Young patient+ anaemia+ repeated blood transfusion but no improvement+ bud chiary syndrome+ hepatosplenomegaly Dx ki
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"paroxysmal nocturnal hemoglobinuria" AND "Budd-Chiari"
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Diagnosis: Paroxysmal Nocturnal Haemoglobinuria (PNH)
This is a classic PNH presentation. Here is the full breakdown:
Why PNH Fits Every Clue
| Clinical Feature | PNH Explanation |
|---|---|
| Young patient | Peak age 10-50 years; mean diagnosis ~34 years |
| Anaemia | Chronic intravascular haemolysis (hallmark of the disease) |
| Repeated transfusions, no improvement | Haemolysis is ongoing and complement-driven; transfusions give temporary relief but do not address the underlying mechanism |
| Budd-Chiari syndrome | Hepatic vein thrombosis - occurs in unusual sites; Budd-Chiari without liver disease should always raise suspicion of PNH |
| Hepatosplenomegaly | Consequence of hepatic vein obstruction (Budd-Chiari) and extramedullary haematopoiesis |
Pathophysiology (in short)
- Acquired somatic mutation in the PIG-A gene (on the short arm of the X chromosome) in a pluripotent haematopoietic stem cell
- PIG-A encodes an enzyme essential for synthesis of GPI (glycosylphosphatidylinositol) anchors
- Loss of GPI anchors means loss of complement regulatory proteins CD55 (decay-accelerating factor - inhibits C3 convertase) and CD59 (membrane inhibitor of reactive lysis - blocks the membrane attack complex)
- Red cells without CD55/CD59 are destroyed by uncontrolled complement activation → intravascular haemolysis
- Thrombosis: CD59-deficient platelets externalize phosphatidylserine, creating prothrombinase complexes → hypercoagulable state → thrombosis in unusual sites (hepatic veins, cerebral veins, abdominal veins)
As Harrison's states: "When thrombosis affects the hepatic vein, it may produce acute hepatomegaly and ascites, i.e., a full-fledged Budd-Chiari syndrome, which, in the absence of liver disease, ought to raise the suspicion of PNH." - Harrison's Principles of Internal Medicine 22E
Triad of PNH (Classic)
- Haemolytic anaemia (intravascular)
- Pancytopenia (bone marrow failure component)
- Venous thrombosis at unusual sites (especially hepatic veins)
Why Transfusions Don't Help
Blood transfusions are ineffective because:
- The underlying complement-mediated destruction continues unabated
- Transfused normal RBCs also get destroyed (especially with whole blood transfusion which can trigger bouts of haemolysis)
- Iron is lost through chronic haemoglobinuria and haemosiderinuria, causing iron deficiency that compounds the anaemia
Investigations to Confirm
| Test | Finding |
|---|---|
| Flow cytometry (gold standard) | Absent/reduced CD55 and CD59 on RBCs and granulocytes; absent FLAER (fluorescent aerolysin) |
| LDH | Markedly elevated (in the thousands) |
| Haptoglobin | Undetectable |
| Reticulocyte count | Elevated |
| Urine | Haemoglobinuria, haemosiderinuria |
| Direct Coombs (DAT) | Negative (not immune-mediated) |
| Ham's test (acid serum test) | Historically used; now replaced by flow cytometry |
| Bone marrow | May be hypercellular (erythroid hyperplasia) or hypocellular |
Treatment
- Eculizumab (anti-C5 complement inhibitor) - the first targeted therapy; dramatically reduces haemolysis and thrombosis
- Ravulizumab - longer-acting anti-C5 inhibitor (dosing every 8 weeks)
- Anticoagulation for thrombotic episodes
- Allogeneic haematopoietic stem cell transplantation - the only potential cure
- Supportive: folic acid, iron replacement (if deficient), vaccinations (N. meningitidis, S. pneumoniae before eculizumab)
Sources: Goldman-Cecil Medicine; Harrison's Principles of Internal Medicine 22E; Henry's Clinical Diagnosis and Management by Laboratory Methods
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