Before a planned cholecystectomy, a 29-year-old woman with frequent nosebleeds and heavy periods has a PT of 26.4 s (reference 11.0-13.5 s; INR 2.3) and an APTT of 31 s (reference 25-35 s). She takes no medicines, eats a normal diet and has normal liver tests. Thrombin time and fibrinogen are normal, and the PT corrects to 12.9 s in a 1:1 mix with normal plasma. Factor activities (reference 50-150%): II 96%, V 104%, VII 4%, IX 98%, X 91%. The PT is unchanged 24 hours after intravenous vitamin K. The most likely diagnosis is:

Inherited factor VII deficiency

A 6-week-old breastfed baby who did not receive vitamin K at birth has an intracranial bleed. PT and aPTT are both prolonged, and the platelet count is 320 × 10^3/µL (320 × 10^9/L). The most likely cause is:

Neonatal alloimmune thrombocytopenia

A 34-year-old woman has gum bleeding and blood in her urine, and takes no prescribed medicines. Her INR is 7.8, the aPTT is prolonged, factors II, VII, IX and X are low, and factor V and fibrinogen are normal. After vitamin K her INR falls, but within days it rises again. The most likely cause is:

Long-acting rodenticide (superwarfarin)

Factor X deficiency from amyloidosis

Disseminated intravascular coagulation

A man with hemophilia A and a woman who is not a carrier have children. Which outcome is expected?

All daughters carriers; no sons affected

Half of all the children affected

All sons affected; no daughters carriers

Half the sons affected; half the daughters carriers

Disease states: factor deficiencies (acquired and hereditary)

