Kidney Disease
CHRONIC KIDNEY DISEASE
Chronic Kidney Disease Overview
Normal Kidneys and Their Function
The kidneys are a pair of bean-shaped organs that lie on either side of the spine in the lower middle of the back. Each kidney weighs about ¼ pound and contains approximately one million filtering units called nephrons. Each nephron is made of a glomerulus and a tubule. The glomerulus is a miniature filtering or sieving device while the tubule is a tiny tube like structure attached to the glomerulus.The kidneys are connected to the urinary bladder by tubes called ureters. Urine is stored in the urinary bladder until the bladder is emptied by urinating. The bladder is connected to the outside of the body by another tube like structure called the urethra.
The main function of the kidneys is to remove waste products and excess water from the blood. The kidneys process about 200 liters of blood every day and produce about two liters of urine. The waste products are generated from normal metabolic processes including the breakdown of active tissues, ingested foods, and other substances. The kidneys allow consumption of a variety of foods, drugs, vitamins and supplements, additives, and excess fluids without worry that toxic by-products will build up to harmful levels. The kidney also plays a major role in regulating levels of various minerals such as calcium, sodium, and potassium in the blood.
- As the first step in filtration, blood is delivered into the glomeruli by microscopic leaky blood vessels called capillaries. Here, blood is filtered of waste products and fluid while red blood cells, proteins, and large molecules are retained in the capillaries. In addition to wastes, some useful substances are also filtered out. The filtrate collects in a sac called Bowman's capsule.
- The tubules are the next step in the filtration process. The tubules are lined with highly functional cells which process the filtrate, reabsorbing water and chemicals useful to the body while secreting some additional waste products into the tubule.
- Active form of vitamin D (calcitriol or 1,25 dihydroxy-vitamin D), which regulates absorption of calcium and phosphorus from foods, promoting formation of strong bone.
- Erythropoietin (EPO), which stimulates the bone marrow to produce red blood cells.
- Renin, which regulates blood volume and blood pressure.
Chronic kidney disease
Chronic kidney disease occurs when one suffers from gradual and usually permanent loss of kidney function over time. This happens gradually, usually months to years. Chronic kidney disease is divided into five stages of increasing severity (see Table 1 below). The term "renal" refers to the kidney, so another name for kidney failure is "renal failure." Mild kidney disease is often called renal insufficiency.
With loss of kidney function, there is an accumulation of water; waste; and toxic substances, in the body, that are normally excreted by the kidney. Loss of kidney function also causes other problems such as anemia, high blood pressure, acidosis (excessive acidity of body fluids), disorders of cholesterol and fatty acids, and bone disease.
Stage 5 chronic kidney disease is also referred to as kidney failure, end-stage kidney disease, or end-stage renal disease, wherein there is total or near-total loss of kidney function. There is dangerous accumulation of water, waste, and toxic substances, and most individuals in this stage of kidney disease need dialysis or transplantation to stay alive.
Unlike chronic kidney disease, acute kidney failure develops rapidly, over days or weeks.
- Acute kidney failure usually develops in response to a disorder that directly affects the kidney, its blood supply, or urine flow from it.
- Acute kidney failure is often reversible, with complete recovery of kidney function.
- Some patients are left with residual damage and can have a progressive decline in kidney function in the future.
- Others may develop irreversible kidney failure after an acute injury and remain dialysis-dependent.
Table 1. Stages of Chronic Kidney Disease
| Stage | Description | GFR* mL/min/1.73m2 |
| 1 | Slight kidney damage with normal or increased filtration | More than 90 |
| 2 | Mild decrease in kidney function | 60-89 |
| 3 | Moderate decrease in kidney function | 30-59 |
| 4 | Severe decrease in kidney function | 15-29 |
| 5 | Kidney failure | Less than 15 (or dialysis) |
*GFR is glomerular filtration rate, a measure of the kidney's function.
Chronic Kidney Disease Causes
Although chronic kidney disease sometimes results from primary diseases of the kidneys themselves, the major causes are diabetes and high blood pressure.- Type 1 and type 2 diabetes mellitus cause a condition called diabetic nephropathy, which is the leading cause of kidney disease in the United States.
- High blood pressure (hypertension), if not controlled, can damage the kidneys over time.
- Glomerulonephritis is the inflammation and damage of the filtration system of the kidneys, which can cause kidney failure. Postinfectious conditions and lupus are among the many causes of glomerulonephritis.
- Polycystic kidney disease is an example of a hereditary cause of chronic kidney disease wherein both kidneys have multiple cysts.
- Use of analgesics such as acetaminophen (Tylenol) and ibuprofen (Motrin, Advil) regularly over long durations of time can cause analgesic nephropathy, another cause of kidney disease. Certain other medications can also damage the kidneys.
- Clogging and hardening of the arteries (atherosclerosis) leading to the kidneys causes a condition called ischemic nephropathy, which is another cause of progressive kidney damage.
