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By: Stacy Wiseman, RD LD
Kidney stones, also known as renal calculi, urolithiasis or nephrolithiasis are small hard deposits that form in one or both kidneys. Kidney stones can form when the urine becomes too concentrated with certain minerals, salts, or other substances. They can range in size from very small, like a grain of sand to the size of a golf ball. Some kidney stones may go undetected, but others can cause excruciating, unforgettable pain.
Signs and Symptoms:
Severe, sharp pain in the side and back, below the ribs.
Pain that radiates to the lower abdomen and groin.
Pain that comes in waves and fluctuates in intensity.
Painful or burning sensation during urination.
Urgency and frequency to urinate.
Pink, red, or brown urine.
Cloudy or foul-smelling urine.
Nausea and vomiting.
Fever and chills can indicate the presence of an infection.
Risk Factors:
Family or personal history of kidney stones: If you or a family member has had kidney stones, you are more likely to develop a stone.
Dehydration: Excessive sweating or not drinking enough water can increase your risk for kidney stones.
Diet high in protein, salt, or sugar: Studies have shown that eating a diet that's high in sodium can increase your risk of certain types of kidney stones. Too much sodium in your diet increases the amount of calcium your kidneys must filter and significantly increases your risk of kidney stones. In addition, diets that are high in protein and sugar can increase your kidney stone risk. Your urine may lack citrate, which is known to prevent crystals from sticking to one another, creating an ideal environment for kidney stones to form. For most patients, a low-protein, low- sodium, and moderate-calcium diet is recommended.
Obesity: High body mass index (BMI), large waist size, and weight gain have all been associated with an increased risk of a single episode and recurrent episodes of kidney stones.
Digestive diseases or surgeries: Certain disorders of the digestive system can affect calcium, electrolyte, and water absorption, which may increase your risk of forming kidney stones. Common disorders include gastric bypass surgery and inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis.
Other medical conditions: Conditions such as high blood pressure, diabetes, and cystinuria may increase the risk for kidney stones.
Types of Kidney Stones and Nutrition Intervention:
1. Calcium Oxalate stones are the most common type of kidney stone and result from too much
oxalate in the urine. Oxalate is a natural substance found in foods such as nuts, rhubarb,
spinach, and beets. These types of stones can form when the urine is concentrated with waste
and not enough liquid is present causing them to clump together with calcium forming a stone
or stones. Below is a list of nutrition interventions that can be instrumental in reducing your risk
of developing this type of stone.
Make sure you are drinking enough fluids. A good rule of thumb is to consume six to eight 8-ounce glasses of water per day.
Avoid eating too much protein as high protein intake will cause the kidneys to excrete more calcium which could lead to stone formation.
Avoid high sodium intake as this also increases the amount of calcium in the urine.
Eat enough dietary calcium. It is recommended to eat calcium with meals so that it will adhere to oxalate in the gut and intestines before it reaches the kidneys. Good sources of calcium include milk, yogurt, and cheese. *Calcium supplements should be discussed with your physician as you want the calcium consumed to be from dietary sources.
Avoid vitamin C supplements as this can cause high amounts of oxalates in the urine.
Limit high oxalate foods such as spinach, nuts, rhubarb, beets, raspberries, wheat bran and chocolate, but do not avoid all oxalate foods. A common misconception is that oxalate foods should be avoided; however, foods highest in oxalate are also rich in fiber, magnesium and potassium and the goal is a well-balanced, healthy diet.
2. Calcium Phosphate stones are less common than calcium oxalate stones and are generally
caused by abnormalities in the way the urinary system functions. They are usually the result of
high pH in the urine, a condition known as renal tubular acidosis. Research has found that many
calcium phosphate stones also contain oxalate, so the above recommendations are also
beneficial for calcium phosphate stones.
3. Uric Acid stones form when the levels of uric acid in the urine are too high, and/or the urine is
too acidic on a regular basis. Inherited problems in how the body processes uric acid or protein
in the diet can increase the acid in urine. There is an increased risk of uric acid stones in people
with gout, diabetes or individuals receiving chemotherapy. Consuming adequate fluids on a daily
basis along with limiting sodium intake and maintaining a healthy weight are key interventions
to help with prevention of these type of stones. Cutting down on high-purine foods such as red
meat, organ meats, beer/alcoholic beverages, meat-based gravies, sardines, anchovies and
shellfish can help to lower the production of uric acid excreted by the kidneys.
4. Struvite stones are less common and are caused by infections in the upper urinary tract. These
stones typically grow very large and the need for surgical intervention to break up the stone is
usually indicated as passing a struvite stone is rare. Adequate hydration is recommended;
however, medication may be needed to prevent future struvite stones.
5. Cystine stones are caused by an inherited disorder called cystinuria and is a lifelong condition
that needs to be actively managed to keep stones from forming. Treatment of these stones
starts with adequate hydration along with reducing sodium intake, eating less meat, and taking
medications prescribed by your physician. These stones may be small enough to pass out of the
body during urination, but larger stones may require surgery.
Kidney stones can be an extremely painful condition and most individuals who have passed a stone ever want to experience it again. By working with your healthcare provider to discover the cause and type of your stone you may be able to make lifestyle changes to prevent recurrence.
Sources:
“Kidney Stones”. National Kidney Foundation. Kidney stones | National Kidney Foundation.
“Kidney Stones”. John Hopkins Medicine. Kidney Stones | Johns Hopkins Medicine.
“Kidney Stones”. Urology Care Foundation. Kidney Stones: Symptoms, Diagnosis & Treatment - Urology Care Foundation (urologyhealth.org).
“Kidney Stones Guide”. Cleveland Clinic. Kidney Stones Guide (clevelandclinic.org).
“Kidney Stones: Tiny and painful, but treatable”. Mayo Clinic Health System. Kidney stones: Tiny, painful, treatable - Mayo Clinic Health System.