Water is the cornerstone of human life. After oxygen, water is what our body needs most. All metabolic processes, organ functions and the balance inside our cells are regulated by water. A person can survive for weeks without food, but only a few days without water.
About 60–70% of an adult’s body is water. This proportion varies with age, sex, weight and physical activity.
- With age, the body’s fat percentage increases, so its water percentage decreases.
- In men, the water percentage is usually higher than in women.
- In lean and active people, the water percentage is higher because there is less fat tissue.
Across the life cycle, the proportion of water is 95% in an embryo, 80% in a baby, 75% in a child, 70% in an adult and about 50% in an elderly person. This difference shows that the body’s capacity to retain water decreases with age.
Why Is Fluid Balance in the Body Important?
A healthy person has no problems as long as they can balance the fluid they take in with the fluid they lose. In people with kidney failure, however, this balance is disturbed. When the kidneys do not work sufficiently, excess water and salt begin to build up in the body. This puts an extra burden on both the organs and the circulatory system. One of the most important goals of dialysis treatment is to remove this excess fluid from the body.
Symptoms of Fluid Overload in the Body
Fluid build-up usually develops slowly, so it is important to notice the early signs.
The following may indicate fluid overload in dialysis patients:
- Rising blood pressure: Excess fluid increases the pressure inside the blood vessels and leads to hypertension.
- Weight gain: Gaining more weight than expected between dialysis sessions is the clearest sign of water build-up in the body.
- Palpitations and shortness of breath: When the heart struggles to pump the increased fluid load, palpitations and rapid breathing occur.
- Swelling (edema) in the legs, hands, abdomen, face and around the eyes: Shoes or rings feeling tight and puffy eyelids in the morning are signs to watch for.
- Shortness of breath when lying down and needing more pillows: When fluid starts to collect in the lungs, the person cannot breathe comfortably lying down.
- Struggling when walking, difficulty climbing stairs: Increased fluid raises the load on the heart and lungs and reduces exercise capacity.
- A throbbing headache starting at the back of the neck: A common result of high blood pressure.
Causes of Fluid Overload
When high blood pressure, weakness, shortness of breath or edema is detected in a dialysis patient, the first cause to consider is fluid overload. The most common causes are:
- Exceeding the daily fluid limit (drinking a lot of water, soup, fruit, tea and coffee)
- High salt intake (salty foods, pickles, ready-made sauces, packaged snacks)
- Dialysis sessions not being attended regularly or insufficient fluid removal
- Insufficient urine output (further decline in kidney function)
Salt is the most important cause of fluid build-up. Salt increases water retention in the body and triggers thirst, so the person drinks more fluid without realizing it.
How Can It Be Controlled?
Maintaining fluid balance is the most basic step in improving the quality of life of dialysis patients:
- Track your weight between dialysis sessions. Ideally, you should not gain more than 1–2 kg between sessions.
- Reduce salt. Don’t add salt to meals and avoid processed foods.
- Plan your fluid intake. Learn your permitted daily amount; use small cups and quench your thirst with ice chips.
- Take foods that contain fluid into account. Soup, fruit, yogurt and ice cream also count towards your fluid intake.
- Develop ways to cope with thirst. Mint gum, rinsing your mouth with cold water and sucking a slice of lemon can help.
- Exercise regularly. Light walks and leg exercises support circulation and help reduce edema.
- Work together with your doctor and dietitian. Fluid and salt balance needs to be adjusted to your personal needs.
