It’s been bothering me that this question about home potassium measurement hasn’t had a good enough answer, so I worked with Dr. Krishna Priya to do some research on the prospects of an assay we can use for our own self-tracking projects. This assay is especially important for people who have problems with kidney function, are on dialysis, or are dealing with heart disease, but it may also have a range of other uses that we’ll learn more about as it becomes more widely accessible. Here's what I found out.
A NOT TOO COMPLEX BUT EXPENSIVE BLOOD TEST SYSTEM
Potassium can be measured in a number of different ways, all of which have promise for accessible self-measurement tools, but I’ll give the most immediately useful information first, which is that the most immediately accessible tool requires a cartridge lancet blood draw. In this case you need about three drops of blood taken from a finger. A popular and widely accessible (but far from affordable) device available for this purpose is the iStat from Abbott Labs. The i-Stat system is clinically proven (see Papadea et al., 2002) and does not require much clinical training. I would tell you the price, but unfortunately like many medical devices the pricing is opaque. I see supposedly new ones online for prices ranging from $1600 to $15,000. Although these must be different products, they are all have the same or very similar names. I’d appreciate any help that forum members have in sorting this out.
A SUPER PROMISING BUT NOT YET AVAILABLE ECG SYTEM
By far the most promising emerging technology for home potassium measurement is an ECG based assay. There is a direct correlation between changes in blood plasma potassium levels and ECG variations. It has been established that even potassium level fluctuations as low as 0.2mmol/L produced a corresponding quantifiable variation in ECG (see Dillon et al., 2015). An electrode combined with a smart phone was shown to measure potassium levels with 91% efficiency (see Yasin et al., 2017).
This year The Verge reported that long time QS participant Dr. Dave Albert at AliveCor had completed a study with the Mayo Clinic in which their KardiaBand for the Apple Watch succeeded in measuring potassium levels. (See this story: “Apple Watch wristband sensor claims to detect potassium in your blood, without needle, but it doesn’t have FDA approval yet.”) But there is no release date for Potassium testing KardiaBand.
(So, Dr. Dave, can you tell us anything?)
AN OFF LABEL SALIVA BASED TEST OF UNCERTAIN VALIDITY
Potassium can also be measured in saliva. For those of you who enjoy quests of this nature, check out the claims in this document by instrument maker Horiba, based in Singapore, that it’s water quality measurement tool, the Laqua Twin, can also be used for measurement of potassium levels in humans.
See their pamphlet here: Monitoring Human Potassium With Laqua Twin.
It appears that the instrument is available on Amazon, and from the comments some buyers are making use of it for home potassium testing.
See this Amazon link and scroll down for comments: HORIBA LAQUAtwin 3200456566 Model B-731 Compact Potassium Ion Meter.
If any of these pointers are useful for you, please let us know. And definitely let us know if you think we’ve gotten anything wrong, or if you can add any first hand experiences of your own.
PS: I didn’t look too deeply into urine test strips. These exist, but the information was too sketchy for me to easily evaluate.