Von Willebrand Disease

Overview

vWD = most common hereditary coagulation disorder. Qualitative/quantitative vWF defect. ~1:1000, both sexes.

vWF vs Factor VIII

vWF stabilises factor VIII too — so vWF deficiency also lowers factor VIII.

Clinical features

Mucosal/mucous membrane bleeding + easy bruising, wound bleeding — platelet-type pattern, not deep joint/muscle bleeds like haemophilia.

Three types:

1. Type I (commonest) — mild-moderate ↓vWF (~50%), release impaired
2. Type II (less common) — normal levels, functionally defective
3. Type III (rare, severe) — no detectable vWF, low factor VIII too

Lab findings

• Prolonged bleeding time
• Normal platelet count
• ↓Plasma vWF (ristocetin cofactor assay)
• Defective ristocetin-induced platelet aggregation (classic test)
• ↓Factor VIII activity (secondary)

Treatment

Cryoprecipitate or factor VIII concentrates.

Clinical relevance

Bleeding pattern tells you which system failed — mucosal/skin bleeding points to vWD (platelet-adhesion problem), deep joint/muscle bleeds point to haemophilia (coagulation-factor problem). Autosomal dominant + both sexes affected (vWD) vs X-linked recessive + males only (haemophilia A) is the other quick differentiator. Low factor VIII in vWD can look like mild haemophilia on that test alone — ristocetin aggregation test + normal platelet count + prolonged bleeding time is what correctly points to vWD instead.

Overview

Von Willebrand disease (vWD) is the most common hereditary coagulation disorder, from a qualitative or quantitative defect in von Willebrand factor (vWF), with an estimated incidence of about 1 in 1,000 individuals of either sex — considerably more common than hameophilia A, though usually far milder in its typical (Type 1) form.

Von Willebrand Factor and Factor VIII: A Contrasted Pair

vWF forms the larger component of the circulating factor VIII–vWF complex; the two components travel together and cooperate functionally, but differ fundamentally:

vWF also stabilises factor VIII in the circulation; consequently, vWF deficiency produces a secondary reduction in factor VIII activity, which is why vWD’s laboratory picture includes reduced factor VIII alongside its primary platelet-adhesion defect.

Clinical Features

Spontaneous bleeding from mucous membranes and excessive bleeding from wounds — a pattern dominated by platelet-type bleeding (mucosal, cutaneous) rather than the deep muscle/joint bleeding characteristic of haemophilia.

Three Major Types

1. Type I (most common) — mild-moderate quantitative reduction in plasma vWF (~50% activity); synthesis is normal, but multimer release is impaired.
2. Type II — less common; vWF levels normal or near-normal but functionally defective — several subtypes exist based on which vWF multimers are affected (loss of high-molecular-weight multimers, the most functionally active form).
3. Type III — extremely rare, most severe; no detectable vWF activity, with sufficiently low factor VIII levels to produce features resembling haemophilia.

Laboratory Findings

• Prolonged bleeding time (reflects the platelet-adhesion defect).
• Normal platelet count.
• Reduced plasma vWF concentration (assayed directly, or functionally via the ristocetin cofactor assay).
• Defective platelet aggregation with ristocetin — ristocetin normally promotes vWF-mediated binding between platelet glycoprotein Ib and vWF, producing agglutination; this response is impaired in vWD and is the classic diagnostic bioassay.
• Reduced factor VIII activity (secondary to loss of vWF’s stabilising effect).

Treatment

Bleeding episodes are managed with cryoprecipitate or factor VIII concentrates (which contain vWF), replacing the deficient/dysfunctional factor.

Clinical Relevance

• The bleeding pattern itself is diagnostically informative: mucosal/cutaneous bleeding (vWD, a platelet-adhesion disorder) versus deep haemarthroses/muscle haematomas (haemophilia, a coagulation-factor disorder) reflects the different physiological roles of vWF (platelet plug formation) versus factor VIII (coagulation cascade amplification) — the clinical picture is a direct readout of which step of haemostasis is defective.
• The autosomal dominant inheritance of vWD, affecting both sexes, versus the X-linked recessive inheritance of haemophilia A, affecting almost exclusively males, is a key distinguishing feature when family history and sex distribution are considered in a bleeding-disorder workup.
• Reduced factor VIII activity in vWD (from loss of vWF’s stabilising function) can superficially mimic mild haemophilia A on a factor VIII assay alone — the ristocetin cofactor/platelet aggregation test and normal platelet count with prolonged bleeding time are what correctly redirect the diagnosis toward vWD.

No Rendered Diagram for This Topic

Von Willebrand disease is a classification-and-comparison topic (Type I/II/III; vWF vs factor VIII), not a multi-step mechanism — a rendered process diagram would not add anything beyond the comparison table already in notes.md.

Hand-Draw Suggestion

Draw the vWF–factor VIII comparison table from notes.md by hand as a quick two-column recall aid (Gene location / Inheritance / Site of synthesis / Main function), and a small three-row box for Type I / Type II / Type III with one defining phrase each (↓amount / functionally defective / absent).