Episode 19: PPI’s and Hypomagnesemia
Author: Dr. Suneet Sood
Editor: Dr. Suneet Sood
Narrators: Thong Yi Kun, Alan Koay
What are you going to tell us today?
Let me tell you about an old man I saw yesterday. Interesting case, and taught me something.
This gentleman lives in an old age home. His children are abroad, but he is well looked-after, and fairly happy in this home.
Over the preceding few months, he had complained of increasing weakness and irritability, and was brought by the workers of the old age home to our general physician. This physician looked at him, and, in my opinion, took a somewhat cursory history. Anyway, examination showed nothing.
Yes, actually malnutrition is common in inmates of old age homes. In any case, our physician ran a battery of tests, and came up with slight hypocalcemia and hypokalemia, but severe hypomagnesaemia. The ECG changes were consistent with this electrolyte pattern.
How severe was the hypomagnesaemia?
Fairly severe. Zero-point-five millimoles per liter. Normal values are above zero-point-eight.
Well, we know that old age inmates can develop hypomagnesemia.
That’s true. And that’s what the physician thought: this is a very common setting for hypomagnesemia. In fact, oral treatment with magnesium lactate improved the patient, who felt much better after a few days of treatment.
The staff in these old age homes often does not care. Anyway, how did you get involved? You are a gastroenterologist.
That’s the point. The physician send sent the patient to me so that I could look at this patient for his chronic gastroesophageal reflux problem, perhaps scope him. When I took the history, I was a little surprised. The old age home which the patient attends is part of a chain with an excellent reputation. In fact, one of my relatives lives in one of these. I’ve visited him, and I thought the staff was actually very good.
So I asked around, and, sure enough, the patient was actually well cared for in this home. The inmates here do not get malnourished.
Well, this patient surely did. Otherwise how do you explain his severe hypomagnesemia?
That’s what I’m coming to. I realized that this patient has been on omeprazole for a long time. Proton pump inhibitors are among the important causes of hypomagnesemia.
Yes. The other important cause of hypomagnesemia is diuretic therapy. In addition, several other drugs have been implicated.
How do PPIs cause hypomagnesemia?
It seems that they interfere with absorption of magnesium.
Is this hypomagnesemia dose-related?
Maybe, but there’s some recent evidence that it’s not, so I think that it causes low Mg levels in susceptible persons only.
So you stopped the omeprazole?
Well, I can’t. He needs the PPI for his reflux. My options are to try to control the Mg levels with supplements. If this does not work, I’ll have to send him to a surgeon for anti-reflux therapy.
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