Calcium Oxalate Crystals

Kidney stones can be very painful. They can also cause complications like urinary tract infections. But they are often preventable with a few dietary changes.

Where does oxalate come from?

Oxalate comes from many of the foods in our diet. The main dietary sources of oxalate are:

- French fries and baked potatoes

- spinach and other green, leafy vegetables

- rhubarb

- wheat bran

- almonds

- beets

- navy beans

- chocolate

- okra

- nuts and seeds

- soy products

- tea

- strawberries and raspberries

When you eat these foods, your GI tract breaks them down and absorbs the nutrients. The leftover wastes then travel to your kidneys, which remove them into your urine. The waste from broken-down oxalate is called oxalic acid. It can combine with calcium to form calcium oxalate crystals in the urine.

What are the symptoms?

Kidney stones may not cause symptoms until they start to move through your urinary tract. When stones move, the pain can be intense.

The main symptoms of calcium oxalate crystals in the urine are:

- pain in your side and back that can be intense, and may come in waves
- pain when you urinate
- blood in your urine, which can look red, pink, or brown
- cloudy urine
- foul-smelling urine
- an urgent and constant need to urinate
- nausea and vomiting
- fever and chills if you have an infection

What causes calcium oxalate crystals?

Urine contains chemicals that normally prevent oxalate from sticking together and forming crystals. However, if you have too little urine or too much oxalate, it can crystalize and form stones.

Reasons for this include:

- not drinking enough fluids (being dehydrated)
- eating a diet that’s too high in oxalate, protein, or salt

In other cases, an underlying disease causes the crystals to form into stones. You’re more likely to get calcium oxalate stones if you have:

- hyperparathyroidism, or too much parathyroid hormone
- inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn’s disease
- Dent disease, an inherited disorder that damages the kidneys
- gastric bypass surgery for weight loss
- diabetes
- obesity

Potential treatment options:

Small stones may pass on their own without treatment in about four to six weeks. You can help flush out the stone by drinking extra water.

Your doctor can also prescribe an alpha-blocker. These drugs relax your ureter to help the stone pass from your kidney more quickly.

Pain relievers such as ibuprofen and acetaminophen can help relieve your discomfort until the stone passes. 

However, if you’re pregnant, talk with your healthcare provider before taking non-steroidal, anti-inflammatory drugs (ibuprofen, naproxen, aspirin, and celexcoxib).

If the stone is very large or it doesn’t pass on its own, you may need one of these procedures to remove it:

Extracorporeal shock wave lithotripsy (ESWL):

ESWL delivers sound waves from outside your body to break the stone into little pieces. Within a few weeks after ESWL, you should pass the stone pieces in your urine.

Ureteroscopy: 

In this procedure, your doctor passes a thin scope with a camera on the end through your bladder and into your kidney. Then the stone is either removed in a basket or broken up first with a laser or other tools and then removed. The surgeon may place a thin plastic tube called a stent in the ureter to hold it open and allow urine to drain while you heal.

Percutaneous nephrolithotomy: 

This procedure occurs while you’re asleep and pain-free under general anesthesia. Your surgeon makes a small incision in your back and removes the stone using small instruments.

Possible Prevention:

You can prevent calcium oxalate from forming crystals in your urine and avoid kidney stones by following these tips:

- Drink extra fluids. Some doctors recommend that people who’ve had kidney stones drink 2.6 quarts (2.5 liters) of water each day. Ask your doctor how much fluid is right for you.

- Limit the salt in your diet. A high-sodium diet can increase the amount of calcium in your urine, which can help stones form.

- Watch your protein intake. Protein is essential to a healthy diet, but don’t overdo it. Too much of this nutrient can cause stones to form. Make protein less than 30 percent of your total daily calories.

- Include the right amount of calcium in your diet. Getting too little calcium in your diet can cause oxalate levels to rise. To prevent this, be sure you’re getting the appropriate daily amount of calcium for your age. 

- Cut down on foods that are high in oxalate, like rhubarb, bran, soy, beets, and nuts. When you do eat oxalate-rich foods, have them with something containing calcium, like a glass of milk. This way the oxalate will bind to calcium before it gets to your kidneys, so it won’t crystallize in your urine.

References:

- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1455427/