Phlebotomy Vacutainer Techniques Quiz

Hemosiderin consists of insoluble iron complexes formed after red blood cell breakdown. Iron binds to proteins, lipids, and carbohydrates, making it water-insoluble. It accumulates in macrophages during iron overload or hemorrhage, distinguishing it from ferritin which is soluble.

Perl’s Prussian Blue reaction requires potassium ferrocyanide and hydrochloric acid. Acid releases ferric iron, which reacts with ferrocyanide to form blue ferric ferrocyanide. Precise concentrations are essential for accurate iron visualization.

The iron counterstain balances nuclear detail and background contrast. Nuclear fast red stains nuclei, while basic fuchsin enhances cytoplasmic detail. Incorrect ratios can obscure iron granules or overstain tissue.

Hgb H stain identifies hemoglobin H inclusions formed in alpha thalassemia. These inclusions appear as precipitates in red cells, confirming defective alpha chain production.

Hemoglobin H is composed of four beta chains. This abnormal tetramer forms when alpha chains are deficient, leading to unstable hemoglobin and hemolysis.

Alkali denaturation exploits the resistance of fetal hemoglobin to alkaline conditions. Hgb F remains stable while adult hemoglobin denatures, allowing quantification useful in thalassemia diagnosis.

Phosphate buffer promotes hemoglobin polymerization under deoxygenated conditions. Saponin lyses red cells, releasing hemoglobin for observation of turbidity in sickle cell screening.

Unstable hemoglobins denature at elevated temperatures. Incubation at 50°C causes precipitation, identifying variants that destabilize under heat stress.

G6PD and NADP are required to generate NADPH. Lack of fluorescence under UV light indicates enzyme deficiency due to impaired NADPH production.

Drabkin’s reagent converts hemoglobin to methemoglobin using ferricyanide. Cyanide then forms cyanmethemoglobin, producing a stable color for spectrophotometric measurement.

ESR increases with elevated plasma proteins seen in bacterial infections and multiple myeloma. These proteins promote rouleaux formation, increasing sedimentation rate.

A refractive index of 1.52 matches glass and immersion oil, minimizing light refraction and improving microscopic resolution.

A left shift on RBC histogram indicates smaller cells. Microcytosis is commonly associated with iron deficiency and thalassemia.

Heinz bodies reflect oxidative damage to hemoglobin. They appear in G6PD deficiency, unstable hemoglobin disorders, and after toxin exposure.

Heinz bodies are precipitated denatured hemoglobin attached to red cell membranes. They signify oxidative stress and membrane damage.

LAP stain differentiates chronic myeloid leukemia from reactive conditions. CML shows low LAP, while leukemoid reactions show high activity.

Heparin preserves enzyme activity needed for LAP staining. EDTA and citrate interfere with enzymatic reactions.

LAP scoring evaluates neutrophils and band cells only. Other leukocytes do not express significant alkaline phosphatase activity.

Elevated LAP occurs in reactive conditions like leukocytosis and polycythemia vera due to increased neutrophil enzyme activity.

Low LAP scores are characteristic of myeloproliferative disorders such as CML and AML where enzyme activity is reduced.

CLL typically presents with normal LAP because neutrophil function remains unaffected, unlike other proliferative disorders.

Peroxidase stain detects myeloid lineage by identifying peroxidase enzyme in blasts. Positivity above 3% supports AML diagnosis.

Benzidine hydrochloride reacts with peroxidase to form colored products, indicating enzyme presence within leukocytes.

Blue-black cytoplasmic granules in granulocytes and monocytes indicate peroxidase activity, confirming myeloid origin.

Excess serum proteins, lipids, or transfused blood can interfere with turbidity, producing false positive sickle screens.

Washing cells removes interfering proteins, improving specificity of sickle cell screening and reducing false positives.

Severe anemia lowers hemoglobin concentration, masking sickling reactions and causing false negative results.

Isopropanol precipitation detects unstable hemoglobins that may migrate normally on electrophoresis but precipitate under stress.

Non-polar isopropanol destabilizes hemoglobin. Unstable variants precipitate rapidly, confirming abnormal hemoglobin structure.