What are Kidney Stones?

What are Kidney Stones?

  • Kidney stone illustration

What are Kidney Stones?

Urine contains many dissolved minerals and salts. When your urine has high levels of these minerals and salts, you can form stones. Kidney stones can start small but can grow larger in size, even filling the inner hollow structures of the kidney. Some stones stay in the kidney, and do not cause any problems. Sometimes, the kidney stone can travel down the ureter, the tube between the kidney and the bladder. If the stone reaches the bladder, it can be passed out of the body in urine. If the stone becomes lodged in the ureter, it blocks the urine flow from that kidney and causes pain.

What are the Signs of Kidney Stones?

Stones in the kidney often do not cause any signs and can go undiagnosed. When a stone leaves the kidney, it travels to the bladder through the ureter. Often the stone can become lodged in the ureter. When the stone blocks the flow of urine out of the kidney, it can cause the kidney to swell (hydronephrosis), often causing a lot of pain.

Common symptoms of kidney stones are:

  • A sharp, cramping pain in the back and side, often moving to the lower abdomen or groin. Some women say the pain is worse than childbirth labor pains. The pain often starts suddenly and comes in waves. It can come and go as the body tries to get rid of the stone.
  • A feeling of intense need to urinate.
  • Urinating more often or a burning feeling during urination.
  • Urine that is dark or red due to blood. Sometimes urine has only small amounts of red blood cells that can’t be seen with the naked eye.
  • Nausea and vomiting.
  • For men, you may feel pain at the tip of the penis.

What Causes Kidney Stones?

  • Low Urine Volume – Low urine volume may come from dehydration from hard exercise, working or living in a hot place, or not drinking enough fluids. When urine volume is low, urine is concentrated and dark in color. Increasing fluid intake will dilute the salts in your urine. By doing this, you may reduce your risk of stones forming.
  • Diet – One of the more common causes of calcium kidney stones is high levels of calcium in the urine. High urine calcium levels may be due to the way your body handles calcium. It is not always due to how much calcium you eat. Lowering the amount of calcium in your diet rarely stops stones from forming. Instead of lowering dietary calcium intake, your health care provider may try to reduce your urine calcium level by decreasing your sodium (salt) intake. Too much salt in the diet is a risk factor for calcium stones. This is because too much salt is passing into the urine, keeping calcium from being reabsorbed from the urine and into the blood. Reducing salt in the diet lowers urine calcium, making it less likely for calcium stones to form.
    Because oxalate is a component of the most common type of kidney stone (calcium oxalate), eating foods rich in oxalate can raise your risk of forming these stones. A diet high in animal protein, such as beef, fish, chicken and pork, can raise the acid levels in the body and in the urine. High acid levels make it easier for calcium oxalate and uric acid stones to form. The breakdown of meat into uric acid also raises the chance that both calcium and uric acid stones will form.
  • Bowel Conditions – Certain bowel conditions that cause diarrhea (e.g. Crohn’s Disease or ulcerative colitis) or surgeries¬† (such as gastric bypass surgery) can raise the risk of forming calcium oxalate kidney stones. Diarrhea may result in loss of large amounts of fluid from the body, lowering urine volume. Your body may also absorb excessive oxalate from the intestine, resulting in more oxalate in your urine. Both low urine volume and high levels of urine oxalate can help to cause calcium oxalate kidney stone formation.
  • Obesity – Obesity may change the acid levels in the urine, leading to stone formation.
  • Medical conditions – Abnormal growth of one or more of the parathyroid glands, which control calcium metabolism, can cause high calcium levels in the blood and urine. This can lead to kidney stones. Another condition called distal renal tubular acidosis, in which there is acid build-up in the body, can raise the risk of calcium phosphate kidney stones.
    Some rare, inherited disorders can also make certain types of stones more likely. Examples include cystinuria, which is too much of the amino acid cystine in the urine, and primary hyperoxaluria, in which the liver makes too much oxalate.
  • Medication – Some medications, and calcium and vitamin C supplements, may increase your risk of forming stones. Be sure to tell your health care provider all the medications and supplements you take, as these could affect your risk of stone formation. Do not stop taking any of these unless your health care provider tells you to do so.
  • Family History – The chance of having kidney stones is much higher if you have a family history of stones, such as a parent or sibling.

How are Kidney Stones Diagnosed?

“Silent” kidney stones, those that cause no symptoms, are often found when an X-ray is taken during a health exam. Other people have their stones diagnosed when sudden pain occurs while the stone is passing, and medical attention is needed.

When a person has blood in the urine (hematuria) or sudden abdominal or side pain, tests like an ultrasound or a CT scan may diagnose a stone. These imaging tests tell the health care provider how big the stone is and where it is located.

A CT scan is often used in the ER when a stone is suspected. It is used because it can make a quick and exact diagnosis.

How are Kidney Stones Treated?

Treatment depends on the type of stone, how bad it is, and the length of time you have had symptoms. There are different treatments to choose from. It is important to talk to your health care provider about what is best for you.

  • Often you can simply wait for the stone to pass. Smaller stones are more likely than larger stones to pass on their own. While waiting for the stone to pass, you should drink normal amounts of water. You may need pain medication when there is discomfort.
  • Certain medications have been shown to improve the chance that a stone will pass. The most common medication prescribed for this reason is tamsulosin. Tamsulosin (Flomax) relaxes the ureter, making it easier for the stone to pass. You may also need pain and anti-nausea medicine as you wait to pass the stone.
  • Surgery may be needed to remove a stone from the ureter or kidney if:
    • The stone fails to pass.
    • The pain is too great to wait for the stone to pass.
    • The stone is affecting kidney function. Small stones in the kidney may be left alone if they are not causing pain or infection. Some people choose to have their small stones removed. They do this because they are afraid the stone will unexpectedly start to pass and cause pain.
    • Kidney stones should be removed by surgery if they cause repeated infections in the urine or because they are blocking the flow of urine from the kidney. Today, surgery usually involves small or no incisions (cuts), minor pain and minimal time off work.

The information in this post is an excerpt from an article published by the Urology Care Foundation.

For tips on avoiding kidney stones, check out our blog post “Tips for the Prevention of Kidney Stones”.

If you have questions or concerns about kidney stones, contact the Urology Group of Princeton to schedule an appointment. The board certified physician/surgeons at the Urology Group are highly trained to evaluate your symptoms, perform applicable tests, and develop the proper treatment plan.