You have kidney stones and your doctor told you that lowering the amount of sodium (or salt) in your diet may help prevent another attack. You heard that
lowering sodium is important for controlling blood pressure, but for kidney stones too?
Calcium and Kidney Stones
Most kidney stones are made up of calcium bound to something else. Calcium is an important mineral in the body. Excess loss of calcium in the urine (called hypercalciuria) is an important risk factor for certain kidney stones.
Sodium Intake and Calcium In the Urine
Eating too much sodium (or salt) can cause your kidneys to lose calcium in the urine. This occurs because sodium and calcium are often lost in the urine by the kidneys together. So, when you eat too much sodium, both sodium and calcium are dumped in the urine.
Sources of Sodium in the Diet
Sodium is a mineral that is found in the body in large amounts. There are many sources of sodium in the diet, but it is particularly common in canned foods, smoked and luncheon meats, condiments, salad dressing and various sauces and seasonings.
Are You Taking In Too Much Sodium?
It isn't always obvious if there is too much sodium in your diet. If you aren't sure, your doctor can order a 24-hour urine collection to find out.
Summary
There are a number of different types of kidney stones that have calcium in them. Excess loss of calcium in the urine can increase the risk for them. Excess intake of sodium can cause an increase in the amount of calcium in the urine. Sodium is found in a great many foods. To know if you have too much sodium in your diet, your doctor can order a 24-hour urine collection to check.
Source
Alan Wasserstein. “Nephrolitiasis”. Primer on Kidney Diseases. San Diego: Academic Press, 1994. 229-233.
