Hematology: Hypochromic Microcytic Anemias, Thalassemia, and Sideroblastic Anemia

A comprehensive set of 50 practice flashcards reviewing hematology lecture concepts, including iron deficiency anemia, thalassemia minor and major, sideroblastic anemia, analyzer histograms, and red cell indices.

In the initial patient report reviewed, what hemoglobin value primarily triggered the slide review?

A hemoglobin value of $60$.

What red cell count value was observed in the initial case that aligned with iron deficiency?

A low red count of $3.3$.

Which MCV threshold defines a microcytic red blood cell population according to the lecture?

An MCV below $80$.

Which MCH and MCHC values indicated hypochromasia in the introductory patient case?

An MCH of less than $30$ and an MCHC of less than $320$.

What specific morphologies does the technologist examine on the smear to confirm the analyzer's findings?

Polychromasia, nucleated red cells, and inclusions.

Under what condition is polychromasia formally reported on a blood film?

Only when it is increased.

What RDW value prompted the analyzer to flag for anisocytosis in the first case?

An RDW of $23$ ($24$ rounded).

How does an automated analyzer mathematically differentiate between iron deficiency and thalassemia?

It uses a mathematical calculation index formula where specific cutoff values favor either iron deficiency or thalassemia.

In Case 77, what platelet finding walked with a diagnosis of iron deficiency?

A slightly increased platelet count.

How was the histogram characterized in Case 77 with an RDW of $25$?

It was quite wide and represented a blended population without two humps (not a dual population).

Why is the rule of three rarely used in modern clinical hematology laboratories?

Almost $100\%$ of modern laboratories use auto release criteria for normal CBC results, so normal samples are not made into slides.

What percentage of slides processed through automated analyzers typically require manual slide review?

About $20\%$ of slides.

Under what specific condition does the rule of three apply?

Only if the red cell indices are normal.

On a Sysmex analyzer histogram, what does the dark shadow feature represent?

The expected range where a normal red blood cell population should fall.

What was the purpose of the 'I\'m channel' on older Sysmex XT series analyzers?

It identified abnormal white cell populations.

What technology replaced the 'I\'m channel' in modern Sysmex analyzers to generate the IG flag?

Fluorescence technology.

How does an Advia analyzer primarily generate its red cell histogram?

By sphering the red cells and analyzing the red cells directly.

On an Advia cytogram, which quadrants correspond to microcytosis and hypochromasia?

Microcytosis is represented along the bottom end and hypochromasia is toward the side quadrant.

In the Advia analyzer example, why was leukemia ruled out when evaluating hemoglobin?

The standard hemoglobin of $78$ correlated closely with the optical hemoglobin of $76$.

Why should laboratory technologists interpret automated analyzer grading of indices with caution?

The analyzer\'s preprogrammed grading criteria may not align with the grading criteria established by the specific laboratory.

What unexpected red cell count was noted in the case presenting with thalassemia minor?

A red cell count of $5.94$, which is on the high end of normal or outside the normal reference range.

What hemoglobin thresholds were specified for defining anemia in women and men?

Less than $120$ for females and less than $140$ for males.

What was the RDW value in the thalassemia minor case, and what is its normal cutoff?

The RDW was $14.5$, which is normal because an RDW under $16$ is considered normal.

What automated query did the analyzer generate instead of iron deficiency in the thalassemia minor patient?

Query hemoglobin defect.

Why does the body produce an increased red cell count in thalassemia minor?

To compensate for hypoxia caused by defective hemoglobin by producing a much higher volume of red cells.

Why does iron deficiency present with a low red cell count compared to thalassemia?

Iron deficiency lacks the necessary iron ingredients to make red cells, whereas thalassemia has the ingredients but cannot assemble normal globin chains.

What is the primary pathophysiology of sideroblastic anemia?

Ineffective utilization of iron due to a defect in mitochondrial heme synthesis, resulting in iron being trapped inside red cells or red cell precursors.

What is considered the most common, albeit extremely rare, form of sideroblastic anemia?

The inherited form.

What acquired conditions can cause sideroblastic anemia?

Long-term chronic alcohol abuse and myelodysplasia.

Which red cell inclusions are visible on the peripheral blood smear in sideroblastic anemia?

Pappenheimer bodies (small iron particles).

What diagnostic procedure and stain provide the definitive diagnosis for sideroblastic anemia?

A bone marrow smear stained with Prussian blue stain.

What pathognomonic feature appears on a Prussian blue-stained bone marrow smear in sideroblastic anemia?

Ringed sideroblasts, which are rings of trapped iron deposits encircling the nucleus of red cell precursors.

Into which morphological category do sickle cell anemia and thalassemias fall, respectively?

Sickle cell anemia is normochromic normocytic, whereas thalassemias are hypochromic microcytic.

How does the molecular defect in thalassemia differ from that of sickle cell anemia?

Thalassemia involves a quantitative defect affecting the entire globin chain synthesis, whereas sickle cell anemia involves a single amino acid substitution.

Approximately how many distinct hemoglobinopathies exist?

Over $1000$ different hemoglobinopathies.

Why are most of the over $1000$ hemoglobinopathies not clinically monitored?

Most are clinically silent or asymptomatic, allowing the body to transport oxygen adequately without medical concern.

How many amino acids compose the alpha globin chain?

$141$ amino acids.

How many amino acids compose the beta globin chain?

$146$ amino acids.

What are three physical or physiological manifestations produced by clinically significant hemoglobinopathies?

Physical sickling of cells, precipitation of unstable hemoglobin (forming Heinz bodies), and altered oxygen affinity causing chronic hypoxia.

What percentage of normal adult hemoglobin is composed of hemoglobin A and fetal hemoglobin, respectively?

Hemoglobin A comprises about $95\%$ and fetal hemoglobin (HbF) typically comprises $2\%$.

By what age should an infant fully transition from fetal hemoglobin to an adult hemoglobin distribution?

By the age of $2$.

Why are infants with beta thalassemia major typically asymptomatic at birth?

Newborns primarily produce fetal hemoglobin (HbF) composed of gamma chains, which does not require normal beta globin chains.

How many genes code for alpha globin versus beta globin on each chromosome?

Two genes code for alpha globin per chromosome, whereas only one gene codes for beta globin per chromosome.

What genetic state characterizes thalassemia minor (carrier or trait)?

Inheriting an abnormal globin gene from only one parent.

What historical eponym was used for beta thalassemia major?

Coulee\'s anemia.

Which specific demographic in Northern Ontario, notably in Sault Ste. Marie, has a high prevalence of beta thalassemia?

The Italian population.

During what clinical events can asymptomatic thalassemia minor patients experience complications?

Periods of high physiological stress, such as surgeries or pregnancy.

How do codocyte and basophilic stippling findings contrast between thalassemia minor and thalassemia major?

They are rarely observed in thalassemia minor, but are expected or almost always present in thalassemia major.

Which two clinical chemistry analytes become elevated due to increased premature red cell destruction in thalassemia?

Bilirubin and lactate dehydrogenase (LD).

Why should physicians avoid prescribing iron therapy to patients with thalassemia?

Thalassemia is not caused by iron deficiency and the patients have normal iron levels; therefore, iron therapy provides no clinical benefit and will not correct the anemia.