Microcytic Anaemia Flashcards by Caitlin McMullen

Define Microcytic Anaemia

Anaemia caused by deficient haemoglobin synthesis
→ cytoplasmic defect leading to reduced Hb production

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Where is Hb synthesised?

Cytoplasm

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What is the acronym for common causes of microcytic anaemia?

TAILS
T- Thalassaemia
A- Anaemia of chronic disease
I- Iron deficiency
L- Lead poisoning
S- Sideroblastic anaemia

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What is the most common cause of microcytic anaemia?

Iron deficiency

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What is the mechanism of anaemia of chronic disease?

Inflammatory cytokine (IL-6) increases ferritin and hepcidin, blocking iron release and impairing erythropoiesis.

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What is sideroblastic anaemia?

A disorder were there is defective haem synthesis, causing iron to accumulate in mitochondria instead of being incorporated into haem. Is x linked

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Examples that cause Sideroblastic anaemia

MDS, lead poisoning, alcohol excess

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What are causes of iron deficiency?

(1) Insufficient intake

(2) Chronic blood loss (eg, menorrhagia, GI bleeding)

(3) Malabsorption (e.g., coeliac disease)

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What is the pathophysiology of microcytic anaemia?

Lack of Hb in the cytoplasm delays the normal stop signal for red cell division, leading to smaller (microcytic) and hypochromic cells

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How is iron transported and stored in the body?

Iron is transported by transferrin and stored in ferritin

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What is the iron metabolic pathway in the body?

Iron is absorbed, transported by transferrin, and stored in ferritin. The system is closed, with limited iron absorption

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How does iron deficiency lead to microcytic anaemia?

Depleted iron stores reduce erythropoiesis, leading to smaller, hypochromic red blood cells

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What are the clinical features of iron deficiency anaemia?

(1) Fatigue
(2) Pallor
(3) Brittle nails
(4) Angular stomatitis
(5) Glossitis
(6) and in chronic cases, epithelial changes

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What investigations are used in the diagnosis of microcytic anaemia?

Blood count and film, serum ferritin, and transferrin saturation

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What is the management of iron deficiency anaemia?

Iron supplements (oral or IV), dietary changes, and addressing underlying causes like GI bleeding

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What test helps distinguish between poor compliance and blood loss in anaemia?

Reticulocyte count

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How does anaemia of chronic disease affect iron metabolism?

Increased ferritin and hepcidin reduce iron absorption, leading to hypochromic red cells

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What is the role of transferrin and ferritin in iron metabolism?

Transferrin transports iron, while ferritin stores it in cells. Serum ferritin levels reflect iron stores

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How does anaemia of chronic disease affect iron and transferrin levels?

It leads to low serum iron, high ferritin, and low transferrin saturation

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How are red blood cells affected in iron deficiency anaemia?

Red cells are microcytic (MCV <80 fL) and hypochromic (low MCH), with poikilocytosis and anisocytosis

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How does sideroblastic anaemia differ from iron deficiency anaemia?

Sideroblastic anaemia presents with microcytic anaemia that does not respond to iron replacement therapy

How should response to iron therapy be monitored?

Assess Hb levels after 4–6 weeks; typically continue treatment for 2–3 months to replenish iron stores

What does high reticulocytes indicates?

Blood loss

What happens first in negative iron balance?

Exhaustion of iron stores, causing ferritin levels to fall

What occurs after iron stores are exhausted?

Iron-deficient erythropoiesis starts, and MCV begins to fall

What develops as a result of a negative iron balance?

Microcytic anaemia

What are some epithelial changes in iron deficiency?

Koilonychia (spoon-shaped nails) and angular cheilitis (skin condition that causes inflammation at the corners of the mouth)

What is the difference between the types of microcytic anaemia?

Microcytic anaemia is caused by different factors: (1) Iron deficiency anaemia: Due to lack of iron. (2) Thalassaemia: Genetic disorder affecting globin production. (3) Anaemia of chronic disease: Caused by inflammation reducing iron availability. (4) Sideroblastic anaemia: Defective haem synthesis leads to iron buildup in red blood cells

Anaemia of chronic disease is a reduction of red blood cell production in response to chronic disease. What are some causes of this type of anaemia?

