Peptic ulcers - hyperparathyroidism

[Phloston]

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What is the mechanism behind peptic ulcer formation secondary to hyperparathyroidism?

This has nothing to do with MEN-I (Wermer syndrome) btw. Kaplan QBank says increased PTH can lead to peptic ulcers, and they don't give a mechanism/explanation. They even have a vignette of a guy with an ulcer and hypercalcaemia, and I thought it was MEN-I, but it wasn't; they also went on to say that ZES tends to produce multiple, not isolated, ulcers.

The only thing I can think of is increased PTH --> hypercalcaemia --> pancreatitis --> islet delta-cell damage --> decreased somatostatin --> increased HCl secretion --> ulcers.

That actually sounds like a stretch to me, but the only reason I feel that mechanism is a possibility is because if DM can occur secondary to pancreatitis, and beta-cells are more numerous than delta-cells, then delta-cell numbers could definitely decline as well.

A more simple explanation is that it could just be due to decreased effectiveness of pancreatic bicarbonate secretion.

Any thoughts?

 

[thehundredthone]

HyperPTH -> Hyper Ca -> increased gastrin -> increased HCl -> peptic ulcer? Edit: Found an old thread: http://forums.studentdoctor.net/archive/index.php/t-397945.html And the diagram they're referring to: http://cal.vet.upenn.edu/projects/saortho/chapter_59/59F23.jpg

 

[Phloston]

That's so odd. I've never heard of Ca2+ stimulating gastrin secretion before.

What would be the mechanism for that?

 

[Phloston]

I think I just figured it out.

That diagram shows "high Ca2+ in diet." So I'd think Ca2+ + H2O --> Ca(OH)2 , which would increase gastric pH, thereby increasing gastrin secretion.

 

[thehundredthone]

Well actually there is a Ca receptor called CaR.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2716662/

https://circle.ubc.ca/handle/2429/4720

 

[Phloston]

Thanks so much for posting that.

I had thought the CaR was just on the parathyroid gland.

However now that I think of it, I have encountered a practice question that had mentioned an "experiment in an animal with enterocytic CaR being knocked out..." It had something to do with vitamin D, but I hadn't realized gastrin was tied into that.

 

[Suncrusher]

ugh i hope i dont get any questions like this one on the real deal. this has gotta be one of the smallest pieces of minutiae I've ever seen on this subforum. I know it's from kaplan, but still...

 

[thehundredthone]

I really doubt the pathophysiology of the development of peptic ulcers in hypercalcaemia will be asked on the exam, I think Phloston just wanted to understand why. However, the association between hypercalcaemia and peptic ulcers is one to keep in mind. Bones, stones, abdominal groans (and psychic overtones) or whatever version of it you might have heard.