MLS 2304 Anemia Workup: Iron, Heme & Chapter 16–17 Patterns

What are the four categories of iron or heme issues?

Missing, trapped, unusable, or excess iron.

What does iron deficiency anemia (IDA) indicate?

A diagnosis of iron deficiency with a need to determine the source of iron loss or mismatch.

What laboratory pattern indicates Stage 1 of iron deficiency?

Ferritin decreases, serum iron is often normal, and Hgb/Hct are normal.

What happens in Stage 2 of iron deficiency?

Iron stores are exhausted, but most circulating RBCs were made when iron supply was still adequate.

What laboratory changes occur in Stage 2 of iron deficiency?

Ferritin decreases, serum iron decreases, TIBC increases, and reticulocyte hemoglobin decreases.

What characterizes Stage 3 of iron deficiency anemia?

Hgb/Hct decreases, MCV decreases, MCHC decreases, RDW increases, and iron studies show low ferritin and low serum iron.

What is the primary mechanism behind microcytosis?

Microcytosis develops when hemoglobin accumulation is delayed.

What does a low reticulocyte response indicate?

It points toward impaired hemoglobin production, not hemolysis.

What does TIBC measure?

Total iron-binding capacity, indicating how much binding capacity is available.

What does transferrin saturation indicate?

The proportion of iron-binding capacity that is occupied.

What is the role of ferritin in iron metabolism?

Ferritin stores iron and indicates how much storage iron is available.

What is the significance of soluble transferrin receptor (sTfR)?

It indicates whether iron-hungry cells are increasing their demand for iron.

What does an increased FEP/ZPP indicate?

Protoporphyrin accumulation due to impaired heme completion.

What are the four major causes of iron deficiency?

Inadequate intake, increased requirement, impaired absorption, and chronic loss.

What does hypochromia refer to?

Less hemoglobinization in red blood cells, resulting in more central pallor.

What is the relationship between iron stores and anemia development?

Iron stores fall first, leading to iron-restricted erythropoiesis before anemia appears.

What does an increased RDW indicate in iron deficiency anemia?

It indicates variation in red blood cell size, often seen in microcytic anemia.

What is the significance of reticulocyte hemoglobin (Ret-He)?

It reflects the most recent availability of iron for new red blood cells.

What does a low transferrin saturation suggest?

It suggests that there is insufficient iron available for erythropoiesis.

What is the consequence of iron accumulation?

Excessive storage and tissue iron can lead to toxicity and organ damage.

What does microcytosis indicate?

It is evidence that adequate hemoglobin production has been disrupted.

What is the primary function of transferrin?

To transport iron in the plasma.

What does an inadequate reticulocyte response indicate in the context of anemia?

It suggests that the bone marrow is not producing enough red blood cells.

What is the role of macrophages in iron metabolism?

They store iron and recycle it from old red blood cells.

What does a normal serum iron level indicate in Stage 1 of iron deficiency?

It indicates that the marrow can still produce normal red blood cells despite falling iron stores.

What are common causes of iron deficiency anemia (IDA)?

Heavy menstrual bleeding, chronic blood loss, pregnancy/lactation, growth spurts in children/adolescents, bariatric or gastric surgery, pica/pagophagia, celiac disease, chronic NSAID/aspirin use, and repeated blood donation.

What symptoms may indicate iron deficiency anemia?

Fatigue, dyspnea, pallor, glossitis, angular cheilosis, and koilonychia.

What is the typical laboratory response timeline for effective iron replacement?

Reticulocyte hemoglobin improves in ~2 days, reticulocyte count rises in 5-10 days, hemoglobin begins to rise in 2-3 weeks, and Hgb approaches baseline in ~2 months.

What does a failure to respond to iron therapy indicate?

Possible non-adherence, ongoing blood loss, impaired absorption, or incorrect initial diagnosis.

How does inflammation affect iron metabolism?

Inflammation increases hepcidin, which reduces ferroportin activity, trapping iron in storage and limiting its availability for erythropoiesis.

What distinguishes iron deficiency anemia from anemia of inflammation regarding serum iron?

Both can present with low serum iron, but IDA has depleted iron stores while anemia of inflammation has iron trapped in storage.

What is the typical CBC pattern in anemia of inflammation?

Mildly decreased hemoglobin (~8-10 g/dL), usually normocytic/normochromic, with inadequate reticulocyte response.

What are the typical findings in iron deficiency anemia vs. anemia of inflammation?

