Kidney stones (renal lithiasis) are small, hard deposits of mineral and acid salts on the inner surfaces of your kidneys. Normally, the substances that make up kidney stones are diluted in the urine. When urine is concentrated, though, minerals may crystallize, stick together and solidify. The result is a kidney stone. Most kidney stones contain calcium.
Passing kidney stones can be excruciating. The pain they cause typically starts in your side or back, just below your ribs, and radiates to your lower abdomen and groin.
Painful as they are, kidney stones usually cause no permanent damage. Medical intervention — apart from pain medication — is often unnecessary.
Until a kidney stone moves into the ureter — the tube connecting the kidney and bladder — you may not know you have it. At that point, these signs and symptoms may occur:
- Pain in the side and back, below the ribs
- Fluctuations in pain intensity, with periods of pain lasting 20 to 60 minutes
- Pain waves radiating from the side and back to the lower abdomen and groin
- Bloody, cloudy or foul-smelling urine
- Pain from urination
- Nausea and vomiting
- Persistent urge to urinate
- Fever and chills if an infection is present
Kidney stones that don’t cause these symptoms may show up on X-rays when you seek medical care for other problems, such as blood in your urine or recurring urinary tract infections.