Hyperkalemia gets so much attention because it's a common, complex emergency with potentially life-threatening cardiac implications.
Here's my approach to working up and managing HyperK in the hospital, along with some key pathophys everyone should know!
- Thread -
Check out these @pointofcaremed digital resources on hyperkalemia for use at the point of care!
Online Template
pointofcaremedicine.com/inpatient/hyperkalemia
Podcast
podcasters.spotify.com/pod/show/pointofcarepodcast
YouTube
youtu.be/8CW4ryTJshs?si=wUkDoOy8rNoOwd1o
Though cutoffs vary, HyperK is generally considered to be a K > 5.5 mEq/L
Symptoms usually aren't present until K > 7.0 mEq/L or if the level rises rapidly due to an acute insult.
HyperK is present in ~2-3% of the population, but up to 50% in those with CKD!
Why do we take HyperK so seriously?
Potassium influences resting membrane potential, and HyperK can lead to increased excitability of cells.
The most dangerous consequence of this includes cardiac arrythmias (look out for a future thread on this)!
At baseline, resting membrane potentials are NEGATIVE but vary by cell type (neuron, muscle, cardiac, etc.) based on ion channels and ion pump activity.
At baseline, only 2% of total body K is extracellular, and this level is tightly regulated.
As such, there is more K INSIDE cells.
HyperK leads to more K OUTSIDE cells.
This makes the potential LESS NEGATIVE.
In other words, the potential becomes closer to zero (i.e -90 --> -80).
These changes lead to downstream issues with electrical conduction.
Hyperkalemia from acute insults is usually short-lived unless there is an ongoing or chronic process.
Common examples of these processes include:
- Renal disease
- Acidosis
- Hypoaldosteronism
Here's a checklist to use when admitting a patient with hyperkalemia.
STAT EKG - calcium gluconate if any changes
Gut Check - repeat (VBG okay for ballpark) to rule out pseudohyperkalemia
Triage for HyperK Emergency
Chart Check - known ESRD/dialysis
HyperK Emergency is present if one or more of:
1. K > 6.5 mEq/L
2. Clinical changes, including (not limited to): EKG changes, muscle weakness, paresthesias
3. An active process that may lead to persistently elevated K levels (ESRD, GI Bleed, rhabdo, TLS)
Here is the most pertinent info to collect for your HPI.
Common symptoms are all the result of changes in membrane potential.
If the patient has ESRD, it is important to know if they make urine. This will help determine which temporizing treatments may be efficacious.
Etiology/Differential Buckets
- Reduced Elimination (most common)
- Shifting into Extraceullar Space
- Extracellular Release
- Excess Intake from Diet
Acidosis can lead to HyperK
Why?
Acidosis messes with the efficacy of the Na+/H+ antiporter.
This leads to decreased intracellular Na+.
This gradient change impacts the efficacy of the Na/K-ATPase pump, which in turn leads to increased extracellular K.
Common meds that can cause hyperkalemia:
- ACE/ARBs
- MRAs
- NSAIDs
- TMP-SMX
All of these act by decreasing the effect of aldosterone.
Aldosterone primarily acts on distal tubules and leads to Na reabsorption and K secretion.
Other medications can redistribute K
Treatment of HyperK
Stabilize:
- If EKG changes or emergency
- Calcium gluconate 1-2g q5 minutes until EKG normalizes. Only lasts 30-60 minutes.
Temporize:
- If emergency - NOT everyone
- Insulin 10 U (add dextrose if BG <250).
- Albuterol is only an add-on
Eliminate:
- If emergency OR concern the K will continue to rise
- If patient can urinate, give furosemide 40mg IV in naive patients.
- Give sodium zirconium cyclosilicate (Lokelma) 10mg TID if patient can make stool. Give with a laxative (can lead to constipation).
For monitoring in an emergency, once EKG changes have resolved:
- Trend EKG and K q2-4 hours
- Continuous telemetry
Remember that calcium gluconate only lasts 30-60 minutes and does not actually address the etiology of the underlying HyperK.
If You Remember Nothing Else
- Most common cause in the hospital is CKD/ESRD (missed dialysis)
- Emergency if > 6.5 mEq/L, clinical findings or EKG change, or an ongoing process causing HyperK
- Temporizing is not necessary in all patients
- Dialyze if all else fails
Here's my favorite review article on the workup and management of hyperkalemia.
pubmed.ncbi.nlm.nih.gov/33160639/
For making it this far, here's the Hyperkalemia Admission One-Pager with a checklist, HPI intake, differential, and sample EHR dotphrase.
You can also find the downloadable PDF on the @pointofcaremed website.