essay 28 - hemostatic abnormalities - hemorrhagic diathesis

what is hemorrhagic diathesis

• an increased tendency to bleed due to defects in one or more components of the hemostatic system:

1. vascular wall (blood vessel integrity)

2. platelets (number or function)

3. coagulation cascade (clotting factors)

describe coagulation abnormalities

• cause = deficiencies or dysfunctions of clotting factors → defective fibrin clot formation → prolonged bleeding

• such disorders = acquired coagulation abnormality and haemophilia (inherited coagulation abnormality)

describe acquired coagulation abnromality (type of coagulation abnormality)

• vit k deficiency = e.g malnutrition = vitamin k is required for synthesis of factors II, VII, IX, X

• liver damage = e.g cirrhosis = most clotting factors are made in the liver

describe hemophilia (type of coagulation abnormality)

• genetic bleeding disorder where specific clotting factors are missing or dysfunctional → weak/slow clot formation → recurrent and prolonged bleeding

• inheritance = most are x-linked recessive
  - men (XY) with the gene develop disease
  - women (XX) are usually carriers, sometimes with mild symptoms

• complications= recurrent joint bleeding → hemophilic athropathy (fibrosis, cartilage destruction)

types of hemophilia

severities of hemophilia

describe platelet abnormalities

• causes =

• decreased production = bone marrow suppression (chemotherapy, HIV viral infection, vitamin B12 deficiency)

• increased destruction = immune thrombocytopenic purpura (ITP), disseminated intravascular coagulation (DIC), thrombotic thrombocytopenic purpura (TTP)

• splenic sequestration (hypersplenism)

• pseudothromocytopenia (artifact in vitro → clumped platelets)
  

qualitative plateles fucntion disorders

• hereditary = glanzmann thrombasthenia (defective aggregation, glycoprotein IIb/IIIa defect)

• acquired = drugs (asprin, NSAIDs → inhibit platelet cyclooxygenase)

vascular wall abnormalities

• causes = structural or functional defects in blood vessel walls → increased fragilities

• Types:

1. hereditary =

• Rendu-Osler-Weber disease = a rare genetic disorder causing malformations of blood vessels, particularly arteriovenous malformations (AVMs), which leads to excessive bleeding, especially nosebleeds, red spots on skin and anemia

1. acquired:

• Henoch-Scholein Purpura (HSP)
  - small vessel IgA-mediated vasculitis
  - common in children (2-8 years), often after upper respiratory infection
  symptoms + palpable purpura (legs), arthritis (knees, ankles), abdominal pain, GI bleeding, renal involvement (haematuria, proteinuria)

• vitamin C deficiency (scurvy → defective collagen in vessel walls → fragile capillaries)