13 ASCP MLS practice questions on Disease states: factor deficiencies (acquired and hereditary), part of Hematology. The first 13 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
Before a planned cholecystectomy, a 29-year-old woman with frequent nosebleeds and heavy periods has a PT of 26.4 s (reference 11.0-13.5 s; INR 2.3) and an APTT of 31 s (reference 25-35 s). She takes no medicines, eats a normal diet and has normal liver tests. Thrombin time and fibrinogen are normal, and the PT corrects to 12.9 s in a 1:1 mix with normal plasma. Factor activities (reference 50-150%): II 96%, V 104%, VII 4%, IX 98%, X 91%. The PT is unchanged 24 hours after intravenous vitamin K. The most likely diagnosis is:
1. ACovert warfarin ingestion
2. BEarly liver synthetic failure
3. CInherited factor VII deficiency
4. DEarly vitamin K deficiency
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Answer: C · Inherited factor VII deficiency
An isolated prolonged PT that corrects on mixing points to a deficiency in the extrinsic pathway, and the assays show that only factor VII is low. Vitamin K deficiency and warfarin lower factor VII first because of its short half-life of about 4 to 6 hours, but factors II, IX and X would also be reduced and the PT would shorten after vitamin K. Liver failure lowers factor V as well, and her liver tests are normal. Inherited factor VII deficiency is a rare autosomal recessive disorder in which bleeding matches the factor level only loosely. Recombinant factor VIIa is used to cover surgery.
- A: Warfarin lowers all the vitamin K-dependent factors, not factor VII alone, and vitamin K would reverse it.
- B: Liver failure also lowers factor V, and her liver tests are normal.
- D: Vitamin K deficiency would also lower II, IX and X, and the PT would shorten after vitamin K.
Question 2 · Medium
A 6-week-old breastfed baby who did not receive vitamin K at birth has an intracranial bleed. PT and aPTT are both prolonged, and the platelet count is 320 × 10^3/µL (320 × 10^9/L). The most likely cause is:
1. ASevere hemophilia A
2. BFactor XIII deficiency
3. CNeonatal alloimmune thrombocytopenia
4. DVitamin K deficiency bleeding
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Answer: D · Vitamin K deficiency bleeding
Newborns have low vitamin K stores because little crosses the placenta, breast milk contains little, and the gut is not yet colonized by bacteria that make it. Late vitamin K deficiency bleeding appears at 2 to 12 weeks, mostly in breastfed babies who missed prophylaxis, and often causes intracranial hemorrhage. Factors II, VII, IX and X fall, so both the PT and the aPTT are prolonged. A single intramuscular dose of vitamin K at birth prevents it.
- A: Hemophilia A prolongs the aPTT but not the PT.
- B: Factor XIII deficiency leaves the PT and aPTT normal.
- C: Alloimmune thrombocytopenia gives a low platelet count with normal clotting times.
Question 3 · Medium
When vitamin K is lacking, the PT is usually the first test to become prolonged. Which factor's short half-life explains this?
1. AFactor IX
2. BFactor II (prothrombin)
3. CFactor VII
4. DFactor X
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Answer: C · Factor VII
Factor VII has the shortest half-life of the vitamin K-dependent factors, about 4 to 6 hours. When carboxylation stops it falls first, and because it is measured only by the PT, the PT lengthens before the aPTT. Factor IX lasts about a day, factor X about 40 hours and prothrombin about 60 to 72 hours. This is also why the INR rises within the first days of warfarin, before full anticoagulation is reached.
- A: Factor IX lasts about a day and affects the aPTT, not the PT.
- B: Prothrombin has the longest half-life of these factors, about 60 to 72 hours.
- D: Factor X lasts about 40 hours and affects both the PT and the aPTT.
Question 4 · Hard
A 34-year-old woman has gum bleeding and blood in her urine, and takes no prescribed medicines. Her INR is 7.8, the aPTT is prolonged, factors II, VII, IX and X are low, and factor V and fibrinogen are normal. After vitamin K her INR falls, but within days it rises again. The most likely cause is:
1. AAcute liver failure
2. BFactor X deficiency from amyloidosis
3. CLong-acting rodenticide (superwarfarin)
4. DDisseminated intravascular coagulation
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Answer: C · Long-acting rodenticide (superwarfarin)
Low factors II, VII, IX and X with a normal factor V point to vitamin K deficiency or a vitamin K antagonist rather than liver failure. A quick response to vitamin K that does not last suggests a long-acting antagonist such as brodifacoum, whose half-life is weeks rather than the roughly 40 hours of warfarin. Treatment is high-dose oral vitamin K for weeks to months, guided by repeated INR checks. A serum assay for these compounds confirms the diagnosis.
- A: Liver failure lowers factor V as well.
- B: Amyloid-associated deficiency lowers factor X alone.
- D: DIC lowers fibrinogen, factor V and the platelet count.
Question 5 · Medium
A man with hemophilia A and a woman who is not a carrier have children. Which outcome is expected?
1. AHalf of all the children affected
2. BAll daughters carriers; no sons affected
3. CAll sons affected; no daughters carriers
4. DHalf the sons affected; half the daughters carriers
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Answer: B · All daughters carriers; no sons affected
The F8 gene is on the X chromosome. An affected father passes his only X chromosome, carrying the variant, to every daughter, so all daughters are obligate carriers. He passes his Y chromosome to every son, so no son inherits hemophilia from him. His daughters should have their factor VIII measured, because some carriers have low levels.
- A: X-linked inheritance does not give a 50% risk to every child.
- C: Sons receive their father's Y chromosome, not his X.
- D: This pattern applies when the mother is a carrier and the father is unaffected.
Question 6 · Medium
A 30-year-old man of Ashkenazi Jewish descent bleeds for two days after a tooth extraction. PT is normal, aPTT is prolonged, and factors VIII and IX are normal. Which factor is most likely deficient?
1. AFactor XIII
2. BFactor XI
3. CFactor XII
4. DFactor VII
Answer and explanation in LearnFree account
Question 7 · Hard
A 24-year-old woman whose father has severe hemophilia A has bled after minor procedures since childhood. Her mother's family has no bleeding history. Factor VIII is 25% (0.25 IU/mL), and VWF antigen and activity are normal. The best explanation is:
1. AShe inherited hemophilia A from both parents
2. BShe has an acquired factor VIII autoantibody
3. CShe has type 3 von Willebrand disease
4. DShe is a carrier with skewed X inactivation
Answer and explanation in LearnFree account
Question 8 · Hard
A 10-day-old boy bleeds from his umbilical stump. Platelet count, PT, aPTT, thrombin time and fibrinogen are all normal. Which test should be done next?
1. AQuantitative factor XIII activity assay
2. BFactor VII activity assay
3. CPlatelet aggregation studies
4. DFactor VIII activity assay
Answer and explanation in LearnFree account
Question 9 · Easy
Vitamin K is required for which step in the synthesis of factors II, VII, IX and X?
1. ACleavage of the activation peptide
2. BHydroxylation of lysine residues
3. CGamma-carboxylation of glutamate
4. DPhosphorylation of serine residues
Answer and explanation in LearnFree account
Question 10 · Easy
Hemophilia B is an inherited deficiency of factor:
1. AXI
2. BXIII
3. CVIII
4. DIX
Answer and explanation in LearnFree account
Question 11 · Medium
Which bleeding pattern is most typical of severe hemophilia A?
1. AJoint and deep muscle bleeds
2. BBleeding from the umbilical stump
3. CPetechiae and bleeding from gums
4. DNosebleeds and heavy menstrual flow
Answer and explanation in LearnFree account
Question 12 · Hard
The mother of a term newborn boy is a known hemophilia B carrier. His cord blood factor IX is 30% (0.30 IU/mL); the adult reference range is 50-150%. What is the best interpretation?
1. AReport it as normal with no further testing
2. BDiagnose mild hemophilia B at once
3. CTest him for a factor IX inhibitor
4. DCompare with neonatal ranges and retest him later
Answer and explanation in LearnFree account
Question 13 · Hard
A 60-year-old man with advanced cirrhosis has an INR of 2.3 that does not correct after intravenous vitamin K. Which pattern of factor results is most likely?
1. ALow VIII only; V and VII normal
2. BLow V and VII; VIII normal or high
3. CLow V, VII and VIII together
4. DLow VII only; V and VIII normal
Answer and explanation in LearnFree account

