The document describes 3 cases of thrombotic microangiopathy (TMA). Case 1 involves a 22-year-old male presenting with weakness, abdominal pain, and vomiting. Laboratory results show evidence of microangiopathic hemolytic anemia (MAHA). Treatment with steroids and rituximab improved his condition. Case 2 involves a 5-year-old boy with a history of neuroblastoma who developed bloody diarrhea and renal failure. Plasma exchange and dialysis stabilized his condition. Case 3 is a 28-year-old pregnant woman presenting with preeclampsia who developed MAHA. Plasma exchange and steroids improved her symptoms and she had a normal pregnancy outcome after treatment.

1. Thrombotic microangiopathies--- Differential
diagnosis ,Pathogenesis and treatment.
DR Shabir Ahmad Mir
Alsabah Hospital

2. Case 1
• 22 yrs male ,police trainee
• Past History and family history negative.
• Weakness, epigastric pain ,vomiting, headache since 2 days. No fever, no bleeding.
• URTI 5 days back ,received Augmentin and brufen
• Pallor, P 100/min, BP 110/70 ,Temp 37C,No skin rash, No edema ,No neurodeficit, no
organomegaly.
Complete blood count
•WBC 15.46
•HGB 129g/L
•HCT 0.379
•MCV 87.1 fL
•MCH 29.7 pg
•MCHC 340 g/L
•PLT 139
Urea 13.2
Creat 384 Na
137 K 4.4
Glucose 5.5
Amylase 71
T.Bil 38 D.Bil 6
osmolailty 294
CK 237
Chemistry

3. Case 1
Over next 24 hours pt developed oliguria, worsening of renal failure,
Thrombocytopenia and hemolysis—Evidence of MAHA
Complete blood count Urine
•Proteins++
•Blood +++
•Nitrate-Neg
•RBC 2-3
•WBC 0-2
Clincal chemistry
•Total bilirubine 38 umol/L
•Indirect bil 32 D.Bil 6
•Crea 396/712/888 umol/L
Urea 14.3/19.8/23.3 Ca
2.3PO41.21
•Urate 535 CK 237
•Na 137 K 4.6 VBG-WNL
•Amylase 37
•ALT 103 U/L
•LDH 1827 U/L
Coagulation :INR 1 APTT
29 PT 13.7
: Hb 9.6 WBC 12.7 6PLTS
86
N 64 E 1.7%
MCV 86

4. Case 1
He remained hemodynamically stable
Became oliguric and renal failure worsened
Developed mild metabolic acidosis
Lab works showed clear evidence of MAHA
Needs further investigations ?
Treatment options?
Complete blood count Special investigations
HBSAg-negative
HCV Ab-Neg
HIV-negative
Blood c/s-no growth
UrineC/S-No growth
Sputum C/S-No growth
Coombs test-Negative
ANA-Neg dSDNA-Neg
C3-0.85(0.9-1.8) C4-
Normal
Clincal chemistry
•Total bilirubine 63 umol/L
•Indirect bil 42 D.Bil 21
•Crea 946 umol/L Urea 23.
•Urate 544
•Na 138 K 4.1 VBG-HCO3
18
•Heptoglobin 0.08(N 0.3-
2.0)
•ALT95 U/L ALP 57
•LDH 1871 U/L
Coagulation :INR 1 APTT 29
PT 13.7
: Hb 73 WBC 12.47 PLTS 85
N 70 E 2% Retics 3.27
MCV 86
PBF: schistocytes ++
B12,Folate levels--WNL

5. Complexity of the diagnosis: thrombotic microangiopathy (TMA)
• DD:-HUS(aHUS vs STEC-HUS vs pHUS), TTP,others causes of MAHA
• Normal BP, Normal coagulation, Age group, no diarrhea , no neurological
signs.
• Negative septic screen
• Low C3
• Further investigations needed:
• ADAMTS 13 level ,ADAMTS 13 Ab.
• Complement pathway regulators :CFH ,CFI, CFHR,MCP(Membrane co-
Factor protein).
• Complement Activators:CFB,C3.
• Throbomodulin (THBD)-inhibits C3a and C5a.
• Antibody to CFH
• Treatment Modalities:PI, PEX, Steroids,
Eculizimab

