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Kidneys are the organs that help filter waste products from the blood. They are also involved in regulating blood pressure, electrolyte balance, and red blood cell production in the body. Symptoms of kidney failure are due to the build-up of waste products in the body that may cause weakness, shortness of breath, lethargy, and confusion. Inability to remove potassium from the bloodstream may lead to abnormal heart rhythms and sudden death. Initially kidney failure may cause no symptoms. There are numerous causes of kidney failure, and treatment of the underlying disease may be the first step in correcting the kidney abnormality. Some causes of kidney failure are treatable and the kidney function may return to normal. Unfortunately, kidney failure may be progressive in other situations and may be irreversible.
The diagnosis of kidney failure usually is made by blood tests measuring BUN, creatinine, and glomerular filtration rate (GFR).
Treatment of the underlying cause of kidney failure may return kidney function to normal. Lifelong efforts to control blood pressure and diabetes may be the best way to prevent chronic kidney disease and its progression to kidney failure signs. As we age kidney function gradually decreases over time.
If the kidneys fail completely, the only treatment options available.
Kidney in our body
The kidneys play key roles in body function, not only by filtering the blood and getting rid of waste products, but also by balancing the electrolyte levels in the body, controlling blood pressure, and stimulating the production of red blood cells.
The kidneys are located in the abdomen toward the back, normally one on each side of the spine. They get their blood supply through the renal arteries directly from the aorta and send blood back to the heart via the renal veins to the vena cava. (The term "renal" is derived from the Latin name for kidney.)
The kidneys have the ability to monitor the amount of body fluid, the concentrations of electrolytes like sodium and potassium, and the acid-base balance of the body. They filter waste products of body metabolism, like urea from protein metabolism and uric acid from DNA breakdown. Two waste products in the blood usually are measured; 1) blood urea nitrogen (BUN), and 2) creatinine (Cr).
When blood flows to the kidney, sensors within specialized kidney cells regulate how much water to excrete as urine, along with what concentration of electrolytes. For example, if a person is dehydrated from exercise or from an illness, the kidneys will hold onto as much water as possible and the urine becomes very concentrated. When adequate water is present in the body, the urine is much more dilute, and the urine becomes clear. This system is controlled by renin, a hormone produced in the kidney that is part of the fluid and blood pressure regulation systems of the body.
Kidneys are also the source of erythropoietin in the body, a hormone that stimulates the bone marrow to make red blood cells. Special cells in the kidney monitor the oxygen concentration in blood. If oxygen levels fall, erythropoietin levels rise and the body starts to manufacture more red blood cells.
Urine that is made by each kidney flows through the ureter, a tube that connects the kidney to the bladder. Urine is stored within the bladder, and when urination occurs, the bladder empties urine through a tube called the urethra.
Causes of Kidney failure
Kidney failure may occur from an acute situation that injures the kidneys or from chronic diseases that gradually cause the kidneys to stop functioning kidney failure signs.
In acute renal failure, kidney function is lost rapidly and can occur from a variety of insults to the body. Since most people have two kidneys, both kidneys must be damaged for complete kidney failure to occur. Fortunately, if only one kidney fails or is diseased it can be removed, and the remaining kidney may continue to have normal kidney (renal) function. If a both patient's kidneys are injured or diseased, a donor kidney(s) may transplanted.
The list of causes of kidney failure is often categorized based on where the injury has occurred.
Prerenal causes (pre=before + renal=kidney) causes are due to decreased blood supply to the kidney. Examples of prerenal causes of kidney failure are:
- Hypovolemia (low blood volume) due to blood loss
- Dehydration from loss of body fluid (for example, vomiting, diarrhea, sweating, fever)
- Poor intake of fluids
- Medication, for example, diuretics ("water pills") may cause excessive water loss
- Abnormal blood flow to and from the kidney due to obstruction of the renal artery or vein.