IDA shows low serum iron, low ferritin, high TIBC; AI shows low serum iron, normal/↑ ferritin, low TIBC.

What role does ferritin play in diagnosing iron deficiency?

Ferritin reflects iron storage; levels

What is the significance of soluble transferrin receptor (sTfR) in distinguishing between IDA and AI?

sTfR rises in true iron deficiency and usually remains normal in anemia of inflammation.

What is the porphyria concept in relation to heme synthesis?

Heme synthesis can fail even when iron is available due to enzyme blocks in the porphyrin pathway, leading to accumulation of upstream compounds.

What is the effect of hepcidin on iron absorption?

Hepcidin decreases iron absorption from the intestine and reduces iron release from macrophages and hepatocytes.

What is the dominant mechanism of anemia of inflammation?

Inflammation redirects iron away from erythropoiesis, leading to iron-restricted erythropoiesis.

What are the implications of mixed patterns of anemia?

Inflammation can mask true iron deficiency, making ferritin levels misleading.

What happens to reticulocyte hemoglobin (Ret-He) in IDA and AI?

Ret-He decreases in both conditions but is particularly low in IDA.

What is the role of IL-6 in anemia of inflammation?

IL-6 stimulates hepcidin production, which decreases ferroportin and traps iron.

What is the typical response of reticulocyte count in iron deficiency anemia?

Reticulocyte count rises as iron therapy begins, indicating a response to treatment.

What is the significance of the Thomas plot in diagnosing anemia?

The Thomas plot uses Ret-He and sTfR/log ferritin to differentiate between absolute iron depletion and functional iron restriction.

What are the potential effects of porphyrin accumulation?

Porphyrin accumulation can lead to selected anemias and photosensitivity.

What is the typical MCV and MCHC in anemia of inflammation?

MCV is usually normal and MCHC is also usually normal.

What does an inadequate reticulocyte response indicate?

It suggests that the body is not producing enough new red blood cells in response to anemia.

What is the relationship between chronic infection and anemia of inflammation?

Chronic infections can lead to increased hepcidin levels, further restricting iron availability for erythropoiesis.

What is the importance of investigating GI blood loss in adult men or postmenopausal women with new IDA?

It is crucial to rule out potential sources of chronic blood loss that could be causing the anemia.

What is the sideroblastic concept?

Iron reaches the erythroblast but cannot be used normally, leading to impaired heme synthesis.

What happens during normal heme production in sideroblastic anemia?

Iron enters erythroblast, undergoes mitochondrial heme synthesis, and is incorporated into heme for hemoglobin production.

What is a ring sideroblast?

An erythroblast with iron accumulated in mitochondria, forming a perinuclear ring.

What are typical iron study results in sideroblastic anemia?

Serum iron and ferritin are increased, TIBC is normal or decreased, and transferrin saturation is increased.

What is the main issue in sideroblastic anemia?

Iron is present but not utilized properly.

What is the significance of Prussian blue stain in microscopy?

It shows iron-laden mitochondria around the erythroblast nucleus, indicating ring sideroblasts.

What are hereditary causes of sideroblastic anemia?

X-linked sideroblastic anemia, mitochondrial disorders, and selected erythropoietic porphyrias.

What are acquired causes of sideroblastic anemia?

Myelodysplastic disorders, alcohol, certain drugs, and lead exposure.

How does lead exposure affect heme synthesis?

Lead blocks ALA dehydratase and ferrochelatase, leading to accumulation of ALA and impaired iron incorporation.

What are the consequences of lead exposure in terms of blood findings?

Increased levels of ALA, FEP/ZPP, and possible microcytic/hypochromic anemia.

What is iron overload?

A condition where iron acquisition exceeds loss, leading to toxic accumulation in organs.

What are the major target organs affected by iron overload?

Liver (cirrhosis), pancreas (diabetes), heart (cardiomyopathy), and skin (increased pigmentation).

What is hereditary hemochromatosis?

A genetic condition where normal iron regulation fails, leading to excessive iron absorption.

What is transfusion-related hemosiderosis?

Iron overload resulting from repeated blood transfusions, as the body cannot excrete the excess iron efficiently.

What laboratory findings suggest iron overload?

Increased serum iron, ferritin, and transferrin saturation.

What is the treatment for hereditary hemochromatosis?

Therapeutic phlebotomy to remove blood and iron or iron chelation to bind excess iron for excretion.