6. Treatment and response
• Pulse methyl prednisolone followed by oral prednisolone and
rituximab.
• Dialysis for one week
• Plasmapheresis—14 sessions
Progress: Normalization of hemolysis ,Thrombocytopenia and
Renal functions. On discharge Hb 11.8 PLTs 212 urea 5 creat 80.3
C3/C4-Normal Bil 8 LDH 200
ADAMTS 13 activity more than 15%
ADAMTS 13 Ab—not detected
Follow up: Resumed and completed his training
Normal RFT, CBC, Blood pressure at 1 year
No proteins in urine, RBC 6-8/HPF.

7. Case 2
• 5 yrs syrian boy
• History of Rt Adrenal Neuroblastoma—resected in 2018 and followed by chemo-
radiotherapy.
• 6 months back underwent allogenic bone marrow transplantation
• Not on immuno-supressants
• Presented with bloody diarrhea and abdominal pain managed with Iv fluids and
antibiotics.BP 100/60 HR 100/mt Temp 37.2 No edema, No skin rash
Complete blood count Urine
•Proteins+
•Blood ++
•Nitrate-Neg
•RBC 2-4
•WBC 0-2
Clincal chemistry
•Crea 80 Urea 12 Ca 2.4
PO4 1.21
•Urate 400 CK 237
•Na 136 K 4. VBG-WNL
•Hapltoglobin 0,1 g/L
Coagulation :INR1 APTT 28 PT
13.
: Hb 124 WBC 12. PLTS 136
N 70 E 2%
MCV 86

8. Case2
Over next 48 hrs his condition deteriorated .
He became oliguric and drowsy
Temp 37.2 to 37.4C
BP 90/60-100/60 mmHg
Became breathless and was put on O2 by facial mask
SO2 96%
Complete blood count Urine
•Proteins+
•Blood +++
•Nitrate-Neg
•RBC 2-5
•WBC 0-4
Clincal chemistry
•Total bilirubine 50 umol/L
• D.Bil 13
•Creat 200/500 umol/L Urea
19./22 CK 250/300
•Urate 450
•Na 137 K 4.8 VBG-PH 7.29
HCO3 17
Heptoglobin 0.1(0.3-2)
•ALT 85 U/L AST 100
•LDH 800/2000
Hb 85 WBC 13 N 80%
PLTS 60
Retics 3.6% MCV 86
PBF: fragmented RBC’s ++
Normal coagulation

9. Case2
Patient was shifted to ICCU
His platelet count was dropping and renal functions were deteriorating
Hemolysis was worsening
Special investigated were ordered
Complete blood count Urine
•Proteins++
•Blood +++
•Nitrate-Neg
•RBC 2-3
•WBC 0-2
Clincal chemistry
•Total bilirubine 60 umol/L
D.Bil 12
•Crea 550 umol/L Urea 25
Ca 2.3PO41.21
•Urate 515
•Na 137 K 4.6 VBG-HCO3
13
LDH 2500 U/L
Coombs test-Negative
Coagulation :INR 1.2 APTT 29
PT 13.7
: Hb 75 WBC 13.7 PLTS 28
Retics 4.6%
N 64 E 1.7%
MCV 86
PBF: fragmented RBC ++

