Types of Kidney stones – Part 1 – Calcium Oxalate Stones
Calcium Oxalate Stones, the most common type of Kidney stones are formed due to excess Calcium or Oxalate or Uric acid along with low citrates. Kidneys clean the blood by filtering waste products such as salts and fluids or liquids and pass them as urine. When the liquid content in the blood is less, typically because the person consumes less than required liquids (water, juice or any other form of liquids), the salts get more concentrated and they start forming small crystals in the kidneys. As more salts get accumulated; the size of these crystals increases, resulting in kidney stone formation. As long as they are small and can be passed out, having more water can be very helpful. But, when they are too big to pass through the ureter, they cause severe pain in the lower back (on the sides) and when passing the urine.

Oxalate is a natural substance that body absorbs from the foods a person eats. Eating foods that have too much of oxalate and drinking less fluids or water, results in formation of Calcium Oxalate Stones. Such foods include black tea, chocolate, nuts, potatoes spinach etc. In Indian traditional cooking, it is not advisable to cook spinach and tomato together as it can result in formation of kidney stones.
What else causes the formation of Calcium Oxalate Stones:
- Not drinking enough fluids is one major reason for formation of kidney stones.
- Consuming diet very high in proteins, calcium, oxalates, sodium and sugars (mostly processed sugar syrups, corn syrups etc)
- Being overweight and obese can also help in formation of kidney stones.
- Medical conditions like – Hyper-parathyroidsm or other genetic conditions like Dent Diasease.
- Ulcerative Colitis, Crohn’s Disease, Gastric bypass surgeries can also result in formation of Kidney stones.
People suffering from Inflammatory Bowel Disease (IBD) (inflammation of all parts or few parts of the digestive system) will most commonly have kidney stones. IBD prevents body from absorbing fats. The un-absorbed fats bind with calcium and leave oxalate behind. This oxalate when being removed by the kidney gets stuck and starts forming crystals. Similarly in people who underwent gastric bypass surgery, will have reduced capacity of absorbing calcium. The un-absorbed calcium gets built up in the kidneys forming kidney stones.
How to avoid formation of calcium oxalate stones?
- Drink plenty of water or other fluids – The major reason for formation of kidney stones is when kidneys doesn’t get enough water to remove solid wastes. You need drink 3 to 4 litres of water every day apart from what you get from your regular food.
- Avoid too much protein – The source of protein can be by eating more meat or taking supplements. Excess protein when not synthesized by the body will be expelled. Kidney stones form because of the excess protein, when it gets stuck in the kidneys.
- Eat less salt and processed sugars – Diet high in sodium or consumption of sugar syrups or drinks high in fructose can lead to stone formation.
- Include good amounts of calcium – General misconception is that, eating calcium rich foods is bad for your health and results in formation of kidney stones. But in fact, opposite is true. Eating calcium rich diet will result in binding of calcium with oxalate in stomach and intestines before it goes to the kidneys. This prevents in forming calcium oxalate stones inside the kidneys. Here, we are referring to eat calcium rich foods but not calcium supplements.
- Avoid vitamin C Supplements.
- Eat foods less in Oxalate. (Peanuts, Spinach, chocolate, nuts, sweet potatoes etc). This doesn’t mean, you need to completely cut down on such foods. You need to reduce the quantity that you take in.
If you ever have pain in your lower back (especially on the sides), have a fever or feel nauseated or vomit, you must contact a good urologist near you for immediate check up. Please don’t self medicate or use pain killers.