When kidneys no longer function adequately, they cannot effectively remove waste products and excess fluid from the blood. This condition, known as kidney failure, necessitates dialysis, a life-sustaining treatment. Dialysis takes over some functions of healthy kidneys, filtering the blood and managing the body’s internal balance. This treatment is important for individuals whose kidney function has significantly declined, typically when only 10-15% of normal function remains. It prevents the buildup of harmful substances and fluid, which can lead to severe health complications.
Sodium’s Role in Health and Kidney Disease
Sodium is a mineral that plays several roles in the human body. It helps regulate fluid balance, influencing blood pressure and blood volume. Sodium is also involved in transmitting nerve impulses and facilitating muscle contractions. Healthy kidneys continually adjust the amount of sodium excreted to maintain a consistent level.
However, impaired kidney function disrupts this balance. Failing kidneys lose their ability to excrete excess sodium, leading to its accumulation. This sodium retention causes the body to hold onto more water, resulting in increased fluid volume. Therefore, managing sodium intake is an important aspect of care for people with kidney disease to prevent adverse effects.
How Dialysis Removes Sodium
Dialysis removes sodium from the body, compensating for the kidneys’ diminished capacity. This process relies on two mechanisms: diffusion and ultrafiltration. Diffusion involves the movement of solutes, like sodium, from an area of higher concentration to an area of lower concentration across a semipermeable membrane. During dialysis, the patient’s blood, containing excess sodium, flows past a dialysis solution (dialysate) with a lower sodium concentration. This concentration gradient drives sodium out of the blood and into the dialysate, where it is removed.
Ultrafiltration, the second mechanism, removes excess fluid along with dissolved sodium. This process uses pressure gradients to pull fluid from the blood across the semipermeable membrane. In hemodialysis, a machine creates negative pressure on the dialysate side, drawing excess water and its dissolved contents, including sodium, from the patient’s blood. For peritoneal dialysis, a sugar-based solution within the abdominal cavity creates an osmotic pull, drawing fluid and sodium from the blood vessels lining the peritoneum.
Health Consequences of High Sodium
When sodium is not removed from the body, it can lead to various health problems. Fluid overload, where excess fluid accumulates in the body’s tissues, is a common consequence. This manifests as swelling in the legs, ankles, hands, and face. Rapid weight gain often signals significant fluid retention.
Increased fluid volume also contributes to high blood pressure, which places additional strain on the cardiovascular system. This sustained pressure can lead to an enlarged and weakened heart, potentially resulting in heart failure. Fluid accumulation in the lungs can cause shortness of breath and difficulty breathing, especially when lying down. Patients might also experience increased thirst and muscle cramps due to electrolyte imbalances associated with high sodium levels.
Managing Sodium Beyond Dialysis
While dialysis plays a primary role in removing excess sodium, dietary management is also important for patients with kidney disease. Limiting sodium intake helps reduce the burden on dialysis and minimize fluid accumulation between treatments. Healthcare teams, including nephrologists and dietitians, guide patients on appropriate sodium restrictions, often ranging from 1,500 to 2,000 milligrams per day. This is considerably lower than average sodium consumption in the general population.
Patients should read food labels carefully, looking for terms like “low sodium” or “sodium-free.” Avoiding highly processed foods, canned goods, and many restaurant meals is important, as these are often significant sources of hidden sodium. Preparing meals at home using fresh ingredients and flavoring food with herbs, spices, and salt-free seasonings can help manage sodium intake effectively. This proactive approach complements dialysis by helping maintain fluid balance and overall well-being.