Gut inflammation triggers rare case of aHUS in woman, 38
Challenging diagnosis because patient did not have traditional disease markers
A 38-year-old woman in Portugal developed atypical hemolytic uremic syndrome (aHUS) despite showing no typical markers of the disease after she experienced gastrointestinal inflammation, according to a case report.
“This case highlights the diagnostic and management challenges in aHUS when traditional disease markers are absent and emphasizes the importance of tailored therapeutic approaches,” researchers wrote.
The report, “Beyond the Norm: Gastroenteritis-Induced Atypical Hemolytic Uremic Syndrome in the Absence of Complement Dysfunction,” was published in Cureus.
aHUS is characterized by the formation of blood clots inside small blood vessels, or thrombotic microangiopathy (TMA). It is mainly caused by an overactivation of the complement cascade, a group of immune proteins that help fight off infections. However, some patients develop the disease without a clear involvement of the complement cascade.
aHUS developed even though patient had normal complement levels
In the report, researchers in Portugal described the case of a 38-year-old woman who developed aHUS following an episode of gastroenteritis, or inflammation of the digestive tract, even though she had normal complement levels.
The woman was admitted to the emergency department with severe abdominal pain, nausea, vomiting, and diarrhea that had been lasting for one week. Her symptoms were consistent with gastroenteritis, but she progressively developed fatigue, shortness of breath, and dark-colored urine.
At admission, she was pale, and had mild jaundice (yellowing of the skin and eyes) and swelling in her lower extremities. She also had slightly low blood pressure, an elevated heart rate, and a normal breathing rate.
Initial laboratory tests indicated she had high levels of C-reactive protein, which is an inflammation marker, thrombocytopenia (low platelet counts), and mild elevation in liver enzyme levels. She also had a marked elevation of lactate dehydrogenase, consistent with hemolytic anemia, which is a type of anemia driven by red blood cells being destroyed faster than they can be made.
She also showed signs of acute kidney failure that required hemodialysis, a type of treatment used to filter waste and water from the blood when the kidneys are no longer working properly. A kidney biopsy revealed classic signs of TMA.
Even though she had many typical features of aHUS, the levels and function of complement components were within the normal range. Further analysis excluded other possible causes for her symptoms, including aHUS that’s caused by bacterial infections and immune-mediated hemolytic anemia.
Diagnosis of aHUS with no apparent underlying secondary cause
The combination of normal complement activity, no evidence of infections or autoimmune conditions, and kidney biopsy findings led to a diagnosis of aHUS with no apparent underlying secondary cause.
“This suggests that in some instances, aHUS may be triggered by factors other than complement dysregulation, possibly related to the preceding gastroenteritis,” the researchers wrote.
The patient was managed conservatively with supportive care, including intravenous (into-the-vein) infusion of fluids and dialysis. After several weeks, her kidney function progressively improved and dialysis was discontinued. At follow-up, she remained in stable condition, with no recurrence of hemolysis (red blood destruction) or thrombocytopenia.
“In cases where complement dysregulation is absent, conservative management with supportive care may lead to favorable outcomes,” the researchers wrote. “This case contributes to the growing understanding of aHUS as a heterogeneous disease and suggests that complement-independent mechanisms may play a role in some cases, necessitating ongoing research into alternative therapeutic strategies.”
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