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PSA Blood Tests

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Sheldon Marks, MD - Blogs
By Sheldon Marks, MDBoard-certified urologistDecember 07, 2005
From the WebMD Archives

For years I have been talking about the relative inaccuracy of the PSA blood test. Yet I still believe it continues to save tens of thousands of lives each year. An elevated PSA saved the lives of many of my own patients more than 10 years ago – and they are alive and healthy today.

I still hear of situations where patients and even doctors misinterpret the PSA results. They don’t seem to understand what the PSA is and what it isn’t. For reasons that I think are totally human, doctors as a group seem to empower the PSA result with far more significance than it really deserves, or was ever intended to have. And just last week the perfect example occurred in my office. In fact, so good it begged to be described in this “mediblog,” which sounds so much better than a “blogomed.” Let me explain.

It all started with a follow-up visit with a patient. Let’s call him Jim. He is a 72-year-old very healthy retired business executive. Very smart, very Internet savvy. Jim has had an elevated PSA for many years. Not dangerously high but enough to be of some concern. Yes, he has had several rounds of ultrasound-guided biopsies, all of which show no evidence of any cancer or even any precancerous PIN or atypia. Even with the risks for sampling error, the odds are good he does not have any large or significant cancer lurking in there. Still, we are following him with regular PSA levels and exams. Just to be sure.

Two weeks ago he had his PSA level drawn. Of interest, he had it drawn at two labs. Why, he isn’t sure. He had the PSA drawn that our office ordered and then Jim went to his primary doctor who drew more blood and added on a PSA level, not knowing about the prior draw 30 minutes before. Here’s the part that caused him some confusion. The results came back – one result at 7.2 and one at 8.4 – both from reputable labs, using state-of-the-art equipment. Both tests were drawn the same day, same patient, same hour. “How could this be?” he asked. “Is it going up that fast or is it dropping rapidly? What could I have done in 30 minutes that raised it or dropped it so much?”

“Aha”, I said smiling like I knew a secret I was about to share. “Just as I expected.” After his 15-second digital prostate exam was completed to confirm nothing had changed in 6 months, I explained what I have been saying for many years and have even written about in my book (yes, this is a plug, and a well-timed one at that). The PSA is a test of the prostate, not prostate cancer.

It is not an exact test, nor was it ever intended to be. The level can vary from day-to-day, lab-to-lab. It should be viewed as a ballpark test–information to be used in conjunction with the rest of the exam, history, and past results. Minor fluctuations are not only common, they are the norm. A PSA of 2.8 is the same as a PSA of 3.1 or 2.5. But despite my saying this over and over, year after year, people still look at their own levels as if they are precise results. They would see a change from 4.5 to 4.6 as a major sign of rapid and fatal cancer progression.

Now, though, I have a great example to demonstrate the fact that PSA is indeed a ballpark result. In fact, it is a nonspecific ballpark result so you can’t even tell which ballpark it is in. Sure, it could represent a prostate cancer. It could also suggest prostate enlargement, infection, or recent injury such as a catheter placement or even a recent prostate biopsy (you should wait at least 8 to 12 weeks after a biopsy to recheck PSA). Sometimes it is just elevated.

If the PSA is elevated or goes up should you worry? Yes, a bit. If it is a concern, always ask to have it checked again in a few weeks. Then, if it is still up significantly or moving up, and your urine shows no sign of infection, it is time to see the urologist. No, you cannot wait 6 months. Call and make the appointment. It is a no-lose situation. If you have a cancer, then you usually catch it early and can decide what to do while you still have choices. Letting it grow just eliminates options, and shortens your lifespan. It’s more likely that there will be no cancer and then you can quit worrying about the PSA level. And then, as most guys do, you can look for something else to stress about or ignore.

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About the Author
Sheldon Marks, MD

Sheldon Marks, MD, is director of the International Center for Vasectomy Reversal in Tucson, one of the leading specialty centers in the world. Dr. Marks is a best-selling author and frequently teaches other urologists about advances and techniques with vasectomy reversals. He has been writing for WebMD since 2005.

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