10. Case2
A provisional diagnosis of HUS was made and pt was started on CVVHDF and plasmapheresis.
On clinical grounds STEC-HUS was high on cards but couldn’t be verified .
Secondary HUS due to history of bone marrow transplantation was another possibility or
Combined abnormalities of E.coli,bone marrow transplantation and complement mutation
Complete blood count Urine
•Proteins++
•Blood +++
•Nitrate-Neg
•RBC 2-3
•WBC 0-2
Clincal chemistry
•Blood C/S-No growth
•Stool C/S-no
E.coli,shigella,salmonella
•Shigatoxin-Not available
•ADAMTS 13-report awaited
•Low C3 Normal C4
•ANA-negative
•Antiphospholipid Ab-
Negative
•Hepatitis serlogy-Neg
Coagulation :INR 1 APTT 29 PT
13.7
: Hb 7 WBC 14.7 PLTS 25
MCV 86 Retics 4%
B12 and Folate levels-WNL

11. Progress
• After 3 sessions of CVVDHF his urine out put and kidney functions started
to improve,(sr creat 250/195)
• He received 10 sessions of plasmapheresis and Bil decresed to 15 and LDH
to 300,Platelets improved to 78.
• He was transferred to Mubarak Al Kabeer Hospital and has been
discharged last week with Platelet count of 110 and creat of 96 and Hb 10
.

12. Case328 yrs Kuwati woman with 24 weeks of pregnancy was admitted with complaints of headache .she had past
history of spontaneous abortion and hypothyroidism on thyroxine replacement.
She denied any history of Hypertension ,renal or hematological diseases.
Had not taken any medications in recent past.
On admission she was hypertensive (BP 160/100) and having pedal edema.,Temp 37.8C
No skin rash or neurodeficit.
She was started on antihypertensive medications--Methyldopa
Complete blood count Urine
•Proteins++
•Blood -nil
•Nitrate-Neg
•RBC 2-3
•WBC 0-2
Clincal chemistry
•Total bilirubine 20 umol/L
• D.Bil 5
•Crea 96 Urea 10 Ca 2.28
PO41.1
•Urate 350
•Na 137 K 4.5 VBG-WNL
•ALT 45
Coagulation :INR 1 APTT 29 PT
13.7
: Hb 10.4 WBC 12.7 PLTS 110
N 64
MCV 86

13. Case3
She was being treated as pre-eclampsia
She developed convulsions and was shifted to ICCU and given IV Magnesium sulphate
and Hydralazine.
In next 2 days she became oliguric ,icteric , anemic ,thrombocytopenic and developed
azotemia.
CTbrain-WNL
Complete blood count Urine
•Proteins++
•Blood ++
•Nitrate-Neg
•RBC 2-4
•WBC 0-2
Clincal chemistry
•Total bilirubine 50 umol/L
• D.Bil 11
•Crea 250 umol/L Urea 21 C
•Urate 550
•Na 136 K 4.7 VBG-WNL
•ALT87 U/L
•LDH 1200 U/L
•Heptoglobin 0.12
Coagulation :INR 1 APTT 29 PT
13.7
: Hb 8.5 WBC 9.8 PLTS 75
N 68% retics 3.7 %
MCV 88

14. Case3
There was clear cut evidence of MAHA---Thromboyctopenia,Hemolytic anemia and
AKI.
Her fundii were normal—No papilloedema
She had evidence of Neurological involvement—Headache and convulsions
So TTP was a very strong possibility.
Complete blood count Urine
•Proteins++
•Blood ++
•Nitrate-Neg
•RBC 2-4
•WBC 0-5
Clincal chemistry
•Total bilirubine100 umol/L
• D.Bil 26
•Crea 396 umol/L Urea 24.3
•Urate 515
•Na 137 K 4.8 VBG-WNL
• Heptoglobin 0.12
•ALT 100 U/L
•LDH 1600 U/L
•ANA/dSDNA-Neg C3/C4-N
•Anti phopholipid Ab-Neg
: Hb 7.8 WBC 14.7 PLTS 68
PBF: Fragmented RBC’s ++
B12/Folate levels-WNL
Coombs test-negative

