Kidney stones (renal lithiasis, nephrolithiasis) are small, hard mineral deposits that form inside your kidneys. The stones are made of mineral and acid salts.
Kidney stones have many causes and can affect any part of your urinary tract — from your kidneys to your bladder. Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together.
Passing kidney stones can be quite painful, but the stones usually cause no permanent damage. Depending on your situation, you may need nothing more than to take pain medication and drink lots of water to pass a kidney stone. In other instances — for example, if stones become lodged in the urinary tract or cause complications — surgery may be needed.
Your doctor may recommend preventive treatment to reduce your risk of recurrent kidney stones if you’re at increased risk of developing them again.
What are the most common types of kidney stones?
There are four main types of stones:
- Calcium oxalate: The most common type of kidney stone which is created when calcium combines with oxalate in the urine. Inadequate calcium and fluid intake, as well other conditions, may contribute to their formation.
- Uric acid: This is another common type of kidney stone. Foods such as organ meats and shellfish have high concentrations of a natural chemical compound known as purines. High purine intake leads to a higher production of monosodium urate, which, under the right conditions, may form stones in the kidneys. The formation of these types of stones tends to run in families.
- Struvite: These stones are less common and are caused by infections in the upper urinary tract.
- Cystine: These stones are rare and tend to run in families.
What are the symptoms of kidney stones?
Some kidney stones are as small as a grain of sand. Others are as large as a pebble. A few are as large as a golf ball! As a general rule, the larger the stone, the more noticeable are the symptoms.
The symptoms could be one or more of the following:
- severe pain on either side of your lower back
- more vague pain or stomach ache that doesn’t go away
- blood in the urine
- nausea or vomiting
- fever and chills
- urine that smells bad or looks cloudy
The kidney stone starts to hurt when it causes irritation or blockage. This builds rapidly to extreme pain. In most cases, kidney stones pass without causing damage-but usually not without causing a lot of pain. Pain relievers may be the only treatment needed for small stones. Other treatment may be needed, especially for those stones that cause lasting symptoms or other complications. In severe cases, however, surgery may be required.