What are kidney stones?
Your kidneys are responsible for removing excess fluid from your body and filtering out unneeded electrolytes and wastes from your blood, resulting in the production of urine.
Kidney stones form when the minerals and acid salts in your urine crystallize, stick together, and solidify into a mass. This happens when your urine contains more crystal-forming substances, such as calcium and uric acid, than the available fluid can dilute. This can happen when urine is highly acid or highly alkaline.
A kidney “stone” (as you can see from the pictures they are not actually stones) is a solid mass made up of tiny crystals. One or multiple stones can be in the kidney or ureter at the same time. The main symptom is severe pain that starts suddenly and may go away.
How do kidney stones occur?
The conditions allowing kidney stones to form are created by problems in the way your body absorbs and eliminates calcium and other substances. Sometimes the underlying cause is a metabolic disorder or kidney disease.
Certain drugs can also promote kidney stones, such as Lasix (furosemide), Topomax (topiramate), and Xenical, among others. Many times, it is a combination of factors that create an environment favorable to stone formation.
Four Types of Kidney Stones
Most kidney stones contain crystals of multiple types. However, usually one type predominates, and determining the type helps you identify the underlying cause:
1. Calcium stones.
The most common type (four out of five cases) is usually in the form of calcium oxalate. Oxalate is found in some fruits and vegetables, but your liver produces most of your oxalate. If you are found to have oxalate stones, your doctor may recommend avoiding foods rich in oxalates, such as dark green vegetables, nuts and chocolate.
2. Struvite stones:
Found more often in women, these are almost always the result of urinary tract infections.
3. Uric acid stones.
These are a byproduct of protein metabolism. They’re commonly seen with gout, and may result from certain genetic factors and disorders of your blood-producing tissues.
4. Cystine stones.
Represent a very small percentage of kidney stones. These are the result of a hereditary disorder that causes your kidneys to excrete massive amounts of certain amino acids (cystinuria).
Symptoms
You won’t know you have a stone until it moves into the ureter—the tube connecting your kidney and your bladder. Common symptoms include:
- Pain in your side and back, below your ribs,
- Episodes of pain lasting 20 to 60 minutes, of varying intensity
- Pain “waves” radiating from your side and back, to your lower abdomen and groin
- Bloody, cloudy or foul-smelling urine
- Pain with urination
- Nausea and vomiting
- “Urgency” (persistent urge to urinate)
- Fever and chills (indicates an infection is also present)
The pain is a result of distention of the tissues above the stone, since it is blocking the passage of urine, rather than from the pressure of the stone itself.
When to see a doctor
As soon as you have any of the above symptoms.
Resource Center:
Popularity: 7% [?]