Renal causes of kidney failure (damage directly to the kidney itself) include:
Sepsis: The body's immune system is overwhelmed from infection and causes inflammation and shutdown of the kidneys. This usually does not occur with simple urinary tract infections.
Medications: Some medications are toxic to the kidney including:
- Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin, and others), and naproxen (Aleve, Naprosyn)
- Antibiotics like aminoglycosides gentamicin (Garamycin), tobramycin
- lithium (Eskalith, Lithobid)
- Iodine-containing medications such as those injected for radiology dye studies
Rhabdomyolysis: This is a situation in which there is significant muscle breakdown in the body, and the damaged muscle fibers clog the filtering system of the kidneys. Massive muscle injury may occur because of trauma, crush injuries, and burns. Some medications used to treat highcholesterol may causerhabdomyolysis.
Multiple myeloma and kidney failure signs
Acute glomerulonephritis or inflammation of the glomeruli, the filtering system of the kidneys. Many diseases can cause this inflammation including:
- Systemic lupus erythematosus
- Wegener's granulomatosis
- Goodpasture syndrome.
Hemolytic uremic syndrome: This condition results from abnormal destruction of red blood cells. It most often occurs in children after certain infections, but also may be caused by medications, pregnancy, or can occur for unknown reasons.
Post renal causes of kidney failure (post=after + renal= kidney) are due to factors that affect outflow of the urine:
Obstruction of the bladder or the ureters can cause back pressure because the kidneys continue to produce urine, but the obstruction acts like a dam, and urine backs up into the kidneys. When the pressure increases high enough, the kidneys are damaged and shut down.
Prostatic hypertrophy or prostate cancer may block the urethra and prevents the bladder from emptying.
Tumors in the abdomen that surround and obstruct the ureters.
Kidney stones. Usually, kidney stones affect only one kidney and do not cause kidney failure. However, if there is only one kidney present, a kidney stone may cause the remaining kidney to fail.
Chronic renal failure develops over months and years. The most common causes of chronic renal failure are related to:
- poorly controlled diabetes,
- poorly controlled high blood pressure, and
- chronic glomerulonephritis.
Less common causes of chronic renal failure include:
- Polycystic kidney disease
- Reflux nephropathy (damage caused by urine backflow from the bladder into the ureters and kidney)
- Nephrotic syndrome
- Alport's disease
- Interstitial nephritis
- Kidney stones
- Prostate disease.
Initially, kidney failure may be not produce any symptoms (asymptomatic). As kidney function decreases, the symptoms are related to the inability to regulate water and electrolyte balances, clear waste products from the body, and promote red blood cell production.
If unrecognized or untreated, the following symptoms of kidney failure may develop into life-threatening circumstances.
- Lethargy
- Weakness
- Shortness of breath
- Generalized swelling (edema)
- Generalized weakness due to anemia
- Loss of appetite
- Lethargy
- Fatigue
- Congestive heart failure
- Metabolic acidosis
- High blood potassium (hyperkalemia)
- Fatal heart rhythm disturbances (arrhythmias) including ventricular tachycardia and ventricular fibrillation
- Rising urea levels in the blood (uremia) may lead to brain encephalopathy, pericarditis (inflammation of the heart lining), or low calcium blood levels (hypocalcemia).
Kidney failure in itself does not cause pain. However, the consequences of kidney failure may cause pain and discomfort in different parts of the body.
Amyloid proteins
Normal functioning kidneys filter amyloid (a protein) from the blood stream. In kidney failure amyloid proteins in the blood rise, and can separate and clump together forming amyloid deposits into a variety of tissue and organs, including joints and tendons. This can result in symptoms of:
- joint stiffness,
- pain, and
- swelling.
- Patients who are on dialysis may have discomfort when on the dialysis machine.
- Pain is often a consequence of the underlying chronic disease that led to kidney failure, for example:
- People with poorly controlled diabetes may develop diabetic neuropathy pain.
- People who have peripheral vascular disease also may have pain in their extremities, and may develop claudication (leg pain that occurs with walking).
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