- Obstruction of the flow of urine by stones, an enlarged prostate, strictures (narrowings), or cancers may also cause kidney disease.
- Other causes of chronic kidney disease include HIV infection, sickle cell disease, heroin abuse, amyloidosis, kidney stones, chronic kidney infections, and certain cancers.
- Diabetes mellitus type 1 or 2
- High blood pressure
- High cholesterol
- Heart disease
- Liver disease
- Amyloidosis
- Sickle cell disease
- Systemic Lupus erythematosus
- Vascular diseases such as arteritis, vasculitis, or fibromuscular dysplasia
- Vesicoureteral reflux (a urinary tract problem in which urine travels the wrong way back toward the kidney)
- Require regular use of anti-inflammatory medications
- A family history of kidney disease
How Common is Chronic Kidney Disease?
- Chronic kidney disease is a growing health problem in the United States. A report by the Centers for Disease Control (CDC) determined that 16.8% of all adults above the age of 20 years have chronic kidney disease. Thus, one in six individuals has kidney disease. By disease stage, the prevalence is as follows:
- stage 1, 3.1%;
- stage 2, 4.1%;
- stage 3, 7.6%;
- stage 4; and
- stage 5, 0.5%.
- stage 1, 3.1%;
- There are over 500,000 persons on dialysis or who have received kidney transplants.
- The prevalence of chronic kidney disease has increased by 16% from the previous decade. The increasing incidence of diabetes mellitus, hypertension (high blood pressure), obesity, and an aging population have contributed to this increase in kidney disease.
- Chronic kidney disease is more prevalent among individuals above 60 years of age (39.4%).
- Kidney disease is more common among Hispanic, African American, Asian or Pacific Islander, and Native American people.
Chronic Kidney Disease Symptoms
The kidneys are remarkable in their ability to compensate for problems in their function. That is why chronic kidney disease may progress without symptoms for a long time until only very minimal kidney function is left.Because the kidneys perform so many functions for the body, kidney disease can affect the body in a large number of different ways. Symptoms vary greatly. Several different body systems may be affected. Notably, most patients have no decrease in urine output even with very advanced chronic kidney disease.
Effects and symptoms of chronic kidney disease include;
- need to urinate frequently, especially at night (nocturia);
- swelling of the legs and puffiness around the eyes (fluid retention);
- high blood pressure;
- fatigue and weakness (from anemia or accumulation of waste products in the body);
- loss of appetite, nausea and vomiting;
- itching, easy bruising, and pale skin (from anemia);
- shortness of breath from fluid accumulation in the lungs;
- headaches, numbness in the feet or hands (peripheral neuropathy), disturbed sleep, altered mental status (encephalopathy from the accumulation of waste products or uremic poisons), and restless legs syndrome;
- chest pain due to pericarditis (inflammation around the heart);
- bleeding (due to poor blood clotting);
- bone pain and fractures; and
- decreased sexual interest and erectile dysfunction.
When to Seek Medical Care
Several signs and symptoms may suggest complications of chronic kidney disease. Call your health care practitioner if you notice any of the following symptoms:- Change in energy level or strength
- Increased water retention (puffiness or swelling) in the legs, around the eyes, or in other parts of the body
- Shortness of breath or change from normal breathing
- Nausea or vomiting
- Lightheadedness
- Severe bone or joint pain
- Easy bruising
- Itching
See your health care practitioner as recommended for monitoring and treatment of chronic conditions such as diabetes, high blood pressure, and high cholesterol.
The following signs and symptoms represent the possibility of a severe complication of chronic kidney disease and warrant a visit to the nearest hospital emergency department.
- Change in level of consciousness - extreme sleepiness or difficult to awaken
- Fainting
- Chest pain
- Difficulty breathing
- Severe nausea and vomiting
- Severe bleeding (from any source)
- Severe weakness
Chronic Kidney Disease Treatment
Self-Care at Home
Chronic kidney disease is a disease that must be managed in close consultation with your health care practitioner. Self-treatment is not appropriate.- There are, however, several important dietary rules you can follow to help slow the progression of your kidney disease and decrease the likelihood of complications.
- This is a complex process and must be individualized, generally with the help of your health care practitioner and a registered dietitian.
The following are general dietary guidelines:
- Protein restriction: Decreasing protein intake may slow the progression of chronic kidney disease. A dietitian can help you determine the appropriate amount of protein for you.
- Salt restriction: Limit to 4-6 grams a day to avoid fluid retention and help control high blood pressure.
- Fluid intake: Excessive water intake does not help prevent kidney disease. In fact, your doctor may recommend restriction of water intake.
- Potassium restriction: This is necessary in advanced kidney disease because the kidneys are unable to remove potassium. High levels of potassium can cause abnormal heart rhythms. Examples of foods high in potassium include bananas, oranges, nuts, and potatoes.