15. Case3
So we decided to do Plasmapheresis with FFP as replacement
ADAMTS 13 activity and ADAMTS 133 Ab tests were sent to Kuwait university.
She was also given IV Methyl prednisolone pulses by hematologist.
Complete blood count Urine
•Proteins++
•Blood +++
•Nitrate-Neg
•RBC 2-5
•WBC 1-4
Clincal chemistry
•Total bilirubine 102 umol/L
• D.Bil 16
•Crea 328 umol/L Urea 15
Na 137 K 5 VBG-HCO3 17
LDH 1827 U/L
Heptoglobin 0.12
Blood and urine C/S-No
growth
HBSAG/HCVAb/HIV-
Negative
Coagulation :INR 1 APTT 30 PT
16
: Hb 7.8 WBC 10.4 PLTS 65
retics 5%

16. Case3
• She received 15 sessions of Plasma pheresis
• Had to be dialyzed twice during her hospital stay.
• ADAMTS 13 activity was <10 and ADMTS 13 Ab-not
detected.
• Her Hb improved to 11 gms ,T. Bil Came down to
18,Platelets improved to 136 and creat.to 90.
• Her proteinuria at one year is 0.5 gms /day,creat 92
and BP is controlled without any medications

17. Microangiopathic Hemolytic Anemia
• Microangiopathic hemolytic anemia is a term that is used to
describe the anemia that results from physical damage to the
red cells following the occlusion of arterioles and capillaries as
a result of fibrin deposition or platelet aggregation.
• Mechanical fragmentation occurs as the cells pass through the
fibrin meshwork of a microthrombus.
• Erythrocyte fragments with pointed extremities are called
schistocytes..
•

18. • HUS and TTP are characterized by the triad of:
• 1) microangiopathic anemia with red blood cell
fragmentation
• 2) thrombocytopenia and
• 3)AKI.
• TTP has the same three features plus the presence of:
• 4) fever and
• 5) neurological symptoms, creating a pentad.
• HUS and TTP share a histopathological phenotype called
thrombotic microangiopathy (TMA)

19. TMA classification

20. TMA
• The most frequently encountered TMAs clinically are: 1.HUS
associated with Shiga toxin–producing Escherichia coli
infection (STEC-HUS) and 2. thrombotic thrombocytopenic
purpura (TTP), followed by 3.atypical HUS (aHUS) and HUS
with a coexisting disease (called secondary HUS).

21. Other causes Of TMA
• TMAs are also part of the pathology of other conditions such
as:
• 1.Elevated hemolysis and liver enzymes and low platelet
count(collectively called HELLP syndrome.
• 2. Disseminated intravascular coagulation.
• 3. Malignant hypertension.
• 4 Antiphospholipid antibody syndrome.
• 5 .Scleroderma renal crisis.
• 6.Metalic valve prosthesis.

22. Initial, clinical diagnosis of HUS/TTP syndrome
(hospital day 1)
• Intravasal hemolysis with
fragmentocytes, Coombs-negative
– Laboratory signs: increased LDH,
decreased hemoglobin and
haptoglobin, free plasma
hemoglobin, increase of indirect
bilirubine
• Low platelet-count
– Exclusion of EDTA-induced decrease
of platelet number,
– Verified by investigation of blood-
smear
• Various presence of clinical signs:
– Neurological or renal
• No requirement of fever
• Simplified classification of HUS/TTP (1-2)
• Infection-related HUS
– EHEC D+HUS
– Pneumococcus P-HUS
– Influenza Neur-HUS
• Complement-related HUS
– Mutations aHUS, factor deficient
– Autoimmune anti-FH positive
• ADAMTS13 deficient TTP
– Autoimmune anti-ADAMTS13 pos
– Mutations Upshaw-Schulman sy
• Secondary forms, other rare entity
(1) Besbas et al, 2006, Kidney International
(2) Ariceta et al, 2009, Pediatric Nephrology

