Brain, heart, digestive tract symptoms common in aHUS: Study
Research into disease tends to focus solely on effects on kidneys
Disease manifestations that affect the brain, such as seizures, are relatively common with atypical hemolytic uremic syndrome (aHUS), as are digestive symptoms and heart-related problems, a study finds.
The study, “Extrarenal manifestations of atypical hemolytic uremic syndrome: a systematic review and meta-analysis,” was published in Pediatric Research.
aHUS is marked by inflammation and abnormal clotting in small blood vessels. The kidneys, which contain a large number of small blood vessels, are especially susceptible to aHUS-related damage, so research into the condition tends to focus on how the disease affects the kidneys. But aHUS also can cause damage to other parts of the body.
In the study, researchers reviewed of the existing scientific literature to ascertain what’s known about the extrarenal complications of aHUS.
“Despite growing research on aHUS reporting signs of extra-renal manifestations, we lack a comprehensive review of aHUS and extrarenal involvement drawn from the collectively published literature,” the researchers wrote. “This systematic review aims to characterize extrarenal involvement in aHUS, including its incidence and prevalence, as well as the related clinical outcomes.”
Extrarenal complications of aHUS
The review included data from 47 published studies covering 890 people with aHUS who ranged in age from 3 months to 66 years.
The most common site of extrarenal manifestations was the central nervous system, which includes the brain and spinal cord. Across all the studies, roughly 1 in 3 patients had central nervous system complications, the most common being seizures. Some studies reported these complications in as many as half the patients.
Gastrointestinal issues, such as vomiting and diarrhea, were also among the most frequently reported extrarenal manifestations and were documented in about a third of patients across all the studies.
Heart-related problems, such as cardiomyopathy, which is a disease of the heart muscle, weren’t as common, but weren’t rare, with about one in 10 patients having heart issues. It’s not clear if these heart problems arose due to aHUS or were complications of fluid overload and high blood pressure that can be caused by kidney disease. The results suggest heart health can be impacted in aHUS in either case.
aHUS is commonly associated with mutations in genes related to the complement cascade, a part of the immune system that becomes dysregulated in the disease. Some studies included in the review reported on these mutations, but others didn’t and the researchers weren’t able to firmly conclude about how different mutations might affect extrarenal manifestations of aHUS.
There also wasn’t reliable data on how these manifestations changed over time or responded to treatments. More research to evaluate how aHUS can affect the body beyond its impact on the kidneys is needed, the scientists said.
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