The Heparin – Potassium Connection

Ever since I read about the Six Degrees of Kevin Bacon, I enjoy identifying incredulous sounding chain of medical events. I had an unfortunate patient with a newly started CPAP mask that gave him a middle ear infection (actually a rare complication of CPAP), which in turn led to trials of 3-4 antibiotic courses that precipitated C.Diff colitis with profuse diarrhea causing dehydration resulting in acute kidney injury with hyperkalemia! So CPAP caused Hyperkalemia ?! Just wow ! 😅😲

How about Heparin causing Hyperkalemia? May sound incredulous for those who don’t know. It isn’t that uncommon yet not so well known. For a while now (as early as 1950s/1960s ) Heparin has been known to cause suppression of Aldosterone by inhibiting production in Zona Glomerulosa, resulting in potassium retention. Though not significant enough in most people, potassium retention is more likely in elderly people or those with CKD, diabetes, or on ACE inhibitors. Pubmed has many case reports ! 1985, 2002, 2008, 2014, 2022 for a few.

BUT – this should remain a diagnosis of exclusion, rule out other causes first. The best way to prove it, of course, would be to stop heparin, see potassium level go down & then go back up on restarting Heparin. A 2022 case report table actually tabulated the potassium levels with heparin start, stop & restart. Don’t really have to prove this in your patient – Instead, just switch to an alternative such as Fondaparinux. Don’t forget to enlist hyperkalemia as a possible adverse effect of Heparin on your patient’s EMR account for future reference.

💡 Some practical clinical tips about the Heparin-Potassium connection 🔎:

– Takes 3-4 days for potassium to go up after starting Heparin
– K+ Level goes up to 5.5 to 6.5 range, if higher, something else may be at play but Heparin could contribute
– Can happen with both IV & Subcutaneous (SQ) heparin.
– If Heparin-induced Aldosterone suppression can retain potassium, it can also deplete sodium!
– Heparin like drugs such as a Enoxaparin can cause the same effect, so switch to Fondaparinux instead!

P.S. Say the word Fondaparinux in front of a mirror to get the full effect of how fancy you sound 😎