Chronic kidney disease (chronic renal failure) is a condition characterized by decreased renal function due to a chronic disorder affecting the kidney.
Chronic kidney disease is a term used to define a decreased renal function with a glomerular filtration rate of fewer than 60 ml/min/1,73m2 for at least 3 months. Impaired kidney function leads to the accumulation of waste products (which are normally excreted in urine) in the body, fluid overload, protein loss, and acid base imbalance – the symptoms and signs of renal failure are collectively known as uremia. Of note, for a long time person remain asymptomatic and may not know about the gradually developing disorder until eventually develops irreversible end-stage renal disease.
- Hypertension-related nephrosclerosis or kidney damage due to another vascular disease;
- Diabetic nephropathy;
- Chronic glomerulonephritis;
- Renal amyloidosis;
- Polycystic kidney disease;
- Medullary cystic disease;
- Renal artery stenosis;
- Tubulointerstitial nephritis due to heavy metals poisoning, drug hypersensitivity, sickle cell disease;
- Collagen-vascular diseases;
- Other chronic diseases affecting the kidneys;
All of the listed factors damage the kidney, whereas the remaining nephrons undergo hypertrophy. The kidney tissues are progressively damaged and connective tissue substitutes the injured cells until the kidney function is severely impaired.
- Small weight at birth;
- Obesity and overweight;
- Diabetes mellitus;
- Autoimmune diseases;
- Family history of kidney disease;
- Acute kidney injury in the past;
- Structural abnormalities of the urinary system;
Stage of the chronic kidney disease is evaluated according to the glomerular filtration rate – the speed of plasma filtration in the kidneys which is the first step of urine production. Special formulas are used to measure GFR according to the serum creatinine levels and a person’s age.
- Stage 1 – GFR normal or high – more than 90 ml/min per 1,73 m2;
- Stage 2 – GFR mildly decreased – 60-89 ml/min per 1,73 m2;
- Stage 3 – GFR moderately to severely decreased – 30-59 ml/min per 1,73 m2;
- Stage 4 – GFR severely decreased – 15-29 ml/min per 1,73 m2;
- Stage 5 – kidney failure with GFR of less than 15 ml/min per 1,73 m2;
Initially, the kidney function is apparent only based on the laboratory studies results which revealed raised urea and creatinine concentrations in blood.
Usually, symptoms of chronic kidney disease develop when renal function is severely impaired and the GFR is below 30 ml/min/1,73 m2, although then almost all of the body systems and organs are involved. Relatively early occurs nocturia – excessive urination at night, which generally mean that a person wakes up several times at night for voiding.
A person usually has pale skin with excoriations due to itching and easy bruising. Other symptoms of the disease include tiredness and fatigue, muscle weakness, headaches, breathlessness, poor appetite, nausea, vomiting, hiccups and a metallic taste in the mouth. Foul breath and unpleasant sweat odor may also be noticed as the urea is excreted through the skin by the sweat and saliva. Lower back pain in the region where the kidneys are located may also develop.
The excessive fluid which accumulates in the body causes swelling or puffiness around the eyes, arms, hands, and feet. In extremely severe cases, fluid leaks into the peritoneal cavity causing ascites (accumulation of the fluid in the abdomen), into the pleural cavity causing hydrothorax (accumulation of the fluid in the cavity around the lungs) or into the pericardium (fluid accumulates around the heart).
Toxic substances in the blood also affect the nervous system – a person is irritable, experiences seizures, muscle cramps, memory loss and inability to concentrate. Confusion and coma may also eventually develop.
Men suffer from erectile dysfunction, in females, menstrual cycle abnormalities may be present.
- Complete blood count: Anemia (low red blood cells count and low hemoglobin concentration) due to deficiency of erythropoietin (a hormone produced by the kidneys) is typical for chronic kidney disease. The white blood cell count may be increased if there are any infections which complicate the kidney failure.
- Urinalysis: Urine often appears bloody with high protein levels (proteinuria).
- Serum urea and creatinine: Urea and creatinine levels are increased as kidney function is reduced.
- Serum albumin: As the proteins are lost with the urine serum albumin levels are significantly decreased.
- Serum sodium, potassium, calcium and phosphates: Potassium levels may drastically increase, whereas the concentration of sodium is decreased. Kidneys convert vitamin D into its active form, calcitriol (vitamin D3) which is involved in the control of serum calcium and phosphate levels. Therefore, in case of kidney failure metabolism of these minerals is also impaired.
Ultrasound examination helps to estimate the structure of the kidneys.
- CT/MRI, kidney biopsy:
CT or MRI, a kidney biopsy may be indicated if the cause of kidney failure is unknown.
The sooner the diagnosis is identified and the sooner treatment is initiated, the better prognosis and the outcomes are, the end-stage kidney disease may be prevented.
Maintenance of low-protein diet (0,58 g/kg/day) is recommended in order to reduce the production of waste products. Salt intake should be restricted as it is known that salt retains water in the body. Fluid intake also has to be controlled, sometimes even reduced.
- Synthetic vitamin D (calcitriol, doxercalciferol) and calcium supplements are recommended to increase calcium absorption
- Erythropoesis-stimulating agent, Epoetin alfa, as well as iron supplements (ferrous sulfate, iron dextran complex) are necessary to increase the number of red blood cells and hemoglobin in the blood and treat anemia.
- Phosphate binders (sevelamer, suroferric oxyhydroxide) are used to decrease serum phosphate levels.
- Antihypertensive drugs such as ACE inhibitors and ARBs help to decrease blood pressure but also are known to slow down the progression of renal failure and reduce proteinuria. Calcium channel blockers, dilthiazem, and verapamil may also be prescribed.
Renal replacement therapy
Renal replacement therapy should be considered when kidney function is severely impaired and medications are not able to relieve the symptoms and maintain homeostasis.
- Peritoneal dialysis;
In the case of end-stage kidney disease, the function of the kidneys is so diminished that the only option is kidney transplantation.