Disease states: factor deficiencies (acquired and hereditary)

A 6-week-old breastfed baby who did not receive vitamin K at birth has an intracranial bleed. PT and aPTT are both prolonged, and the platelet count is 320 × 10^3/µL (320 × 10^9/L). The most likely cause is:

When vitamin K is lacking, the PT is usually the first test to become prolonged. Which factor's short half-life explains this?

A 34-year-old woman has gum bleeding and blood in her urine, and takes no prescribed medicines. Her INR is 7.8, the aPTT is prolonged, factors II, VII, IX and X are low, and factor V and fibrinogen are normal. After vitamin K her INR falls, but within days it rises again. The most likely cause is:

A man with hemophilia A and a woman who is not a carrier have children. Which outcome is expected?

A 30-year-old man of Ashkenazi Jewish descent bleeds for two days after a tooth extraction. PT is normal, aPTT is prolonged, and factors VIII and IX are normal. Which factor is most likely deficient?

A 24-year-old woman whose father has severe hemophilia A has bled after minor procedures since childhood. Her mother's family has no bleeding history. Factor VIII is 25% (0.25 IU/mL), and VWF antigen and activity are normal. The best explanation is:

A 10-day-old boy bleeds from his umbilical stump. Platelet count, PT, aPTT, thrombin time and fibrinogen are all normal. Which test should be done next?

Vitamin K is required for which step in the synthesis of factors II, VII, IX and X?

Hemophilia B is an inherited deficiency of factor:

Which bleeding pattern is most typical of severe hemophilia A?

The mother of a term newborn boy is a known hemophilia B carrier. His cord blood factor IX is 30% (0.30 IU/mL); the adult reference range is 50-150%. What is the best interpretation?

A 60-year-old man with advanced cirrhosis has an INR of 2.3 that does not correct after intravenous vitamin K. Which pattern of factor results is most likely?