(CNN) -- Kidney stones are intense enough that rocker Vince Neil of Motley Crue had to leave a show Sunday and check into a hospital.
The story about the incident generated a lot of discussion among CNN.com readers who had experienced kidney stones themselves. Wrote Deaux, "I'm a mom of 4 children, and I've had 1 kidney stone. I'd rather have 4 more children than have 1 more kidney stone."
We spoke with Dr. Dianne Sacco, director of Massachusetts General Hospital's Kidney Stone Program, for more information about this condition. The following is an edited version of that interview:
How do you diagnose kidney stones?
One of the most common presentations is the flank pain on one side. It sometimes radiates down into the stomach, and it can actually radiate down into the genital area. That type of pain is pretty commonly seen in stone patients.
Sometimes there's nausea and vomiting. Those type of symptoms are something that gives us a clue that this may be a stone.
The CAT scan is the gold standard for imaging for kidney stones. That's usually the way to diagnose it. You can't do it from a blood test or anything else.
Why do people say that they are so painful?
What it does is, it blocks the flow of urine in the kidney, and it causes backup. And it's an excruciating pain. A lot of people do describe it as worse than childbirth.
When the system is trying to push urine out, what happens is: your kidney and your ureter -- they have this muscle propagation that goes down the kidney into the ureter -- when it's trying to push and the stone is blocking it, you get these intense pains. That's why we call it colicky, it comes and goes and it's extremely painful and the main reason for the pain is the backup of urine.
What's happening exactly?
Usually, if they have two kidneys, they urinate fine, because you're getting urine on the other side. The problem is, that kidney is producing urine but it can't get pushed down.
If you take a pipe and you clog it off and somehow you're still getting fluid into the other end ... if it's a pipe that can expand, it starts expanding.
The backup is like that. It causes a great deal of pain because you're expanding your system. You don't have any pop-off valve. Once it starts expanding, it's expanding unnaturally.
It's called hydronephrosis, and it's basically backup of urine into the kidney.
Are there particular risk factors?
There are certain diseases associated with kidney stones, things like hypoparathyroidism, or some bowel diseases where your absorption isn't normal.
Things like obesity and diabetes are associated with kidney stones. The main dietary factors are low water intake and high salt intake and animal protein -- anything you killed to eat. If you have high amounts of those intakes, it causes your urine to acidify and then it becomes more prone to having stones.
It just depends on the person. If you have a family history, you're more apt to get a stone.
What is the treatment?
If the stones are small enough, they usually pass on their own. Sometimes it can be an uneventful passage, or sometimes it's just an excruciating passage, but we can help them out with pain medicine and some other medicines.
We say greater than 5 mm we start watching them closely. They have a higher chance of requiring surgery to pass the stone.
So it's possible that with pain medicine, it could go away on its own?
Yep, they can pass it. As long as it's small enough, and there's nothing abnormal in their system that prevents it from moving through, if it's small enough people can pass the stones by themselves.
How long does that take?
It can take a few days. Depending on where the stone is and how small it is. Sometimes we monitor up to six weeks, but if the stone isn't progressing, we'll go ahead and take care of it.
If the pain is so much that they can't endure it, then we will go ahead and treat. If their pain is coming and going, and well-controlled with things like ibuprofen or other pain medicine, sometimes we just wait and let them try and pass it.
What does surgery involve?
There are three types of surgery.
There's shock wave lithotripsy -- it's a noninvasive procedure where you basically put shock waves onto the stone externally to break up the stone. That's a good treatment if it works. It requires not as much anesthesia.
The other that we use most commonly probably here is ureteroscopy: taking a little telescope without any incision, you just go up where you pee, go up to the stone, and you use (a) laser to break the stone into pieces.
The much more invasive way is called percutaneous nephrolithotomy, and that's when you go through the back. That's for very large stones.
The incisions are only about 1 cm, and you use telescopes and you basically get into the kidney, onto the stone, with one telescope through the back, and you treat the stone.
If someone has had this once, are they at more risk of having it again?
Definitely. If you have a stone, you do have a much higher risk of getting another stone within the next 5 to 10 years.
What are these stones made of?
About 95% of people have calcium stones. But there are other stones. There (are stones) associated with infection, there's stones associated with acid urine called uric acid stones. There's some medications actually cause stones.
Can stones ever be fatal?
They can. If you have a stone passing down and there's an infection behind it, and the urine can't get out, so the infection sits there, it festers and can be like an abscess and it can actually be fatal if you don't get treated.
Stones can also cause kidney issues. If you leave a stone in there that's blocking your kidney, and it's a chronic condition -- it's been in there for a long time -- usually you see loss of function in that kidney.
Some stones, believe it or not, are completely asymptomatic. People don't even know they have them. It can be a very large stone or a small stone, but they get a CAT scan for some other reason, and that's when we pick it up.
Are you seeing more of these cases?
With the increase in obesity, we know that that's one of our biggest risk factors, and it is increasing in the population. We're seeing more people developing stones. We're seeing more children developing stones. We think this is really largely due to diet.
We're seeing it in all populations. Before, males were highly predominant stone formers versus females. Now females are catching up. And kids had a very low rate of stone disease, and now we're seeing more kids with it. I think diet, the foods we eat, have really been playing a part in the increase we're seeing.