To Your Good Health
DEAR DR. ROACH: I’m 77 and have an enlarged prostate. My PSA score has been between 5.2 and 5.9 ng/mL for years. Recently, my internist had me take a PSA test, and it was 9.5 ng/mL. Two weeks later, my urologist did another test, and it was 5.7 ng/mL. The two tests were done by different lab groups. Are PSA scores calculated differently by different labs? — T.W.
ANSWER: Yes, there are several different manufacturers who make devices to measure PSA levels, and each is slightly different. A 2021 study evaluating three of the most common devices showed that they were very similar (within 0.5 ng/mL of each other).
In the past, they were not always compatible. The advice was to use the same lab to compare one level with another, but it appears that this has become less important, at least with the devices that were tested.
There are some reasons why PSA scores can suddenly become elevated. Inflammation or infection of the prostate can cause very large increases. I’d be surprised if that were the case, as it is likely you would have had symptoms. Your level also decreased faster than I would expect it to without treatment. Trauma to the area, such as surgery, will also cause PSA scores to rise. Bike-riding was shown to increase PSA levels in some studies. Sexual activity raises PSA scores by an average of 0.5 ng/mL. A finger exam has negligible effects on a PSA score as well.
There are times that labs can be spuriously high without an identifiable reason, and rechecking is always wise before making a clinical decision, especially when the change is unexpected.
DEAR DR. ROACH: I am a healthy 60-year-old woman of average height and weight with a single functioning kidney. (The other never developed due to a congenital defect and is nonfunctioning.) I’ve never had any issues with the kidney that works (even when pregnant), and tests have shown that it functions normally without the presence of disease or impairment.
With the exception of fish, I have eaten a plant-based diet for 40 years, have low blood pressure and limit my salt intake. My creatinine levels and other lab results are all normal. I do not take any medication.
Here’s my question: Given my single kidney status, is it okay to drink 2-3 cups of caffeinated tea daily, or should I refrain? People in my family are long-lived (over 90), and I’d like to retain normal kidney function for the rest of my life.
I’m concerned that as I get older and naturally lose kidney function, drinking caffeinated tea may accelerate this loss or possibly even lead to dialysis 30 years from now. How likely is this, and do you have any kidney health suggestions? — P.S.
ANSWER: Drink your tea with a clear conscience. There isn’t good evidence that tea or caffeine in reasonable amounts is harmful to kidneys, and there’s some evidence that it may even be helpful at preventing kidney disease.
A plant-based diet, low salt and avoiding too many medicines that are harmful to the kidney — such as high-dose ibuprofen over the span of many years — are all great ways to protect your single kidney.
EDITOR’S NOTE: Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.