If you’ve never had a kidney stone, consider yourself lucky. When they are eventually passed through the urethra, these jagged, crystalline concretions can cause tremendous discomfort and pain. But apart from the pain, the presence of a kidney stone is often an indicator of other medical conditions. Given that the kidneys do interact with the digestive system, some people worry about the potential trouble kidney stones can cause. But can kidney stones actually affect bowel movements or the digestive system more generally?

An Overview of Kidney Stones

Kidney stones, also known as renal calculi, are essentially hard mineral deposits that can form in the kidneys or urinary system. A common condition in the field of urology, kidney stone disease (nephrolithiasis) affects an estimated 12% of the world’s population. When kidney stones form, their size can vary greatly; they can be as small as a grain of sand, though larger stones can grow to the size of a marble. There are also a variety of types of kidney stones:

  • Calcium oxalate: Kidney stones are most commonly composed of calcium oxalate, a crystalized form of oxalic acid that has bonded to calcium. Such stones can form when the urine simultaneously contains low levels of citrate (a salt of citric acid) and high levels of calcium. Calcium oxalate stones are more likely when consuming excessive amounts of foods that are high in oxalate like black tea, chocolate, nuts, and spinach.
  • Calcium phosphate: Calcium phosphate stones are similarly common, but their formation tends to be related more to abnormalities in the urinary system. In this case, a calcium phosphate stone is more likely to form when the pH level of urine is higher than normal; there are a variety of reasons this may happen, including problems with kidney function where the kidneys don’t properly remove acids from the urine.
  • Struvite: Struvite stones are generally more common in women, but they are overall less common than calcium stones. Made of magnesium ammonium phosphate, struvite stones are typically connected to a previous urinary tract infection (UTI). Whereas other kidney stones can take months to form and pass, struvite stones tend to form in a matter of weeks.
  • Uric acid: Just as struvite stones are more common in women, uric acid stones are more common in men. They typically form when there is an excess of uric acid in the urine, which can happen with a diet high in animal protein or by not drinking enough fluids.
  • Cystine: Cystine stones are rare, and they generally only occur in individuals with cystinuria, a hereditary disorder that causes excessive cystine (a kind of amino acid) in the urine. These stones can form in the kidneys, bladder, or ureters.

Symptoms of Kidney Stones

Many people develop and pass kidney stones without even realizing it. Small stones (usually less than 5 millimeters) typically pass without any symptoms at all, but when they get much bigger, they can become lodged in a ureter, one of the tubes that carries urine from the kidneys to the bladder. A blockage like this can lead to a variety of common symptoms:

  • severe pain or cramping in the side, lower back, or lower abdomen
  • painful and/or frequent urination
  • bloody or foul-smelling urine
  • nausea and vomiting (usually a result of extreme abdominal pain)
  • either an urgent need to urinate or difficulty urinating

Common Causes of Kidney Stones

There are many potential reasons a kidney stone might develop, and the risk factors are related to lifestyle choices, family history, and other medical conditions. What may trigger it in one person may not necessarily trigger it in another. Below are some of the factors that can lead to an increased risk of kidney stones:

  • Dehydration: Inadequate fluid intake can lead to concentrated urine, which is more likely to promote the formation of kidney stones. Staying well-hydrated is one of the most important measures to prevent their development.
  • Diet: As noted earlier, a diet high in oxalates, uric acid (meat and fish), or sodium can greatly contribute to the formation of stones.
  • Medical conditions: Some medical conditions can lead to increased levels of calcium and other substances that make kidney stones more likely. One example is gout, a type of arthritis that causes crystals of uric acid to form around joints; the elevated amounts of uric acid can eventually build up in the kidneys or the bladder.
  • Gastrointestinal issues: Problems in the digestive system can also increase the risk of kidney stones when the absorption of nutrients in the intestines gets disrupted. Examples include irritable bowel syndrome and inflammatory bowel disease (especially Crohn’s disease).
  • Medications: Overuse of medications like diuretics and calcium-based antacids can also increase the risk by disturbing the mineral and electrolyte balance in the body.
  • Lifestyle: People living in hot, arid climates may be at higher risk due to increased fluid loss through sweating. Additionally, people who live a sedentary lifestyle are overall more at risk.

Kidney Stones and Bowel Movements

Even though they are part of the excretory system, the kidneys do interact with the digestive system in an indirect way. The most obvious way is that the digestive system brings in energy that the kidneys use to function. But part of that process involves processing the resulting waste materials. While solids are excreted through the rectum, liquids are filtered through the kidneys before passing through the bladder and urethra. Yet while this connection between the two body systems exists, the connection generally doesn’t include kidney stones.

The only real way that kidney stones can possibly be linked to digestion is in the case of chronic diarrhea. Chronic diarrhea is basically characterized by frequent loose or watery stools over a period of time that lasts at least four weeks. There are numerous possible causes of diarrhea, but one common concern regardless of the cause is dehydration due to abnormally high fluid loss. A person experiencing chronic diarrhea and dehydration will also be more likely to develop kidney stones simply because less bodily fluids means a greater chance of minerals accumulating in the kidneys.

Kidney Stone Treatment Options

Treatment for kidney stones will of course depend on the type of stone, the size, location, and the severity of symptoms. After being diagnosed via X-ray, CT scan, or urinalysis, the doctor will be able to make a determination about the best course of action. In some cases no treatment will be necessary if the stone is small enough. Below are the most common options for treatment when it is necessary:

  • Watchful waiting: Small kidney stones that don’t cause symptoms may pass through the urinary tract on their own. In this case the doctor may recommend waiting to see if pain or other symptoms increase.
  • Medication: Alpha blockers can relax the muscles of the ureters in order to make it easier for the stones to pass. Medication may also be prescribed for the pain or to prevent future stones from forming.
  • ESWL: Short for extracorporeal shockwave lithotripsy, ESWL is a non-invasive procedure that uses shock waves to break kidney stones into smaller pieces that are easier to pass through the urinary tract.
  • Ureteroscope: Ureteroscopy is a minimally invasive procedure that involves passing a thin, flexible tube with a camera through the urethra and bladder to the ureter. Once in place, special tools mounted on the end can remove or break up the stone.

Contact Cary Gastro

Having a kidney stone can be a truly unpleasant experience, and that’s why it’s important to get medical advice as soon as symptoms begin to present. While kidney stones don’t really affect the digestive system, there are numerous ways that what we eat can raise or lower the risk of developing kidney stones or other kidney problems. At Cary Gastro, our compassionate and knowledgeable staff are dedicated to providing excellent healthcare for you and your family. Contact us today to request an appointment.