S18C232 - Acquired hemolytic anemia Flashcards
Tests for hemolysis
- hb and Hct decreased
- reticulocyte increased
- peripheral smear - schistocytes from shearing force, spherocytes from extravascular hemolysis
- LDH - elevated
- K may be elevated
- haptoglobin decreased - sign of intravascular hemolysis
- bilirubin increased
Immune-mediated acquired hemolytic anemia
AUTOIMMUNE
- will have positive DAT
- AIHA ore common in women, assoc with lymphoproliferative, autoimmune or infxs dz
ALLOIMMUNE
- requires exposure to allogeneic RBC and subsequent alloantibody formation, do not react with pts own RBC
- eg. Rh- mom and Rh + baby
- usually requires a prior TFn exposure
DRUG-INDUCED Hemolytic anemia
- tx: steroids
- TFN will aggravate the hemolysis
- catchein, cefotetan, CTX, cephalothin, diclofenac, interferon, levodopa, mefenamic acid, methyldopa, oxaliplatin, Pen G, quinidine, rifampin
DDx for DAT positive
- AIHA
- hemolytic tfn rxn
- hemolytic dz of newborn
- tranplant
- druge-related
- IVIG
- Rh immunoglobulin therapy
- SCD
- beta-thal
- mulitple myeloma
- hodgkin
- SLE
- HIV
Microangiopathic syndromes
-microangiopathic hemolytic anemia
-TTP and HUS
-involve platelet aggregation in microvasculature via mediation ofr vWF
-RBC are fragmented during travel through partially occluded arterioles/capillaries
-TTP more common in adults and more prominent neurologic effects
HUS more commin in kids and more specific to renal system
TTP
-thrombotic thrombocytopenic purpura
-pentad:
1 CNS abnormalities
2 renal pathology
3 fever
4 microangiopathic hemolytic anemia
5 thrombocytopenia
-dx: hemolytic anemia + thrombocytopenia with no other cause
-high mortality rate unless given PlEx
-ddx: malignant HTN, sepsis, SLE, HELLP
TTP: pathophys
- vWF multimers accumulate due to decreased ADAMTS-13 acitivty, causes platelet aggregation and RBCs are sheared across the microthrombi
- thrombocytopenia
TTP: sx
- neuro deficits
- coma
- AKI
- ARF
TTP vs DIC vs HELLP
- TTP has normal coag studies b/c TTP thrombi don’t use up fibrin
- HELLP should respond to steroids w/in 24h by an increase in platelets whereas TTP will not, delivery also will not improve TTP
- if TTP treated with PlEx then pregnancy can be carried to term
TTP: Tx
- daily plasmapheresis (plasma exchange) until platelets normal
- avoid platelet TFN except for life-threatening bleed
HUS
- microangiopathic hemolytic anemia, acute neprhopathy/fenal failure, thrombocytopenia
- typical: occurs 1w into infxs bloody diarrhea episode with fever (O157:H7), shiga-toxin present (but also shigella, yersinia, c jej, salmonella)
- atypical: difficult to distinguish from TTP, occurs in older children and adults caused by strep or EBV or non-infxs source such as bone marrow transplant
HUS: pathophys
- toxin absorbed into circulation, affinity for glomerular and renal rubules, microvascular injury causes platelet aggregation, thrombi, microangiopathic hemolytic anemia, ischemia, necrosis
- may also affect pancreatic beta cells leading to hyperglycemia
- onset of HUS is 2-14d after diarrhea develops
HUS: Tx
- supportive, fluids for renal failure, analgesia,
- NO immodium
- NO Abx - may increase shiga toxin expression and increased risk of HUS
Macrovascular hemolysis
- prosthetic heart valves
- aortofem bypass
- Ao valve dz
- coarctation
- VAD
- Dx: scheistocytes on smear
- if mild give iron and folate, BB may help
Malaria
- world’s most common cause of hemolytic anemia
- plasmodium lyses RBCs
Other infxs causes of hemolysis:
- babesia microti/divergens (Babesiosis) from tick bites or blood tfn
- clostridium perfringens (gas gangrene) and direct lysis of RBC via toxins
- leptospirosis - ingestion of contaminted water/food (weil’s syndrome)
