Summary about Disease
Microangiopathic Hemolytic Anemia (MAHA) is a type of hemolytic anemia characterized by damage to red blood cells as they pass through abnormally narrowed or obstructed microvasculature (small blood vessels). This damage leads to fragmentation of the red blood cells (schistocytes) and premature destruction (hemolysis). MAHA is not a disease itself, but rather a finding associated with several underlying conditions.
Symptoms
Symptoms vary depending on the underlying cause and the severity of the anemia. Common symptoms include:
Fatigue
Weakness
Pale skin (pallor)
Jaundice (yellowing of the skin and eyes)
Dark urine
Shortness of breath
Rapid heart rate
Easy bruising or bleeding
Neurological symptoms (confusion, seizures, stroke-like symptoms) can occur in some MAHA subtypes.
Causes
MAHA is caused by conditions that damage small blood vessels, leading to red blood cell fragmentation. Common causes include:
Thrombotic Thrombocytopenic Purpura (TTP): Deficiency of ADAMTS13 enzyme.
Hemolytic Uremic Syndrome (HUS): Often caused by Shiga toxin-producing E. coli (STEC-HUS). Atypical HUS (aHUS) has genetic or complement dysregulation causes.
Disseminated Intravascular Coagulation (DIC): Widespread clotting and bleeding due to an underlying condition.
HELLP Syndrome: A complication of pregnancy (Hemolysis, Elevated Liver enzymes, Low Platelet count).
Malignant Hypertension: Severely elevated blood pressure.
Systemic Lupus Erythematosus (SLE) and other autoimmune disorders: Can cause vasculitis that damages small vessels.
Cancer: Some cancers can cause MAHA.
Certain Medications: Some drugs can induce MAHA.
Scleroderma renal crisis
Medicine Used
Treatment depends entirely on the underlying cause of the MAHA. Some examples include:
TTP: Plasma exchange (PEX) to replace ADAMTS13. Caplacizumab (anti-vWF antibody) is also used.
HUS (STEC-HUS): Supportive care (fluids, blood transfusions, dialysis if needed). Antibiotics are generally avoided.
aHUS: Eculizumab (complement inhibitor) or other complement inhibitors.
DIC: Treatment of the underlying cause is paramount. Blood products (platelets, clotting factors) may be needed.
HELLP Syndrome: Delivery of the baby is the primary treatment. Magnesium sulfate for seizure prophylaxis.
Malignant Hypertension: Aggressive blood pressure control.
Autoimmune disorders: Immunosuppressants (corticosteroids, etc.).
Transfusions: May be needed to treat anemia.
Is Communicable
MAHA itself is not communicable. However, some of the underlying causes, such as STEC-HUS, can be infectious (spread through contaminated food).
Precautions
Precautions depend on the underlying cause. For STEC-HUS, proper food handling and hygiene are crucial to prevent infection. In general, preventing MAHA involves managing the underlying conditions that can lead to it (e.g., controlling blood pressure, managing autoimmune diseases, avoiding certain medications).
How long does an outbreak last?
The duration of an outbreak depends on the underlying cause.
STEC-HUS outbreaks: Can last weeks to months, depending on the source of contamination and public health interventions.
TTP: Can be acute and life-threatening if not treated promptly, with ongoing management required.
HELLP Syndrome: Resolves after delivery of the baby.
Other causes: Outbreak length depends on the success of treatment for the underlying condition.
How is it diagnosed?
Diagnosis involves:
Blood Smear: Examination of a blood sample under a microscope to look for schistocytes (fragmented red blood cells).
Complete Blood Count (CBC): To assess for anemia (low hemoglobin and hematocrit) and thrombocytopenia (low platelet count).
Lactate Dehydrogenase (LDH): Elevated LDH indicates red blood cell destruction.
Haptoglobin: Low haptoglobin indicates red blood cell destruction.
Bilirubin: Elevated indirect bilirubin indicates red blood cell destruction.
Coombs Test (Direct Antiglobulin Test): Usually negative in MAHA (differentiates from autoimmune hemolytic anemia).
ADAMTS13 Testing: To diagnose TTP.
Stool Testing: To detect Shiga toxin in suspected STEC-HUS cases.
Complement Testing: To evaluate for aHUS.
Kidney function tests (BUN, creatinine): assess kidney damage
Liver Function Tests: To assess liver damage.
Evaluation for underlying conditions: Investigation to identify the underlying cause of MAHA.
Timeline of Symptoms
The timeline of symptoms varies greatly depending on the underlying cause and severity.
TTP and HUS: Can develop rapidly, over days to weeks.
HELLP Syndrome: Typically occurs in the late stages of pregnancy.
DIC: Can develop acutely in response to a triggering event.
Other causes: Onset may be gradual or sudden, depending on the underlying condition. Neurological symptoms can appear at any time, often indicating a more severe form of MAHA.
Important Considerations
MAHA is not a diagnosis in itself; identifying the underlying cause is crucial for appropriate treatment.
MAHA can be life-threatening, requiring prompt diagnosis and treatment.
Neurological symptoms in MAHA are a serious sign and require immediate medical attention.
Treatment strategies are highly variable and depend on the specific underlying cause.
Some causes of MAHA, such as aHUS, require specialized testing and treatment.
Pregnant women with symptoms suggestive of HELLP syndrome should be evaluated immediately.