(1) Chronic infections (eg. tuberculosis, HIV, and osteomyelitis) (2) Malignancies (eg. Leukaemia, lymphoma, and solid tumours) (3) Autoimmune diseases (eg. rheumatoid arthritis, systemic lupus erythematosus) (4) IBD

Pathophysiology of anaemia of chronic disease

Chronic disease raises IL-6, increasing hepcidin, which blocks iron absorption by inhibiting ferroportin. This leads to anaemia despite normal iron stores. In ACD, ferritin is normal/raised, TIBC is low, and serum iron is normal/low

A 62-year-old woman who is being treated for colorectal cancer attends an oncology follow-up appointment. Her past medical history includes hypothyroidism, rheumatoid arthritis and type 2 diabetes. She says she feels better after having surgery last month but still feels very fatigued and becomes easily breathless. On further questioning, the patient denies having a cough, haemoptysis, or any other symptoms. Her doctor requests repeat blood tests which show she has a normocytic anaemia and thrombocytosis. What are the patient’s iron studies most likely to show?

Low serum iron, high ferritin and low transferrin saturation

Ferritin is a test that shows what?

Relative total body iron stores. A serum ferritin level below 30 micrograms/L confirms a diagnosis of iron deficiency anaemia

Iron deficiency anaemia in patients >60y should prompt what?

suspicion colonic malignancy until proven otherwise and prompt FIT testing and subsequent 2 week wait referral

NICE Guidance now recommends faecal immunochemical testing (FIT) to guide referral for suspected colorectal cancer in adults. Who qualifies?

(1) With an abdominal mass. (2) With a change in bowel habit. With iron-deficiency anaemia. (3) Aged 40 years and over with unexplained weight loss and abdominal pain.

The patient presents with koiloncyhia, "spooning" of the nails. What does this suggest she has?

Iron deficiency anaemia

When would a 2-week-wait colonoscopy be referred?

>10 mcg. Refers to more than 10 micrograms of haemoglobin per gram of faeces

A 20-year-old woman presents to her GP with tiredness and pallor. She has had no changes to her weight, no cold intolerance nor low mood. She eats a varied diet which includes meat and has had no change to her appetite. On further questioning, she reports long heavy periods and often has to use both tampons and sanitary towels to prevent leakage. She has no past medical history and takes no regular medications. Based on the most likely diagnosis, what is the anticipated results of a full blood count?

Low haemoglobin, low mean cell volume

A 35-year-old female with iron deficiency anaemia has been treated with iron supplements for 3 months without significant improvement in her haemoglobin level. What is the next step in management?

Starting an additional work-up for the underlying cause of iron deficiency anaemia

Oral iron supplements, commonly used to treat iron deficiency anaemia, can reduce the absorption of what drug when taken together? What should be done instead?

Levothyroxine =Take four hours before or after Levothyroxine

A 35-year-old female with a background of coeliac disease recently started daily ferrous fumarate iron tablets for iron deficiency anaemia. She presented to the medical clinic three weeks later, complaining of constipation and bloating. She never had any surgeries in the past and does not report any blood loss. Bloods show: - Haemoglobin (Hb): 90 g/L (normal 130–175 g/L) - Platelets: 150 x109/mL (normal 150–400 x109/mL) - Potassium: 4.7 mmol/L (normal 3.5-5.0 mmol/L) - Sodium: 137 mmol/L (normal 137–144 mmol/L) - Urea: 6.9 mmol/L (normal 2.5-7.0 mmol/L) - Creatinine: 98 μmol/L (normal 60-100 μmol/L) Before switching to intravenous iron, strategies such as what could improve tolerance?

(1) Increasing the interval to every other day (2) Adding bulk-forming laxatives

What do iron studies show in iron deficiency anaemia?

Serum iron is low Ferritin is low Total iron binding capacity is high

How is Sideroblastic anaemia distinguished?

high serum ferritin and iron levels

Examples of haem deficiency

1. Sideroblastic anaemia 2. Anaemia of chronic disease 3. Iron deficiency Anaemia

Example of Globin deficiency

Thalassaemia

What is the difference between iron deficiency and anaemia of chronic disease when it comes to (1) Serum iron (2) Transferrin (3) Transferrin saturation % (4) Ferritin (5) MCV

Iron deficiency (1) reduced (2) normal or increased (3) reduced (4) reduced (5) reduced (can be normal) Anaemia of chronic disease (1) reduced (2) normal or reduced (3) reduced (4) normal or increased (5) normal (can be reduced)

Low serum iron High transferrin (or TIBC) Low ferritin Describes what?

Iron Deficiency Anemia

High serum iron Low or normal transferrin (TIBC) High ferritin Describes what?

Sideroblastic Anemia

Low serum iron Low transferrin (or TIBC) Normal or high ferritin Describes what?

Anaemia of chronic disease

All people with iron deficiency anaemia should be screened for

coeliac disease = Anti-transglutaminase antibodies

What results indicate iron deficiency anaemia?

↓ Ferritin ↑ total iron-binding capacity ↓ serum iron ↓ transferrin saturation