What is the pattern of microcytosis in iron deficiency?

Ferritin decreases, serum iron decreases, TIBC increases, and transferrin saturation decreases.

What is the pattern of microcytosis in anemia of inflammation?

Ferritin normal or increased, serum iron decreases, TIBC decreases, and hepcidin increases.

What is the key clue for sideroblastic anemia?

Presence of ring sideroblasts and elevated FEP/ZPP levels.

What does the final algorithm for microcytic anemia suggest?

Identify whether iron is missing, trapped, unusable, or in excess to determine the underlying cause.

What is the mechanism of iron deficiency anemia?

Iron is missing due to inadequate intake, increased need, malabsorption, or blood loss.

What indicates iron excess in the body?

Ferritin and serum iron are both increased, with transferrin saturation also elevated.

What is the significance of increased RDW in iron deficiency?

It indicates a variation in red blood cell size, which is common in iron deficiency anemia.

What is the role of hepcidin in iron metabolism?

Hepcidin regulates iron absorption and distribution; increased levels can trap iron in macrophages.

What does the presence of coarse basophilic stippling indicate?

It is supportive of lead poisoning but not diagnostic.

What is the relationship between chronic erythroid hyperplasia and iron absorption?

It can suppress hepcidin, leading to increased iron absorption despite overload.

What is the first step in evaluating a patient with anemia?

Start with the patient, not the disease name.

What are the five key questions to organize an anemia workup?

1. Is anemia present? 2. Is the marrow responding? 3. What is the MCV? 4. What do RDW and the film add? 5. What question should the next test answer?

What does a low hemoglobin indicate in the context of anemia?

It indicates that anemia is present but does not identify the cause.

What is the physiological consequence of anemia?

Reduced oxygen delivery to tissues.

How does the rate of hemoglobin decline affect clinical presentation?

A rapid decline can lead to more prominent symptoms, while a slow decline allows for adaptation.

What are the two types of anemia based on the rate of development?

Acute anemia (minutes to hours) and slowly developing anemia (days to weeks).

What compensatory mechanisms occur in acute anemia?

Peripheral vasoconstriction, increased heart rate, respiratory rate, and cardiac output.

What can happen to hemoglobin and hematocrit levels immediately after acute hemorrhage?

They may appear unchanged due to simultaneous loss of RBCs and plasma.

What are the three primary directions in which anemia can begin?

1. Decreased production of RBCs 2. Increased destruction of RBCs 3. Increased blood loss.

What does ineffective erythropoiesis mean?

Precursors are produced, but many fail before release into circulation.

What does a reticulocyte response indicate?

Whether the marrow is keeping up with the demand for RBC production.

What does a high reticulocyte percentage indicate?

It may look increased but can still be inadequate if the absolute count is low.

What is the significance of the absolute reticulocyte count?

It tells you how many reticulocytes are actually circulating in the blood.

What does a corrected reticulocyte count help determine?

How much the reticulocyte percentage is inflated by anemia.

What is the Reticulocyte Production Index (RPI)?

A measure that indicates whether the marrow response to anemia is adequate based on reticulocyte count.

What does an RPI value less than 2 indicate?

An inadequate marrow response.

What is the role of the kidney in anemia?

The kidney increases erythropoietin (EPO) production in response to decreased oxygen delivery.

What can change the differential diagnosis in anemia evaluation?

History and physical findings, such as bleeding history and nutritional risk.

What does the MCV (Mean Corpuscular Volume) indicate in anemia?

It helps classify the type of anemia based on the size of RBCs.

What does RDW (Red Cell Distribution Width) add to the evaluation?

It provides information on the variation in RBC size, which can indicate different types of anemia.

What is the importance of patient factors in anemia diagnosis?

Patient factors can influence symptoms and the interpretation of laboratory results.

How does chronic blood loss affect anemia production mechanisms?

Chronic blood loss can eventually create iron-restricted production.

What is the difference between effective, ineffective, and insufficient erythropoiesis?

Effective produces functional RBCs, ineffective produces precursors that fail, and insufficient produces too few precursors.

What does a reticulocyte percentage of 3.0% indicate?

It looks increased, but the response may still be inadequate for the degree of anemia.

What does the term 'compensation' refer to in anemia?

The body's mechanisms to preserve oxygen delivery despite anemia.

What happens to erythropoiesis after acute blood loss?

Marrow increases erythropoiesis, leading to reticulocytosis.