Dear Dr. Roach: I have an enlarged prostate and an overactive bladder. My doctor says not to drink coffee. Can you tell me why not?
Anon.
From the standpoint of your prostate, there is pretty good evidence that coffee tends to reduce the risk of prostate cancer, but there is also weak and conflicting evidence about the effect of coffee on benign prostate enlargement.
In the case of your overactive bladder, there is pretty strong evidence that the caffeine intake of 2 or more cups of coffee can make symptoms worse. (Four or more cups can cause symptoms in people who don’t have a diagnosis of an overactive bladder.) It’s also been my experience with patients that even decaffeinated coffee can be irritating to some bladders, probably due to other chemical compounds in coffee apart from the caffeine.
Your doctor may also be concerned that caffeine is a diuretic, but for most regular coffee drinkers, it takes a lot of coffee — more than 5 cups — to have a diuretic effect. When a person has caffeine for the first time — or if they haven’t had it in a while — it does tend to have a diuretic effect, meaning that you get more out than you put in. But the kidney gets used to that effect quickly, and it eventually wears off.
So, your doctor is just giving you advice to help with reducing your symptoms, but you aren’t harming yourself by drinking coffee. My experience with coffee drinkers is that, for many, minor symptoms are not enough to keep them from having their beloved drink.
Dear Dr. Roach: I just had my second knee replaced. This time, I picked a smart knee. This state-of-the-art knee has an antenna and battery that goes into the femur and sends information about the replacement and the knee to the doctor daily. It’s almost like having a smart watch/Fitbit-type device in the knee.
Unfortunately, this new technology is causing problems. I recently needed an MRI for my back surgery. I went as far as having my hospital gown on and was ready to step into the MRI machine when I asked them about the smart knee. They knew nothing about it and sent me home.
I am still looking for a place that has knowledge of the smart knee and could still do the MRI. In fact, I am trying to find out if it is even safe to get an MRI with a smart knee. Do hospitals have MRIs that can be adjusted for a smart knee?
A.R.
A smart knee is a knee prosthetic that has sensors built into it that record step count, average walking speed, stride length, distance travelled and tibial range of motion for your surgeon. (Note that it doesn’t track your location and uses HIPAA security processes to protect your privacy.) The battery is expected to last 10 years.
I contacted the manufacturer and found that the knee should be safe for MRIs, and I also sent you the technical details that you should give to the MRI technician when you are there.
It’s not yet clear to me if the implantable device has advantages over a wearable device that can tell your surgeon the same information.
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 [email protected]
