Kidney disease is a progressive condition that occurs when damage to the kidneys inhibits their function. The kidneys, responsible for filtering waste from the body, do not stop working all at once but slowly lose function over time. There are five stages of kidney disease, based on the glomerular filtration rate (GFR), a measure of kidney function determined by age, race, gender and serum creatinine level. Stage 3, a moderate loss of kidney function, occurs when the GFR is 30 to 59 mililiters per minute, according to DaVita, a dialysis services provider. While some patients will not yet exhibit outward symptoms of disease others will.
Anemia and Fatigue
As kidney function begins to decline, waste products, known as uremic toxins, build up in the blood. In addition, the kidney is responsible for secreting various hormones. One hormone, called erythropoietin (EPO), is necessary to help the bone marrow make new red blood cells. When the kidneys are not able to function properly, they do not release enough EPO, resulting in fewer red blood cells.
A low red blood cell count is a condition called anemia. DaVita reports that anemia often develops during stage 3 kidney disease. Because the red blood cells carry oxygen throughout the body, a decrease in red blood cells reduces the amount of oxygen. With less circulating oxygen, the cells in the body must work harder, which causes fatigue.
Fluid Retention
The kidneys also are responsible for removing excess fluids from the body. As kidney function decreases, excess fluids stay in the body and can settle in the lower legs and hands or around the eyes. This condition is known as edema. If left untreated, edema can cause painful swelling, difficulty walking, increased risk of infection, decreased blood circulation and an increased risk of developing ulcers, according to the doctors at the Mayo Clinic.
High Blood Pressure
Blood pressure is the force of the blood against the blood vessel walls, as described by the National Kidney and Urologic Diseases Information Clearinghouse. There are many factors that can affect blood pressure, and the kidneys play a key role in maintaining a healthy blood pressure. As the kidneys begin to fail, fluids build up in the body, which increases the volume of blood. An increase in blood volume within the blood vessels creates more pressure on the vessel walls, translating to an increase in blood pressure.
This is part of a dangerous cycle, as high blood pressure damages the blood vessel walls. When the blood vessels in the kidney are damaged, it contributes to the kidney damage, causing further loss of function.
