Brain & Kidney: The CerebroRenal Syndrome

Why do we need a new syndrome? Aren’t 5 types of cardiorenal syndrome enough?

Well, if we can have gastrorenal syndrome (which is sometimes claimed to be not real), it is very hard to argue that there should be no cerebro-renal syndrome. The brain is surely more important than the gut?

And look at the consequences of creating a new syndrome: it would have it’s own wikipedia page, a MeSH term. Even it’s very own society, a journal, a conference and even a textbook.

So, here we present, the different types of the cerebrorenal syndromes:

Type 1 Cerebrorenal Syndrome: aka Acute cerebrorenal syndrome. Acute kidney injury (AKI) in patients with cerebral disease: higher risk in dementia — think pre-renal, polypharmacy — though cause and effect is sometimes unclear. More research is needed.

Type 2 Cerebrorenal Syndrome: aka Chronic cerebrorenal syndrome. Chronic kidney disease (CKD) in patients with cerebrovascular disease.

Type 3 Cerebrorenal Syndrome: The brain causes electrolyte disorders. Think about it. Mind blowing, isn’t it? Hyponatremia can be from SIADH — or if you believe in it, something actually called cerebral salt wasting. Lithium causing diabetes insipidus is the psycho-cerebrorenal variant. Read all about it in the #NephMadness coverage.

“The kidney is usually smart about salt and water, but gets dumber when there is a tumor in the brain..” — Mark Reid #1106

Type 4 Cerebrorenal Syndrome: More aptly termed Dialysis-Cerebral syndromes.

Four subtypes:

4a: Dialysis dysequilibrium (not seen often now — but can always happen if one is not careful ordering dialysis in chronically uremic patients);

4b: Dialysis induced dementia: mostly from aluminium in dialysate. Not seen any more with modern water treatment, specifically reverse osmosis

4c: Dialysis induced ischemic changes in the white matter, when examined by diffusion tensor magnetic resonance imaging (eg as described here)

4d: Polypharmacy variant. When dialysis patients are given drugs they should not be given. Like baclofen

Type 5 Cerebrorenal Syndrome: Type 5 not because it’s not important, but because we are still scratching at the surface. The brian-kidney axis. There is crosstalk between the two. It involves the renin-angiotensin system. Lots of papers and research to come. We might even figure out how this can be clinically meaningful one day.

PS: If it’s not clear so far, the whole post above is #FakeNews. Just like Joel with his gastrorenal syndrome, one can have fun with two other organs and making a portmanteau syndrome.