- Phosphorus restriction: Decreasing phosphorus intake is recommended to protect bones. Eggs, beans, cola drinks, and dairy products are examples of foods high in phosphorus.
- carefully follow prescribed regimens to control your blood pressure and/or diabetes;
- stop smoking; and
- lose excess weight.
- Certain analgesics: Aspirin; nonsteroidal antiinflammatory drugs (NSAIDs, such as ibuprofen [Motrin, for example])
- Fleets or phosphosoda enemas because of their high content of phosphorus
- Laxatives and antacids containing magnesium and aluminum such as magnesium hydroxide (Milk of Magnesia) and famotidine (Mylanta)
- Ulcer medication H2-receptor antagonists: cimetidine (Tagamet), ranitidine (Zantac), (decreased dosage with kidney disease)
- Decongestants such as pseudoephedrine (Sudafed) especially if you have high blood pressure
- Alka Seltzer, since this contains large amounts of salt
- Herbal medications
Dialysis For Kidney Disease
Medical Treatment
There is no cure for chronic kidney disease. The four goals of therapy are to:- slow the progression of disease;
- treat underlying causes and contributing factors;
- treat complications of disease; and
- replace lost kidney function.
- Control of blood glucose: Maintaining good control of diabetes is critical. People with diabetes who do not control their blood glucose have a much higher risk of all complications of diabetes, including chronic kidney disease.
- Control of high blood pressure: This also slows progression of chronic kidney disease. It is recommended to keep your blood pressure below 130/80 mm Hg if you have kidney disease. It is often useful to monitor blood pressure at home. Blood pressure medications known as angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB) have special benefit in protecting the kidneys.
- Diet: Diet control is essential to slowing progression of chronic kidney disease and should be done in close consultation with your health care practitioner and a dietitian. For some general guidelines, see the Self-Care at Home section of this article.
- Fluid retention can be treated with any of a number of diuretic medications, which remove excess water from the body. However, these drugs are not suitable for all patients.
- Anemia can be treated with erythropoiesis stimulating agents such as erythropoietin or darbepoetin (Aranesp, Aranesp Albumin Free, Aranesp SureClick). Erythropoiesis stimulating agents are a group of drugs that replace the deficiency of erythropoietin, which is normally produced by healthy kidneys. Often, patients treated with such drugs require iron supplements by mouth or sometimes even intravenously.
- Bone disease develops in kidney disease due to an inability to excrete phosphorus and a failure to form activated Vitamin D. In such circumstances, your physician may prescribe drugs binding phosphorus in the gut, and may prescribe active forms of vitamin D.
- Acidosis may develop with kidney disease. The acidosis may cause breakdown of proteins, inflammation, and bone disease. If the acidosis is significant, your doctor may use drugs such as sodium bicarbonate (baking soda) to correct the problem.
Ten Tips for Taking Control of your Kidney Disease
The more you know and understand about your kidney disease the better you will feel. When you are a dialysis patient it always seems as if someone is telling you what you can and should do. Understanding why the doctors and staff ask you to do these things is important so you can make better choices. In order to do this one needs to take control over their life. There are many ways to take control. Education and learning about dialysis and your treatment is just one way. Taking responsibility for your treatment, diet and mediction is another. Finally the hardest and one of the most important ways to maintain control in your life is by keeping a positive attitude. Following are some tips that dialysis patients can use to gain control over their lives:
1. Dialysis is not the end of the world. You can change your lifestyle, and still enjoy life.
2. Learn everything you can about your disease, dialysis, how the machine works and what the displays on the machine mean.
3. Ask the nurses if you can learn to put yourself on the machine.
4. Question the staff and doctors about things that confuse you, including medications they are giving you on treatment.
5. Learn what foods are bad for you and ask the dietitian for suggestions if you have to give up some favorite foods.
6. Make sure you have a good scale at home and understand the importance of a "dry weight".
7. Know the metric system - most hospitals and dialysis centers use this.
8. Understand how it is important to not miss or cut treatments short.
9. Know your medications and their purpose - don't call them the "yellow pill".
10. Keep a sense of humor and always treat others as you would want to be treated.
1. Dialysis is not the end of the world. You can change your lifestyle, and still enjoy life.
2. Learn everything you can about your disease, dialysis, how the machine works and what the displays on the machine mean.
3. Ask the nurses if you can learn to put yourself on the machine.
4. Question the staff and doctors about things that confuse you, including medications they are giving you on treatment.
5. Learn what foods are bad for you and ask the dietitian for suggestions if you have to give up some favorite foods.
6. Make sure you have a good scale at home and understand the importance of a "dry weight".
7. Know the metric system - most hospitals and dialysis centers use this.
8. Understand how it is important to not miss or cut treatments short.
9. Know your medications and their purpose - don't call them the "yellow pill".
10. Keep a sense of humor and always treat others as you would want to be treated.