pt 11

Question 1

What was Mary’s outcome after treatment?

Answer 1

After steroids, IVIg and splenectomy, she maintained a normal platelet count and remained well at 2-year follow-up.

Question 2

How does this case study exercise benefit medical students?

Answer 2

Integrates factual knowledge with clinical reasoning, stimulating critical thinking for real-world application.

Question 3

What four processes comprise normal haemostasis?

Answer 3

Vasoconstriction of injured vessels, platelet plug formation, blood coagulation (fibrin mesh), and fibrinolysis (clot removal).

Question 4

How do platelets contribute to early haemostasis?

Answer 4

They adhere to exposed collagen, become activated (release granules), and aggregate to form the initial haemostatic plug.

Question 5

Which enzyme is the key rate-limiting factor in the coagulation cascade?

Answer 5

Thrombin (factor IIa).

Question 6

Which clotting factors require vitamin K for synthesis?

Answer 6

Factors II, VII, IX, and X.

Question 7

Where are most clotting factors synthesized?

Answer 7

In the liver.

Question 8

What triggers the intrinsic vs. extrinsic coagulation pathways?

Answer 8

Intrinsic: contact with damaged endothelium; Extrinsic: release of tissue factor (III) from injured tissues.

Question 9

What is the final common pathway of coagulation?

Answer 9

Activation of factor X → prothrombin (II) → thrombin (IIa) → fibrinogen (I) → fibrin (Ia) → stable clot with factor XIII.

Question 10

What role does plasmin play in haemostasis?

Answer 10

It degrades fibrin, dissolving clots (fibrinolysis).

Question 11

Why is an internal control plasma run alongside patient samples in coagulation tests?

Answer 11

Lab‐to‐lab variability makes the patient‐vs‐control difference more reliable than absolute ranges.

Question 12

What anticoagulants are used for full blood count vs. clotting studies?

Answer 12

EDTA for full blood count; sodium citrate for coagulation tests.

Question 13

Why must platelet-poor plasma (PPP) be used for most coagulation assays?

Answer 13

Platelets can activate clotting in vitro, skewing results; PPP avoids this.

Question 14

Name three routine laboratory tests of haemostatic function.

Answer 14

Bleeding time, activated partial thromboplastin time (APTT), prothrombin time (PT).

Question 15

What does an isolated prolongation of APTT indicate?

Answer 15

A defect in the intrinsic (or common) pathway (factors XII, XI, IX, VIII, X, V, II, I).

Question 16

What does an isolated prolongation of PT indicate?

Answer 16

A defect in the extrinsic (or common) pathway (factors VII, X, V, II, I).

Question 17

What specialized tests follow an abnormal routine coagulation screen?

Answer 17

50:50 correction studies, individual factor assays, and inhibitor studies.

Question 18

What distinguishes primary vs. secondary haemostatic disorders?

Answer 18

Primary involves vessels/platelets (mucocutaneous bleeding); Secondary involves clotting factors (deep tissue/joint bleeds).

Question 19

Define thrombocytopenia and its three main mechanisms.

Answer 19

Platelet count <150×10⁹/L due to ↓ production, ↑ destruction, or sequestration in spleen.

Question 20

At what platelet counts do bleeding risks rise?

Answer 20

<50×10⁹/L: bleeding after trauma; <20×10⁹/L: spontaneous bleeding.

Question 21

List common causes of decreased platelet production.

Answer 21

Aplastic anaemia, megaloblastic anaemia, marrow infiltration (malignancy, metastases).

Question 22

List common causes of increased platelet destruction.

Answer 22

Immune (ITP, SLE), alloimmune (neonatal/post-transfusion), DIC, TTP, certain drugs/infections.

Question 23

What is idiopathic thrombocytopenic purpura (ITP)?

Answer 23

Autoimmune platelet destruction with antiplatelet antibodies and splenic clearance.

Question 24

How does childhood ITP differ from adult ITP?

Answer 24

Childhood ITP is acute and self-limiting; adult ITP is often chronic, female-predominant, and associated with other autoimmune diseases.

Question 25

What are first- and second-line treatments for adult ITP?

Answer 25

1st: corticosteroids (± IVIG); 2nd: splenectomy (± immunosuppression, thrombopoietin agonists).

Question 26

Which inherited disorders most commonly cause severe bleeding?

Answer 26

Haemophilia A (factor VIII), Haemophilia B (factor IX), and von Willebrand disease.

Question 27

What is the inheritance pattern of haemophilia A and B?

Answer 27

X-linked recessive, primarily affecting males.

