COVID-19 triggers aHUS in man following kidney transplant
Study: Treatment with Ultomiris helped resolve his symptoms
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A COVID-19 infection apparently triggered the development of atypical hemolytic uremic syndrome (aHUS) in a 75-year-old man who had recently received a kidney transplant, according to a case report.
Treatment with Ultomiris (ravulizumab) helped resolve his symptoms, supporting the use of the medication post-kidney transplant. Some kidney transplant recipients are particularly susceptible to aHUS and other types of thrombotic microangiopathy (TMA), a group of diseases that causes blood clots to form in small blood vessels. However, doctors may not consider aHUS when diagnosing TMA in these individuals, who are often older than most people who begin showing signs of the condition.
“This case underscores the importance of considering [aHUS] in the differential diagnosis of posttransplant TMA … demonstrating that age alone should not preclude diagnostic consideration, and supports [Ultomiris] as an effective therapeutic option in this setting,” researchers wrote.
The study, “Case Report: COVID-19 unmasks factor H mutation-driven hemolytic uremic syndrome in a previously undiagnosed septuagenarian kidney transplant recipient,” was published in Frontiers in Medicine.
Genetic mutations are often at the root of aHUS
Abnormal activity in the complement cascade, a part of the immune system, causes blood clotting and organ damage in aHUS. The kidneys often experience the most damage, and aHUS can lead to kidney failure.
Genetic mutations are often at the root of aHUS, but they are not sufficient to trigger the condition in isolation. Viral infection, kidney transplants, or other events may cause symptoms to develop in someone with a genetic predisposition to aHUS.
There are two approved medications for aHUS, including Ultomiris. Both target the complement system to decrease the risk of blood clots. However, “experience [with Ultomiris] in the post-transplant setting remains limited, with data currently restricted to a small cohort of eight kidney transplant recipients,” the research team wrote.
Man initially recovered well from the transplant
In the present study, the researchers described a 75-year-old man with aHUS. His symptoms developed after a kidney transplant and subsequent COVID-19 infection, and he responded well to Ultomiris.
Doctors believed his kidney disease was related to his history of high blood pressure. Otherwise, the man was healthy. His sister had also received a kidney transplant previously.
He initially recovered well from the transplant. However, the man came into the clinic three months later, showing signs of abnormal kidney function, which improved with treatment.
In October 2024, the patient developed a mild COVID-19 infection. After this, he again showed signs of potential kidney problems. Lab tests showed he had elevated creatinine, a waste product, in his blood and high levels of proteins in his urine, which could suggest the kidney wasn’t functioning properly. He also experienced swelling in his limbs and had high blood pressure.
Follow-up testing revealed TMA and dysregulation in the complement cascade. Genetic testing also showed a mutation that can cause aHUS.
“In retrospect, we suspect this mutation likely underpinned the kidney disease in both the patient and his sister, who was not available for genetic testing,” the researchers wrote.
After two doses of Ultomiris, delivered two weeks apart, the man’s kidney function improved.
Such diagnoses may obscure an underlying, undetected disease with the potential to recur after transplantation.
The man’s case includes several unusual features not commonly seen in aHUS. His advanced age was one notable facet, as most people with aHUS develop symptoms earlier in life. COVID-19 infection as a possible triggering event, along with the slow, subtle progression of symptoms, also stood out.
These elements emphasize that clinicians should consider aHUS as a possible diagnosis even when its features don’t follow normal patterns, according to the research team. Additionally, they noted that the inconclusive initial kidney disease diagnosis that led to the transplant could have prevented earlier recognition of aHUS.
“Such diagnoses may obscure an underlying, undetected disease with the potential to recur after transplantation,” they wrote.
The case adds to the evidence that Ultomiris may be an effective treatment for aHUS that develops after a kidney transplant.
