Adult Hemolytic Uremic Syndrome as a Diagnostic Challenge

Area of Science:

• Nephrology
• Hematology
• Internal Medicine

Background:

• Hemolytic uremic syndrome (HUS) is a severe condition characterized by microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and acute kidney injury (AKI).
• Adult-onset HUS is underrecognized, particularly in resource-limited settings, often presenting with atypical features.
• Shiga toxin-producing Escherichia coli (STEC) is a common cause in children, but other etiologies exist in adults.

Observation:

• A 35-year-old male presented with fever, bloody diarrhea, jaundice, and dark urine, exhibiting MAHA, thrombocytopenia, and AKI.
• Elevated direct bilirubin suggested hepatic involvement; blood cultures revealed Escherichia coli, though stool cultures were negative.
• Severe vitamin B12 deficiency raised suspicion for pseudo-thrombotic microangiopathy (pseudo-TMA), managed concurrently.

Findings:

• The patient was diagnosed with typical HUS based on clinical presentation and peripheral smear findings, despite unavailable ADAMTS13 and complement assays.
• Treatment included corticosteroids and supportive care for non-cardiogenic pulmonary edema, alongside hematinics for B12 deficiency.
• Full renal recovery and improvement in hemoglobin were observed at two-month follow-up.

Implications:

• This case underscores the diagnostic and therapeutic challenges of adult HUS, especially with overlapping pseudo-TMA and potential infectious triggers.
• Limited access to confirmatory tests like ADAMTS13 necessitates reliance on clinical evaluation and exclusion of mimickers.
• Increased awareness and systematic evaluation are crucial for managing adult HUS, particularly in regions like India.