23. Initial, clinical diagnosis of HUS/TTP syndrome, i.e. thrombotic
microangiopathies
(hospital day 1)
• Intravasal hemolysis with fragmentocytes,
Coombs-negative
– Laboratory signs: increased LDH,
decreased hemoglobin and haptoglobin,
free plasma hemoglobin, increase of
indirect bilirubine
• Low platelet-count
– Exclusion of EDTA-induced decrease of
platelet number,
– Verified by investigation of blood-smear
• Various presence of clinical signs:
– Various neurological symptomps
– Acute renal failure
– Other
• No requirement of fever
• HUS: Hemolytic uremic syndrome
• TTP: Thrombotic thrombocytopenic
purpura
www.med-ed.virginia.edu/courses/path/innes/images/rcdjpegs/rcd
Slide thanks to Dr. Kline Bolton, UVA.

24. Complement pathways

25. Simplified schema of the complement system
Classical pathway (Immune complexes)
C3 activation
Alternative pathway (Spontaneous C3 activation)
Factor B and Factor D
Lectin pathway (Carbohydrate structures)
Alternative pathway
amplification
C3bBbP
C5 activation
C5-C9
Terminal Pathway
Opsonization
Antigen presentation
Antibody production
Anaphylatoxins C3a, C5a
Inflammation
Chemotaxis
Lysis
Cellular damages
Induction of apoptosis
Regulators:
MCP, DAF, Factor H and Factor I
Regulators:
C1-inhibitor, C4-binding protein, Factor I
Regulators:
CD59, S protein and Clusterin
•Cascade
•Activation: whole pathway
•Missing regulation: characteristic picture

26. Simplified schema of the complement system
Classical pathway (Immunecomplexes)
C3 activation
Alternative pathway (Spontaneous C3 activation)
Factor B and Factor D
Lectin pathway (Carbohydrate structures)
Alternative pathway
amplification
C3bBbP
C5 activation
C5-C9
Terminal Pathway
Opsonization
Antigen presentation
Antibody production
Anaphylatoxins C3a, C5a
Inflammation
Chemotaxis
Lysis
Cellular damages
Induction of apoptosis
Regulators:
MCP, DAF, Factor H and Factor I
Regulators:
C1-inhibitor, C4-binding protein, Factor I
Regulators:
CD59, S protein and Clusterin

27. DGK mutation

28. Pathogenesis of complement mediated atypical HUS
• Predisposition, rare genetic variants
– Mutations of complement alternative pathway regulators
(CFH>MCP>CFI>>THMB>CFB>C3>CFHR5>others)
• Predisposition, frequent genetic variants („complotype”)
– Haplotypes
• CFH H3/H8
• MCPggaac
– Copy-number variations
• CFHR1-3 deletion
• Predisposition, autoantibodies
– Development of anti-Factor H autoantibodies, based on genetic predisposition
(CFHR1 deletion)
• Direct disease-precipitating trigger
– Infections
– Pregnancy

29. STEC-HUS
• Shiga toxins are exotoxins produced by E. coli 0157:H7; O104:H4 ,and
also by other bacteria like Shigella dysenteriae 1 and Campylobacter jejuni
.
• They consist of two subunits: A and B . .
• The genes encoding Shiga toxin are found within lambdoid bacteriophages
present in all pathogenic STEC.
• B subunit of Shiga toxin binds to the glycosphingolipid receptor Gb3.
Cells lacking Gb3 expression are resistant to the toxic effects of Shiga
toxin. Glomeruli have high concentration of G3b.

30. STEC-HUS
• After binding to Gb3, Shiga toxin is endocytosed and transported to the
trans-Golgi network and then to to the endoplasmic reticulum (ER), finally
it translocate into host cell cytoplasm.
• . Shiga toxin acts in three main ways:
• 1. Inactivating ribosomes by removing an adenine residue from rRNA
causing Ribotoxic stress Response leading to activation of cytokines and
chemokines ( pro-inflammatory and pro-apoptotic pathways) .
• 2. Unfolded protein response triggered by Shiga toxin within the ER
induces apoptosis in cells.
• 3. Binding of the B subunit initiates a cytoplasmic transduction cascade (
distinct from the ribotoxic stress response) culminating in a pro-
thrombotic, pro-inflammatory cellular environment.

