Urinary Calcium & Sodium

Calcium and sodium are important minerals in the human body. They interact in a number of ways, and both are involved in muscle and nerve function, as well as other processes in the body. Sodium, in the form of sodium chloride, can increase the amount of calcium excreted in the urine.

Calcium

Most of the body's calcium is in the bones and teeth, while the remaining amount is in the blood and soft tissue. Calcium levels in the body must be maintained within a very narrow range for the body to function normally; this mineral is so critical to normal function that if calcium levels in the blood drop too low, the body will dissolve calcium out of the bones to help restore equilibrium. Excess calcium is excreted in the urine.

Sodium

Sodium chloride, or salt, is essential for life. Although minimal amounts of sodium are needed by the body, multiple mechanisms work to maintain tight regulation over the body concentrations of sodium and chloride. Both minerals are electrolytes that help to manage nerve impulse transmission, muscle contractions and cardiac function. Sodium is also necessary for blood pressure regulation, maintaining blood volume and to help in the absorption of nutrients in the small intestine.

Research

The 1991 "International Journal for Vitamin and Nutrition Research" reported a study of healthy Japanese elders in which calcium and sodium excretion were linked. As sodium intake and sodium excretion rose, calcium excretion also rose. Calcium and sodium excretion in the urine increases at menopause, as does the risk of osteoporosis. Another study published in the June 1993 "Journal of Nutrition" found that postmenopausal women had more calcium than sodium in their urine than premenopausal women.

High Sodium Intake

According to the Linus Pauling Institute, a high sodium intake causes increased loss of calcium in the urine. Because urine is the largest source of calcium loss for humans, dietary sodium has the potential to influence bone loss and contribute to osteoporosis. However, Robert P. Heaney, M.D. notes in the June 2006 "Journal of the American College of Nutrition" that if your calcium intake is adequate, a high sodium intake will not cause any negative health effects.

Further Considerations

Calcium is available in both dietary and supplement form, as is sodium chloride. The Linus Pauling Institute says that sodium intake of 3.8 g per day is the highest recommended intake; it is lower for most people, depending on age and gender. Most people in the United States have higher intakes than the recommended amount. Calcium intake recommendations range from 200 mg per day for infants, to 1300 mg per day for breastfeeding women. If you have questions or concerns about the need for calcium supplementation, discuss them with a health care professional.