San Antonio Express-News (Sunday)
Score for kidney function usually drops with age
Q: Each year when I receive results from my yearly blood work I notice that my GFR score keeps going down. This year is the first year that my score dropped below 60, with a score of 57. I am 66 years old, and there are no other scores in my blood work that would indicate kidney disease. My doctor keeps telling me to just drink more water. I take amlodipine/benazepril for my blood pressure. Should I be concerned and have further tests? Is the blood pressure medication causing my GFR score to be low?
A: GFR, the glomerular filtration rate, is a measure of kidney function, with the higher the number meaning the greater the kidney function. It’s calculated using a person’s age and sex, and the measured creatinine in the blood. Creatinine is cleared from the blood by the kidneys, so the lower the creatinine, the higher the GFR and the better the kidney function.
Kidney function slowly goes down as we age, but the rate of decline is important. The average GFR for a person in their 60s is about 85, but you are on a medication (benazepril) that lowers the GFR number. In the kidney, benazepril (a class of medication called an ACE inhibitor) decreases blood flow to the filtering parts of the kidney, the glomeruli, and creatinine always goes up. However, ACE inhibitors are excellent at protecting kidney function in people with many kinds of kidney disease. Stopping it would make the number look better but would rob you of the protection the medication is giving you.
Your regular doctor can tell you whether your rate of GFR decline is worth worrying about. If not, a kidney specialist will certainly do so. It is wise to look carefully at your other medicines, if any, especially including over-the-counter pain medicines, to make sure none of them could be harming your kidneys.
Q: I’d like your advice on a new prescription drug, vibegron, for reducing prostate enlargement when taken along with tamsulosin. Should I be concerned about any side effects that you might be aware of ? I’m considering participating in the study since I’m currently taking tamsulosin with no side effects.
A: Vibegron (Gemtesa) is a newer drug used for symptoms of overactive bladder. It activates receptors (called beta-3 receptors) in the bladder that then relax the bladder wall and increase bladder capacity.
Vibregon doesn’t affect the prostate at all. However, men with lower urinary tract symptoms are often assumed to have prostate enlargement as the underlying cause, when in fact, they may have overactive bladder in addition to (or even instead of ) an enlarged prostate. Tamsulosin (Flomax) relaxes muscle tone inside the prostate, allowing for better urinary flow.
A study published just last year showed that adding vibegron to a prostate treatment such as tamsulosin improved some symptoms of overactive bladder. Often, patients get incomplete relief from treatment of enlarged prostate before seeing a urologist to treat overactive bladder with great improvement.
Side effects of vibegron, like other beta-3 agonists, are generally mild. Some men have had an increase in the blood pressure with mirabegron (the other available beta-3 agonist), so that is worth keeping an eye on.
Q: I am a healthy 77-yearold male. I’m 5 feet, 7 inches tall and weigh 145 pounds, with difficult-to-control high blood pressure. For many years I had a blood pressure reading around 140/80 with no medicines. Last year I had a very severe headache, and I thought it might be a stroke or TIA. I had a reading over 180/100 and was diagnosed with high blood pressure.
My family doctor started me on hydralazine at 50 mg twice a day, then 50 mg three times a day. My blood pressure still fluctuated, and I was prescribed 5 mg of clonidine to take as emergency medication for anything
over 180/100. Later, metoprolol 50 mg daily was added, then 80 mg telmisartan, then a few months later 5 mg amlodipine. It was not until I started taking the amlodipine that my blood pressure was finally controlled. My morning readings are better and then elevate throughout the day. My kidneys and heart are all healthy with no specific cause for the high blood pressure found.
What are your thoughts regarding the hydralazine? It is inconvenient to take three times a day, and I wonder about the roller coaster of the medicine’s effects given its short half-life. Its long-term side effects are concerning.
Once my BP was controlled, I reduced the hydralazine down to 25 mg, after which I saw a slow gradual increase in my average blood pressure, so I went back up to 50 mg. Now my blood pressure seems to be fluctuating even more, with morning readings around 125/80 and afternoon readings around 160/ 85.
My nephrologist recommended I try stopping the hydralazine and instead add an additional 40 mg of telmisartan taken in the morning. My family doctor is of the opinion that because I am under control at the moment, I should change nothing.
Can hydralazine be stopped suddenly? I see conflicting information online, and my doctors have differing opinions. Is there a typical replacement medicine for hydralazine?
A: The best blood pressure regimen is the one that best controls blood pressure with no side effects. However, your regimen is quite unusual.
Hydralazine is very seldom given for high blood pressure anymore. Sometimes it is given to people with heart failure in very specific instances. For example, if a person were hospitalized for a high blood pressure emergency. You’re right about its long-term side effects being concerning. It is the most frequent cause of drug-induced lupus and can also cause vasculitis (blood vessel inflammation). Because of the potential for serious side effects and the inconvenient dosing schedule, it is not often turned to as a medicine for high blood pressure.
I am also concerned about the use of as-needed drugs like clonidine for arbitrary high blood pressure numbers. It’s never been clear that it helps, and it might cause the blood pressure to drop greatly enough to reduce brain blood flow. I am not a fan of this regimen.
Hydralazine and the amlodipine you are already taking work using a similar mechanism, as does the telmisartan. Since you’re not at the highest doses of either, I would favor slowly tapering the hydralazine and increasing one of the other drugs. Both last much longer in the body than hydralazine, with less risk of side effects.