31. STEC-HUS

32. The cause of TTP are the pro-coagulant changes of in
microvessels
• ADAMTS13 metalloprotease cleaves von Willebrand Factor to small (4-6-8)
oligomers
• In case of ADaMTS13 deificency ultralarge vWF multimers remain
attached to the endothelial surface
• ADAMTS13 deficiency may be related to
– Mutation of ADAMTS13 (congenital form, ultrare, Upshaw-Schulman sy)
– Autoantibodies (acquired form, Moschcowitz sy, most frequent)
– Consumption

33. The cause of TTP are the pro-coagulant changes of in
microvessels
non-processed
ULVWF
processed oligomers
ADAMTS13

34. ULVWF
ADAMTS13
Y
Thrombocyte adhesion
Thrombocyte activation
Thrombocyte aggregation
Thrombocyte degranulation
Complement-
activation
Thrombus
Endothel-
activation
ADAMTS13 mutation ADAMTS13 inhibitory autoantibody
TTP

35. Acute disease episode,
hamolysis, thrombocytopenia
Clinical course of thrombotic microangiopathies (HUS/TTP syndrome)
aHUS
D+HUS
P-HUS
TTP
(Moschcowitz sy)
Congenital TTP
(Upshaw-Schulman sy)
Secondary
HUS/TTP
Shiga-like toxin
producing bacteria,
gastroenteritis
Complement deficiency
(Mutation, autoantibody)
Invasive pneumococcus
infection
DR11/DQ3 haplotype
Anti-ADAMTS13
Underlying disease, if treatable, good outcomes
ADAMTS13 mutation
?
Predisposition,
direct cause of disease
?
ESRD, dialysis, tx
Neurological defect
Neurological defect
Complication, outcome
Rarely

36. Initial, life-saving therapy
• PE with FFP is still the most effective treatment available for TTP .
– Rituximab (or cyclophosphamide) is indicated for patients with chronic
relapsing disease (autoimmune)
– Anti-platelet therapy and other immunosuppression may also be considered
• For HUS, most of the RCTs focused on typical HUS and showed that
supportive therapy including dialysis is still the most effective treatment.
Role of plasma exchange is doubtful.(1)
• The “Guideline for the investigation and initial therapy of diarrhea-
negative hemolytic uremic syndrome(aHUS)” recomends initiation of PE
with FFP in the first 24 hours (2)
– Eculizumab can be considered for proven cases of complement-mediated
aHUS
– Pulse cyclophosphamide and rituximab can be considered for anti-FH
autoantibody mediated aHUS
(1) Michael et al, The Cochrane Library 2009, Issue 1
(2) Ariceta et al, 2009, Ped Nephrol

37. Current Management Algorythm

38. Eculizimab

39. Eculizumab

40. Cost
• $6830 per 30 ml vial(300mgs)

41. SIDE EFFECTS
Serious Meningococcal Infections
• Life-threatening and fatal meningococcal infections have occurred in
patients treated with Soliris. The use of Soliris increases a patient's
susceptibility to serious meningococcal infections (septicemia and/or
meningitis).
• patients may have increased susceptibility to infections, especially with
encapsulated bacteria. Additionally, Aspergillus infections have occurred in
immunocompromised and neutropenic patients.
• Children treated with Soliris may be at increased risk of developing serious
infections due to Streptococcus pneumoniae and Haemophilus influenza
type b (Hib). Administer vaccinations for the prevention of Streptococcus
pneumoniae and Haemophilus influenza type b (Hib) infections according
to ACIP guidelines