Kyle Wood, MD, comments on the presenting signs and symptoms of enteric hyperoxaluria and complications of untreated disease.
Kristie Kahl: What are the symptoms of enteric hyperoxaluria?
Kyle Wood, MD: High oxalate levels in the urine may not have symptoms. Just because they have hyperoxaluria does not mean that they’ll have symptoms because of the high oxalate. However, with high oxalate comes the increased risk of forming kidney stones, so some of the presenting symptoms for enteric hyperoxaluria may be kidney stone related or kidney stone event related. In addition, the symptoms that the patients may experience that lead to thinking about enteric hyperoxaluria may have to do with the malabsorptive process. They may present, say after a bariatric surgery, with signs of malabsorption—increased bowel movements, diarrhea—and those may lead you to believe that they have a malabsorptive process in their gut that could be explaining their enteric hyperoxaluria. A lot of the symptoms are unrelated to the actual levels of oxalate but have to do with the consequences, or sequela, of having high oxalate. Kidney stone events and chronic kidney disease may result. In severe cases, you can have oxalate deposition in other tissues. That could be a manifestation as well.
Kristie Kahl: You mentioned the malabsorption. How can that lead to enteric hyperoxaluria? What are some of the diseases that cause malabsorption absorption?
Kyle Wood, MD: That’s a great question. Pathophysiologically, let’s say you have bariatric surgery and you have a malabsorptive process that’s created to help with weight loss. But in the process of that, you can have fat malabsorption and bile acid malabsorption. What happens is the bile acids and the fats saponify, or bind, to the calcium in the gut. In that process, the calcium can no longer bind to the oxalate, so the gut oxalate is free to be absorbed through the gut, into the bloodstream. That higher level of oxalate that gets absorbed into the bloodstream gets excreted in the kidneys, causing high oxalate in the urine. That’s the main pathophysiological process. The other thought is in these malabsorptive states. You may have increased gut permeability, which allows for more oxalate to be absorbed as well. We have mentioned some diseases that cause this. Any bariatric surgery will purposely create a malabsorptive state. Gastric bypass—Roux-en-Y gastric bypass—a duodenal switch, or biliopancreatic diversion, can all cause malabsorption processes. Some disease states, like inflammatory bowel diseases—like Crohn disease—can cause a malabsorptive process that can cause enteric hyperoxaluria. Cystic fibrosis, has issues with pancreatic enzymes, thus the malabsorptive process can present with enteric hyperoxaluria as well. Anytime you’re looking at the bowels or anything that’s causing a malabsorptive state, or if there’s been surgical removal of the small intestine, these conditions can lead to the same process. You could have enteric hyperoxaluria.
Transcript edited for clarity.