Are there specific symptoms? Yes; symptoms of kidney stones include extreme pain in the back, flank, and groin on the affected side, bloody urine, vomiting, and sometimes frequent, difficult or painful urination. Generally, people who've never had a kidney stone pass before are totally unaware of it until it starts to move and they're slammed with the unbelievable pain.

Kidney stones are crystals made up of substances that pass through the urinary tract. The most common type of stone is calcium oxalate, but people can also get uric acid, calcium phosphate, and struvite stones. Normally, these substances remain dissolved in urine, but when they're present in particularly high quantities or if the urine is concentrated, crystals can form. If the condition that allows the crystals to form isn't corrected (by drinking more water, for example), those crystals can grow until a stone is formed.

Treatment depends on the situation. Once a stone is diagnosed, as long as it's not too large (generally smaller than 5 mm in diameter), the doctor will usually recommend an appointment with a urologist and lots of fluids. Pain medication is also prescribed. With plenty of fluids, most small stones pass on their own within a few days. If the stone is large, if it's causing an obstruction, or if it's not passing naturally, there are a few options. Lithotripsy is usually the first choice since it's the least invasive and least traumatic procedure. Shock waves are directed at the stone to break it into fragments that are more easily passed. If lithotripsy isn't an option (usually because the stone is too dense to break up or not dense enough to see on x-ray), other options might be ureteroscopy, where an endoscope is threaded up into the urinary tract to extract the stone or percutaneous nephrolithotomy, where a large needle punctures the kidney to provide a route for extracting the stone.

Once the stone is out, the doctor will discuss prevention. Prevention will depend on the chemical makeup of the stone, but one preventive common to all kidney stones is lots and lots of water. If diet is playing a part, dietary restrictions (such as low-oxalate foods) are recommended. Other possible treatments include magnesium and potassium supplementation, citrate supplementation (either in lemonade or as magnesium citrate/potassium citrate), low protein diets and thiazide diuretics. Urologists will also order a 24-hour urine collection test to help identify the specifics of your stone disorder.

You asked about coffee. Studies show that coffee actually lowers the risk of kidney stones, although caffeine use has been linked to increased urinary calcium, which can potentiate stone formation. (Here's a link to one study abstract: http://aje.oxfordjournals.org/content/143/3/240.abstract .)

If you suspect you have a kidney stone, get yourself to your doctor's office or emergency room right away. For one thing, they can provide pain killers -- a necessity for someone passing a stone! -- and they can also order images to make sure that the stone isn't obstructing your urinary tract. Trust me: I've had hundreds of kidney stones in my life, and they're nothing to fool around with.