Q. A friend of mine is a T12 para. It seems about every four or five years he ends up with a major kidney stone that needs to be removed, sometimes with a high tech procedure where they zap the stone with sound waves, other times with a fairly serious sounding surgery.

He says it becomes obvious when he has a kidney stone that starts to move because he gets a massive stabbing pain in his lower back — on whichever side the kidney stone is — that sends him straight to the ER.

I’m a C6 complete quad. If I had a kidney stone, I wouldn’t be able to feel any stabbing pain in my back. Are there other symptoms that show up with a kidney stone? How can you tell if you have one? Is there a way to tell if you have one before gets to the point of needing surgery? And what would happen if you didn’t have a stone removed?

—Stan

A. Kidney stones are a serious deal, and larger stones can get stuck, which can cause permanent kidney damage. A literature search shows that about 10 percent of all people will have a kidney stone in their lifetime; it also shows if you get one stone you are likely to get another.

Smaller kidney stones may pass unnoticed, and stones that are stable — in the kidney but not moving — may be symptom free. When a larger stone passes it can cause severe pain in the lower back, side or abdomen — often described as sharp, severe, intermittent pain, that doesn’t improve by changing body position — the kind of pain that will make a person race to the ER.

According to Paula Wagner, a urology nurse practitioner from U.C. Davis Medical Center in Sacramento, Calif., other symptoms of a passing kidney stone, or one that gets stuck, include blood in the urine, nausea, vomiting, and urinary tract infection. If you have a spinal cord injury, add dysreflexia and increased spasms to the symptom list.

The best way to avoid this kind of trauma is to catch a kidney stone it when it is small. If it does need to be removed, the smaller the stone, the better the options to remove it.

Wagner says U.C. Davis recommends people with SCI have a yearly ultrasound as well as a KUB — kidney, ureter and bladder X-ray —