Question 28

How does factor VIII activity correlate with haemophilia A severity?

Answer 28

<1%: spontaneous bleeding; 1–5%: bleeding after minor trauma; >5%: asymptomatic.

Question 29

Why is bleeding in haemophilia typically deep (joints, muscles)?

Answer 29

Factor deficiencies impair fibrin clot formation in high-stress tissues rather than superficial vessels.

Question 30

What laboratory pattern is seen in haemophilia A?

Answer 30

Prolonged APTT; normal PT and bleeding time; low factor VIII levels.

Question 31

What is von Willebrand disease and its effects?

Answer 31

vWF deficiency → impaired platelet adhesion and reduced factor VIII stability; autosomal trait with multiple mutations.

Question 32

Name three acquired causes of coagulation factor deficiencies.

Answer 32

Vitamin K deficiency/warfarin therapy, liver disease, and disseminated intravascular coagulation (DIC).

Question 33

Why does liver disease impair haemostasis?

Answer 33

↓ synthesis of clotting factors, vitamin K malabsorption, thrombocytopenia (hypersplenism), and dysfunctional fibrinogen/platelets.

Question 34

How does vitamin K deficiency arise in newborns?

Answer 34

Lack of gut flora to produce vitamin K; leads to haemorrhagic disease of the newborn.

Question 35

What precautions are critical during coagulation sample collection?

Answer 35

Use correct anticoagulant, gentle mixing, prompt processing (<2–4 h), and avoid platelet activation.

Question 36

What are key pre-analytical and analytical errors in coagulation testing?

Answer 36

Pre-analytical: wrong tube, contamination, delays; Analytical: outdated/poor reagents or controls, temperature errors.

Question 37

What are the three primary synthetic and metabolic functions of the liver?

Answer 37

Synthesis/metabolism of carbohydrates, lipids, proteins & drugs; metabolism/excretion of bilirubin and bile acids; production of plasma proteins (e.g., albumin).

Question 38

Why is the liver vulnerable to a wide variety of insults?

Answer 38

It has a dual blood supply (hepatic artery + portal vein), exposing it to systemic and gut-derived toxins, microbes, and metabolic stresses.

Question 39

Name four major primary liver diseases covered in the lecture.

Answer 39

Viral hepatitis, alcoholic liver disease, nonalcoholic fatty liver disease (NAFLD), hepatocellular carcinoma.

Question 40

What are the leading causes of liver disease in Western countries vs. elsewhere?

Answer 40

West: alcohol and hepatitis C; elsewhere: hepatitis B (decreasing due to vaccination).

Question 41

Define jaundice and its biochemical threshold.

Answer 41

Yellowing of sclera/skin due to serum bilirubin > 50 µmol/L (normal ≈ 17 µmol/L).

Question 42

What distinguishes pre-hepatic (haemolytic) jaundice?

Answer 42

↑ unconjugated bilirubin, normal ALP & transaminases; due to excessive RBC breakdown.

Question 43

What is Gilbert’s syndrome?

Answer 43

A congenital ↓ UDP-glucuronyl transferase activity → mild ↑ unconjugated bilirubin with otherwise normal liver tests.

Question 44

How is cholestatic jaundice classified?

Answer 44

Intrahepatic (impaired bile excretion) vs. extrahepatic (mechanical obstruction distal to canaliculi).

Question 45

Which lab patterns suggest extrahepatic bile duct obstruction?

Answer 45

Markedly ↑ ALP, moderate ↑ ALT/AST; ultrasound shows dilated bile ducts.

Question 46

Outline the normal pathway of bilirubin metabolism.

Answer 46

RBC → heme → biliverdin → unconjugated bilirubin (albumin‐bound) → hepatocyte uptake → UDPGT conjugation → bile → gut (urobilinogen) → re-uptake (enterohepatic) or excretion (stercobilin, urobilin).

Question 47

What pattern of bilirubin is seen in hepatocellular (mixed) jaundice?

Answer 47

Both unconjugated and conjugated bilirubin ↑ due to hepatocyte damage leaking both forms.

Question 48

What are the histological hallmarks of acute hepatitis?

Answer 48

Hepatocyte necrosis and mixed inflammatory cell (lymphocyte, macrophage) infiltration.

Question 49

Name four non‐viral causes of acute hepatitis.

Answer 49

Alcohol, drugs (e.g., isoniazid), pregnancy-related cholestasis, nonviral infections (e.g., Toxoplasma).

Question 50

Which enzyme is the most specific indicator of acute hepatic injury?

Answer 50

ALT (elevated in hepatocyte damage; AST less specific as it’s also in muscle).