Urodilatin

Where it comes from

Made in

Distal tubule cells of the kidney, secreted into the urine, not the blood

Sent out by

Salt and volume loading

Acts on

• Collecting duct (sodium reabsorption)
• Kidney vessels

What it does

• Makes the kidney shed sodium and water from the lumen side ²
• Resists the enzymes that destroy ANP in the tubule
• Not found in blood in health, which is why it is called a paracrine peptide of the kidney ²

In medicine

• Ularitide, synthetic urodilatin, was infused in 2,157 patients with acute heart failure: it lowered filling pressures and NT-proBNP but left cardiovascular death unchanged ¹
• No urodilatin preparation is approved in any country, and the ularitide programme stopped after that trial ¹
• It is not part of any routine blood panel; the assays are research tools, and urine rather than blood is the sample that makes sense ²

Beyond the body’s own use

• Urinary urodilatin is used in research as a read-out of how the kidney is handling salt, rising with a salt load and falling with restriction; it is not a clinical test ²
• The ularitide result is a large part of why the natriuretic peptide family is now pursued by blocking breakdown rather than by infusion ¹
• Nothing is in trials and nothing is claimed for it outside research: it survives minutes in blood, and nothing swallowed reaches the tubule where it acts