemia with hypersegmented neutrophils.

G6PD deficiency blood findings

This X-linked enzyme defect causes episodic oxidative hemolysis with Heinz bodies, bite cells, and hemoglobinuria; enzyme assay performed during acute hemolysis may be falsely normal because older deficient cells have lysed.

Warm autoimmune hemolysis features

IgG-coated red cells are cleared by splenic macrophages, producing spherocytes, a positive anti-IgG direct antiglobulin test, reticulocytosis, elevated indirect bilirubin, and low haptoglobin.

Leukemoid reaction versus CML

A leukemoid reaction shows high leukocyte alkaline phosphatase, toxic granulation, Dohle bodies, and no basophilia, while CML shows basophilia, low alkaline phosphatase, and BCR-ABL1.

Auer rod significance

Needle-shaped azurophilic inclusions formed from fused primary granules in myeloblasts indicate acute myeloid leukemia, most often FAB subtypes M2, M3, or M4.

Acute promyelocytic leukemia hallmark

t(15;17) creating PML-RARA, hypergranular promyelocytes, Auer rods, and disseminated intravascular coagulation at presentation; all-trans retinoic acid induces terminal differentiation of the malignant clone.

CLL immunophenotype

Chronic lymphocytic leukemia B cells are CD5 positive, CD19 positive, CD23 positive, FMC7 negative, and show dim surface immunoglobulin; smudge cells are a typical film finding.

Reed-Sternberg cell markers

Classic Hodgkin lymphoma Reed-Sternberg cells are CD15 positive, CD30 positive, CD45 negative, and usually CD20 negative, which separates them from non-Hodgkin lymphoma cells.

Hairy cell leukemia markers

Mature B cells coexpressing CD11c, CD25, CD103, and tartrate-resistant acid phosphatase cause pancytopenia with monocytopenia, splenomegaly, a dry marrow aspirate, and fried-egg marrow cells.

PT versus APTT coverage

Prothrombin time evaluates factors VII, X, V, II, and fibrinogen, covering the extrinsic and common pathways; activated partial thromboplastin time evaluates XII, XI, IX, VIII, X, V, II, and fibrinogen.

Mixing study interpretation

Correction of a prolonged clotting time after adding normal pooled plasma indicates factor deficiency; failure to correct immediately or after incubation at 37 C suggests an inhibitor or heparin contamination.

von Willebrand disease pattern

Reduced von Willebrand factor antigen and ristocetin cofactor activity with low factor VIII; ristocetin-induced platelet aggregation is abnormally low and corrects when normal plasma is added.

Vitamin K dependent factors

Factors II, VII, IX, X and proteins C and S require vitamin K-dependent gamma carboxylation; factor VII has the shortest half-life, so the prothrombin time prolongs before the APTT.

DIC laboratory constellation

Disseminated intravascular coagulation shows thrombocytopenia, prolonged PT and APTT, low fibrinogen, elevated D-dimer and fibrin degradation products, and schistocytes on the peripheral film.

Heparin and warfarin monitoring

Unfractionated heparin prolongs the APTT and is reversed by protamine; warfarin reduces vitamin K-dependent factors and is monitored by prothrombin time and INR, reversed with vitamin K.

EDTA and citrate uses

EDTA chelates calcium and preserves blood cell morphology for the CBC; 3.2% sodium citrate at nine parts blood to one part anticoagulant is the standard specimen for coagulation testing.

Cold agglutinin specimen correction

Cold agglutinins cause falsely low red cell and platelet counts with falsely high MCV and MCHC; warming the EDTA tube to 37 C and rerunning the sample corrects these interferences.

Westgard 1-3s rule

A single control result exceeding the mean by three standard deviations rejects the analytical run; this rule is a random error indicator displayed on a Levey-Jennings chart.

Westgard 2-2s rule

Two consecutive control values exceeding two standard deviations, either on the same material or across two materials, indicate systematic error and require rejection of the run.

Reticulocyte supravital stain

New methylene blue or brilliant cresyl blue precipitates reticulocyte ribosomal RNA into visible filaments; fluorescent nucleic acid dyes allow flow cytometric enumeration of the same cells.

ESR limitations

The Westergren sedimentation rate rises with anemia, pregnancy, and inflammation and falls with polycythemia, spherocytosis, and sickle cells; it is a nonspecific acute-phase indicator only.