My comments here pertain to telmisartan ™. It is the only sartan I have taken. For me, TM comes close to being a wonder drug like metformin in terms of its many and synergistic contributions to healthspan. If my wife’s BP were not already in the low normal range, I would suggest that she take it. Most of my comments are likely true of other ARBs to varying degrees…
While TM significantly slows the rate of decline in GFR as it becomes manifest in adults 65 years and older – the focus of these comments – it also provides a useful diagnostic indicator of another important kidney function. ARBs lower blood pressure and protect the kidneys by blocking the action of angiotensin II. A downstream effect of this is a reduction in aldosterone. Aldosterone’s primary job in the kidney is to promote sodium retention while simultaneously promoting potassium excretion in the distal tubules. By reducing aldosterone, ARBs also cause the body to retain (excrete less) potassium. This is why those who take the drug are urged to monitor their potassium levels and adjust their diet if necessary. However, even among older adults, some who take the drug will not experience elevated serum potassium. When an older adult’s potassium level remains normal despite taking a full dose of TM, I believe it implies that their distal tubules and collecting ducts are still highly functional; i.e., they have enough cellular machinery and responsive capacity to excrete potassium effectively, even with a diminished aldosterone signal. I see this as a sign of renal resilience. While their filtration (GFR) may be declining, their secretory mechanisms remain robust which suggests a favorable overall prognostic indicator.
Whether or not elevated potassium becomes an issue when taking TM, monitoring and managing kidney function and BP with TM can take on another dimension if urine PH tends toward the high end, as is possible along with other causes with diets high in animal, grain, and egg proteins. In addition to increasing the risk of certain kinds of kidney stones, acidic urine stresses kidneys in ways that can become critically important for older adults. A negative spiral can develop and can quickly become difficult to manage because the standard methods of lowering the kidney stressing PH can also stress the kidneys. Changing the diet may be the safest method for improving PH but it might also be the most difficult path due because it is also important for older adults to consume adequate levels of protein. Potassium citrate is a simple and generally safe method of improving acidic PH but in older adults it can stress the kidneys through a buildup of potassium. Sodium bicarbonate is also effective of bringing PH into an optimal range but, again, it stresses the kidneys with additional sodium.
These comments are based solely on my personal experiences, research, and discussions with other older adults taking TM.
Thank you, RobTuck for this thoughtful post. I am just starting my telmisartan journey - currently on 20mg/day - so I have nothing to report atm, other than somewhat slightly lower BP numbers. I intend to move to 40mg and if possible, 80mg down the road. The problem is that already right now, I can dip as low as S93/D62 in the morning, so I’m a bit concerned if I have enough headroom to go to 40-80mg.
Regarding potassium, I will have a blood and urine panel at the end of October, but my potassium is toward the upper end of the range, so not a whole lot of room there either. Interestingly, in the past, I’ve occasionally gone above the ref. range on potassium and my PCF had me redo the test where it came back within range. This tells me, that if I now have a higher reading on potassium, I cannot automatically put it down to telmisartan as the cause - in other words, your “test” may not be so unambiguous. The other thing is that my serum sodium readings are above the ref. range while the rest of my kidney related biomarkers are fine. I’m curious to see if telmisartan will affect my sodium readings.
Now I’m debating how high a dose I should take before the test, so that when I get the numbers back, they can reflect the final dose. It is also my understanding that going above 80mg there is no further impact on BP, but there may be some positive impact on other health aspects, so it may make sense if you take 80mg to just as well take 160mg. Of course, that’s assuming that nothing crazy happens with potassium with telmi above 80mg, or other side effects - I’ve looked at the literature but can’t find anything specifically addressing this.
Your situation illustrates the complexity of kidney dynamics. Elevated potassium and sodium each add stress to the kidneys, presumably accelerating aging. I don’t know if the combination, if that were true in your situation, would be additive or play out at a higher level. At the same time, I infer that your eGFR or CystA indicate normal filtration so your goal going forward on this point would be to slow the inevitable age-related rate of decline enough that your kidney function will not be the first end-of-life signal. Assuming at least and age-normal eGFR now, telmisartan will do that and will convey the other benefits we discussed. But a conk on the head is not worth the GFR gain. SGLT2 inhibitors will slow the rate of GFR decline by a similar amount. That may be a safer path for you, although the side effects are more consequential, whereas TM’s side effects are typically minimal to non-existent.
Based on my superficial analysis, I think my first goal would be to identify and resolve the causes of elevated potassium and sodium, if they exist as a stable pattern. Assuming you use a certified lab, these mineral tests are simple and it is extremely unlikely that the test value are incorrect.
Yes, you are correct. I would love to track down the reason(s) for my (above ref. range) high sodium and chloride and high (but still just at the upper ref. range most of the time) potassium readings. This has been a steady pattern for, at this point, decades. As the rest of my kidney related readings are excellent, both serum and urine, it’s a puzzle. My PCP is of course useless. I had a vague theory that perhaps it’s somehow related to the 18-20 hour dry (no liquids) fasts not just prior to the tests, but daily. However, the urine test doesn’t seem to indicate volumetric issues, so it’s not dehydration as such - perhaps something else. Having done a lot of reading on hypernatremia, none of the usual scenarios apply at all. I do have one fairly large cyst on one of my kidneys, but otherwise both have normal images.
As to SGLT2i, I’m on empagliflozin 25mg/day. I’ve been doing it for six months and another six prior of 12.5mg/day.
Yes, my one fear with higher dose telmisartan is hypotension, and blood flow to the brain, which is a very big issue for those of us above 65 years of age (I’m 67). For the elderly, that is one reason (plus falls), why doctors are willing to tolerate mild hypertension, as hypotension related blood flow to the brain is the real danger. Dementia is my #1 fear. I’m hoping regular exercise might be helpful in this respect, plus highish daily intake of caffeine (coffee and tea).
I am proceeding carefully with telmisartan, regularly checking BP, and watching any possible effect stacking on BP with empagliflozin, pioglitazone etc.
I am not thinking of any kidney related benefits of telmi specifically (though I’ll gladly take them, if present!), rather cardiovascular and lipids and other possible ones (longevity signal of BP drugs in animal models).