Kidney stones form due to an imbalance between the water and dissolved minerals and salts in urine that causes them to crystallize into little jagged stones. Passage of a kidney stone can be extraordinarily painful, but fortunately it usually does not require any treatment beyond pain medication, nor does it usually cause any permanent damage.
History
The National Institute of Diabetes and Digestive and Kidney Diseases (NDDK) tells us that kidney stones have plagued humans for millennia. One study found kidney stones in a 7,000 year old Egyptian mummy. The Merck Manual tells us that these days, 1 in 1000 Americans per year needs hospital care for symptoms of kidney stones.
Size of Stones
Kidney stones can range in size from microscopic aggregates to small spiky pebbles of more than 5 mm in diameter. Even large stones that stay within the kidney generally do not cause any symptoms, unless they create a blockage. Symptoms occur when the stones pass into the ureter, which is the tube leading from the kidneys to the bladder. The Merck Manual says that stones smaller than about 5 mm in diameter usually pass through the ureter spontaneously, though not without causing pain, while larger stones can lodge in the ureter, causing pain and disrupting kidney function.
Early Symptoms
According to the Merck Manual, some kidney stone patients first notice some blood in the urine, or the urine might contain tiny granules. Other early signs like cloudy or foul smelling urine, fever and difficulty urinating might be confused with a urinary tract infection. More often though, severe pain is the first symptom, says the NIDDK.
Other Symptoms
When a kidney stone passes into the ureter, its jagged edges irritate the tube and can cause excruciating pain. The pain typically comes in waves that last 20 to 60 minutes, says the Merck Manual. During the waves of pain the patient writhes or paces, unable to find a comfortable position. Most patients feel nauseated and vomit, and they look pale and sweaty. If the stone lodges in the ureter, back pressure on the kidney can cause a sensation of bloated pain and pressure and urine output decreases. For stones that can pass spontaneously, the worst pain stops once the stone passes out of the ureter and into the bladder. The passage of the stone can take from hours to days, but can be hastened if the patient drinks plenty of water. Large or lodged stones might require surgical removal or treatments to break them into smaller pieces.
Site of Pain
Pain from a kidney stone can affect the flank (side of the ribcage) or the back just below the ribs, and spread to the lower abdomen and groin. The Merck Manual says that the site of pain charts the stone's journey through the ureter. Pain in the flank or the area of the kidneys indicates that the stone is in the upper end of the ureter. Pain in the area above the pubic bone indicates that the stone has reached the junction of the ureter with the bladder.
