Megaloblastic Anemia: Causes, Diagnosis, and Treatment

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Questions and Answers

What is the most common cause of vitamin B12 deficiency?

Poor absorption (correct)

Dietary deficiency

Autoimmune chronic gastritis

Gastric biopsy

What is the primary mechanism of folic acid absorption?

Deconjugation and conversion to the monoglutamate form in the stomach

Simple diffusion in the ileum

Passive diffusion in the jejunum (correct)

Active transport in the duodenum

What is the typical presentation of megaloblastic anemia?

Hemolytic anemia with fever

Normocytic anemia with joint pain

Macrocytic anemia with neurological symptoms (correct)

Microcytic anemia with gastrointestinal symptoms

What is the treatment for pernicious anemia?

Lifelong vitamin B12 replacement therapy Signup and view all the answers

What is the primary cause of pernicious anemia?

Autoimmune chronic gastritis Signup and view all the answers

What is the daily requirement of folic acid?

100 µg/day Signup and view all the answers

What is the most common cause of Folate deficiency?

Inadequate dietary intake of Folate Signup and view all the answers

Which of the following is a clinical feature of megaloblastic anemia due to Folate deficiency?

Glossitis with a smooth red beefy tongue Signup and view all the answers

Which of the following increases the requirement for Folate?

All of the above Signup and view all the answers

What is the earliest symptom of neurological dysfunction due to Vitamin B12 deficiency?

Parasthesia in the distal limbs Signup and view all the answers

Which of the following drugs can impair the utilization of Folate?

All of the above Signup and view all the answers

What is the pathology of neurological dysfunction due to Vitamin B12 deficiency?

All of the above Signup and view all the answers

What is the primary cause of megaloblastic anemia?

Vitamin B12 deficiency Signup and view all the answers

What is the characteristic feature of erythroblasts in megaloblastic anemia?

They have immature nuclei Signup and view all the answers

What is the effect of vitamin B12 deficiency on DNA synthesis?

It inhibits DNA synthesis Signup and view all the answers

What is the treatment for megaloblastic anemia?

Vitamin B12 supplementation Signup and view all the answers

What is the effect of folic acid deficiency on erythropoiesis?

It inhibits erythropoiesis Signup and view all the answers

What is the hallmark of non-megaloblastic macrocytosis?

Abnormal RBC membrane structure Signup and view all the answers

Study Notes

Macrocytosis and Megaloblastic Anemia

Macrocytosis is a condition where red blood cells (RBCs) are larger than normal, with a mean corpuscular volume (MCV) > 100 fl.

Non-Megaloblastic Macrocytosis

Causes include:
- RBC membrane abnormalities (e.g., liver disease, myxedema, alcoholism)
- Aplastic anemia
- Myelodysplastic syndrome (MDS)
- Acquired sideroblastic anemia
- Reticulocytosis
- Pregnancy and newborns

Megaloblastic Anemia

Characterized by high MCV (>120 fl) and defective DNA synthesis
Erythroblasts are larger than normal with immature nuclei (nuclear-cytoplasmic asynchrony)
Causes include:
- Deficiency of vitamin B12 and/or folic acid (most common)
- Drugs that interfere with DNA nucleotide base synthesis (e.g., purine analogues, pyrimidine analogues)
- Intrinsic factor deficiency
- Certain diseases (e.g., Crohn's disease, pancreatic insufficiency)

Vitamin B12 Deficiency

Causes include:
- Dietary deficiency (rare, e.g., vegans)
- Poor absorption (most common cause)
- Malabsorption (e.g., pernicious anemia, gastrectomy, old age)
- Certain infections (e.g., Diphyllobothrium latum, Helicobacter pylori)
- Certain drugs (e.g., proton pump inhibitors)

Pernicious Anemia

A type of megaloblastic anemia caused by autoimmune chronic gastritis
Common in Caucasians, both genders, and those with a family history
Typically presents at age 60 years
Associated with other autoimmune disorders (e.g., blue eyes, premature graying, vitiligo)

Folic Acid (Folate)

A water-soluble vitamin essential for DNA synthesis
Abundant in vegetables, fruits, dairy products, and liver
Natural folates are in polyglutamate form, which is converted to monoglutamate for absorption
Absorption occurs in the jejunum
Requirement: 100 µg/day
Body stores: 10 mg in the liver (can last 4 months or less in alcoholics)

Folate Deficiency

Causes include:
- Dietary deficiency (most common)
- Impaired absorption (e.g., celiac disease, resection)
- Impaired utilization (e.g., certain drugs, alcohol)
- High requirement (e.g., pregnancy, dialysis, hemolysis)
- High loss (e.g., heart failure, chronic liver disease)

Clinical Features of Megaloblastic Anemia

Chronic and asymptomatic, with insidious onset
Non-specific symptoms: burning tongue, weight loss, diarrhea, sterility, impotence
Depression, Alzheimer disease, atherosclerosis, and thrombosis
Signs: pallor, mild jaundice, glossitis, smooth red beefy tongue, aphthous ulcers, hyperpigmentation, and splenomegaly

Neurological Dysfunction in Vitamin B12 Deficiency

Pathology: subacute combined degeneration of the spinal cord
Demylination and axonal degeneration can occur at any time
Severity is inversely related to anemia
Sensory and motor deficits, with parasthesia in distal limbs as the earliest symptom

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Description

Explore the world of anemia! This quiz covers the causes of macrocytosis, B12 and folate metabolism, diagnosis, and treatment of megaloblastic anemia. Test your knowledge and revise your understanding of this important topic in hematology.