IN THE NEWS- HYPOMAGNESEMIA AND PPI?

Two recent papers in AJKD describe two independent observations of proton pump inhibitor induced hypomagnesemia. We have seen a lot of AIN from PPI as a class of drugs and perhaps the most common cause of AIN now.  But their association with low mg levels is new.
The first paper in AJKD describes 4 cases of long term PPI induced hypomagnesemia, hypokalemia, hypocalcemia and all were on different PPI, so a class effect.
Although only four cases, they couldn't say for sure if it is dose related or time related but seems more like a long term being on PPI effect. The low K and Ca might be a low Mg related effect. Low K from the ROMK effect and low Ca from an PTH related effect of low Mg.
The mechanism of why PPIs cause low Mg is not described in detail but thought about. One reason could be decreased colon transport of Mg which is mediated via the TRPM channels.  Its possible that the PH changes from PPI alter the TRPMs. Fe Mg was low in all cases 0.8-1% suggesting the kidney is doing the right thing.
Prior case reports and the second paper clearly show that its more of a GI loss of Mg due to a Ph effect rather than a mg wasting syndrome seen with perhaps CNI and post transplant patients.

Check it out
http://www.ncbi.nlm.nih.gov/pubmed/20493607
http://www.ncbi.nlm.nih.gov/pubmed/20189276
http://www.ncbi.nlm.nih.gov/pubmed/19920278