Thrombotic microangiopathy: the kidney
- Lesion
Endothelial injury fills glomerular capillaries and arterioles with platelet-fibrin thrombi, causing acute kidney injury with hemolysis.
What it is
This page covers the kidney lesion; the systemic picture of TTP and HUS is on the red cell pages. In thrombotic microangiopathy, injured endothelium in small vessels leads to platelet and fibrin thrombi, red cell fragmentation and thrombocytopenia. The kidney is hit hardest in hemolytic uremic syndrome: typical HUS from Shiga toxin of E. coli O157:H7 or Shigella dysenteriae type 1, and atypical HUS from defects in complement regulation. TTP, from ADAMTS13 deficiency, involves the brain more often. Malignant hypertension, scleroderma, antiphospholipid syndrome, preeclampsia, drugs and transplantation produce the same lesion.
Structure
- Acute: glomerular capillaries thickened by swollen endothelium and subendothelial fluffy material, with fibrin-platelet thrombi.
- Arterioles and small arteries show thrombi, fibrinoid necrosis and mucoid intimal thickening; severe cases give cortical necrosis.
- Chronic: double contours of the GBM, onion-skin arteriolar hyperplasia and glomerular sclerosis.
- IF shows fibrin in glomeruli and vessels but no immune deposits.
Thrombotic microangiopathies with kidney injury
| Form | Cause | Kidney involvement |
|---|---|---|
| Typical (Shiga toxin) HUS | E. coli O157:H7, Shigella dysenteriae; toxin injures endothelium | Severe acute kidney injury, mostly in children; usually recovers |
| Atypical (complement-mediated) HUS | Inherited or acquired defects in complement regulation | Recurrent kidney failure, often relapses after transplant |
| TTP | ADAMTS13 deficiency, autoimmune or inherited | Usually milder kidney injury; brain more affected |
| Secondary forms | Scleroderma, malignant hypertension, antiphospholipid antibodies, preeclampsia, drugs, transplant | Arteriolar lesions dominate |
Clinical notes
- A child with bloody diarrhea who becomes pale and oliguric with petechiae: think of Shiga-toxin HUS.
- Antibiotics in Shiga-toxin E. coli infection may increase toxin release; management is supportive.
- In scleroderma renal crisis, sudden hypertension and kidney failure with this lesion respond to ACE inhibition.
Test yourself
Think of the answer, then tap the question to see it.
How does Shiga toxin cause HUS?
It binds the glycolipid Gb3 on glomerular endothelium, injures the cells and triggers thrombi in glomerular capillaries.
What defect underlies atypical HUS?
Uncontrolled activation of the alternative complement pathway, from variants or antibodies affecting factor H, factor I, CD46 or C3.
What does the kidney biopsy show in thrombotic microangiopathy?
Fibrin-platelet thrombi in glomerular capillaries and arterioles, swollen endothelium, without immune deposits.
Elsewhere in DurgiPedia
Connections
Microorganisms2
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Hemolytic-uremic syndrome: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025); Thrombotic thrombocytopenic purpura: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.