Chronic Kidney Failure
Chronic kidney failure is quite common in many patients treated by internal physicians. The kidneys are relatively sensitive organs, they can be easily damaged and once diseased kidneys may slowly deteriorate. Due to the fact that kidneys belong among the most important organs in the body (excretion of waste products, fluid metabolism, blood pressure control, homeostasis, etc.), the consequences of their impaired functions are complex and serious.
Note: If you are interested in acute kidney failure, read the related article.
There are many possible causes of chronic kidney deterioration. The age is certainly a major factor and the kidney functions are naturally reduced in the elderly. Some chronic diseases such as diabetes and hypertension clearly cause an impairment of kidney functions. Especially the diabetes has strong negative effects on kidneys and causes so-called diabetic nephropathy. Kidney impairment is also present due to atherosclerosis leading to narrowing of kidney arteries. Other possible causative factors include the polycystic kidney disease and some forms of chronic glomerulonephritides. The polycystic kidney disease is related to formation of multiple cysts in the kidney tissue and the glomerulonephritides are group of immune-related kidney diseases.
The symptoms of chronic kidney failure result from the functions of healthy kidneys in the organism.
Accumulation of waste products
Impaired renal functions lead to decreased removal of waste products from the body and their concentration in blood rises. There are especially two substances important for the physicians – the urea and creatinine. We check their serum concentration to evaluate the severity of kidney impairment. The increased concentration of nitrogen waste products is known as uremia. The waste products are harmful to brain, it gets damaged and this manifests with various neurologic and psychiatric symptoms (confusion, headaches, psychological, loss of appetite, impaired consciousness, coma and death).
Disruption of internal environment
Chronic kidney failure leads to changes in serum concentration of various minerals. The patient is threatened mainly by accumulation of potassium (hyperkalemia). Increased phosphate level (hyperphosphatemia) is also unpleasant as it decreases the level of blood calcium and triggers bone demineralization (renal osteodystrophy – see below).
Diseased kidneys are less able to remove the fluid out of the body and fail to regulate blood pressure. This leads to uncontrolled hypertension. High blood pressure and excessive amount of fluid in the blood vessels overload the heart and may be followed by a heart failure. The high pressure naturally further damages the kidney and the vicious circle continues.
Chronic renal failure leads to decalcification of the bones and the disease known as renal osteodystrophy. This situation is related to impaired excretion of phosphates. Accumulating phosphates decrease serum level of calcium (the product of phosphate and calcium concentrations is constant). Additionally, diseased kidneys fail to produce vitamin D leading to decreased absorption of calcium in the guts, which aggravates the calcium deficiency. The organism reacts by increased activity of parathyroid hormone (secondary hyperparathyroidism), which causes decalcification of bones and increase of the serum level of calcium. The decalcified bones are fragile and tend to break and to deform. In addition, the patient suffers from an unpleasant bone pain.
Anemia frequently accompanies chronic kidney diseases. This is due to the fact that healthy kidney produce a substance known as erythropoietin (EPO), which is important for the development of red blood cells.
It is important to perform at least basic kidney examination. The kidney functions can be evaluated from renal parameters, i.e. serum levels of certain substances such as urea or creatinine, whose concentrations rise in kidney failure. The kidney function can be calculated from the glomerular filtration, which says how much liquid the kidneys filter per a period of time. The calculation can be done from a sample of urine collected for 24 hours that is sent to a laboratory for examination.
The diagnosis of impaired renal functions should be followed with examination by an imaging method such as the abdominal ultrasound to exclude any organic damage to kidneys or hydronephrosis. In addition, the kidney tissue is usually visibly thinned.
It is essential to treat the underlying cause, if possible. The patient should have adequate fluid intake and slightly reduce the intake of proteins (proteins are decomposed to the nitrogenous waste products). Hypertension should be treated by antihypertensive medications, in ideal case by the ACE-inhibitors that protect the kidney tissue. Bone problems may be solved by administration of calcium, vitamin D and special drugs reducing the serum level of phosphates. Anemia is treated by the erythropoietin.
The last stages of the chronic kidney failure need the chronic dialysis program, which is either lifelong or it is ended by a successful kidney transplantation. Both methods have numerous risks, but without them, the death is inevitable.