Chronic kidney disease
Kidney failure - chronic; Renal failure - chronic; Chronic renal insufficiency; Chronic kidney failure; Chronic renal failure
Chronic kidney disease is the slow loss of kidney function over time. The main job of the kidneys is to remove wastes and excess water from the body.
The urinary system has four main components: the kidneys, ureters, urinary bladder, and urethra. Urine, a liquid waste product, is formed in the kidneys. From there it moves through the ureters and into the bladder, where it is stored. When the bladder gets full, urine is emptied from the body through the urethra in a process called urination. The creation of urine is far more complex than you might think. The kidneys filter waste from the blood that passes through them, and reabsorb substances that the body requires, even though those requirements may change from moment to moment. The outer portion of each of the kidneys is the cortex, while the inner portion is called the medulla. Each of the kidneys is composed of approximately one million subunits called nephrons. Each nephron consists of a microscopic ball of blood vessels called a glomerulus, which is connected to a twisting length of tube called the renal tubule. Because the blood vessels in the glomeruli are porous, they act as filters, removing most of the water, salt, and waste from the blood that passes through them. As filters, the glomeruli have physical properties that prevent large cells, like red blood cells, from passing into the renal tubules. On the other hand, smaller particles, like sugar and salt, can pass easily through the glomerulus. It is in the renal tubule that waste products are passed into the urine. Substances the body needs, like water and salt, are reabsorbed back into the bloodstream at the same time. The path of urine formation, reabsorption, and excretion begins at the glomerulus, continues through the renal tubules, and proceeds to the ureter. For the most part, urine moves from the outer cortex of the kidneys to the inner medullary region. Urine then proceeds down the ureters and into the bladder. Here you can see a cut-section of the bladder. The unique, expandable cells in the wall of the bladder stretch and become thinner as it fills. Finally, urine is excreted through the urethra.
The kidneys are responsible for removing wastes from the body, regulating electrolyte balance and blood pressure, and the stimulation of red blood cell production.
This is the typical appearance of the blood vessels (vasculature) and urine flow pattern in the kidney. The blood vessels are shown in red and the urine flow pattern in yellow.
The kidneys remove excess fluid and waste from your body. Blood is filtered in the kidneys through nephrons. Each nephron contains a network of small blood vessels, called glomerulus, which are enclosed in a sac called Bowman's capsule. The filtered waste product (urine) flows through tiny tubes and is then passed from the kidneys to the bladder through bigger tubes called ureters.
Causes
Chronic kidney disease (CKD) slowly gets worse over months or years. You may not notice any symptoms for some time. The loss of function may be so slow that you do not have symptoms until your kidneys have almost stopped working.
The final stage of CKD is called end-stage renal disease (ESRD). At this stage, the kidneys are no longer able to remove enough wastes and excess fluids from the body. At this point, you would need dialysis or a kidney transplant.
Diabetes and high blood pressure are the 2 most common causes and account for most cases.
Many other diseases and conditions can damage the kidneys, including:
- Autoimmune disorders (such as systemic lupus erythematosus and scleroderma)
- Birth defects of the kidneys (such as polycystic kidney disease)
- Some toxic chemicals
- Injury to the kidney
- Kidney stones and infection
- Problems with the arteries feeding the kidneys
- Some medicines, such as antibiotics, and pain and cancer medicines
- Backward flow of urine into the kidneys (reflux nephropathy)
CKD leads to a buildup of fluid and waste products in the body. This condition affects most body systems and functions, including:
- High blood pressure
- Low blood cell count
- Vitamin D and bone health
Symptoms
The early symptoms of CKD are the same as for many other illnesses. These symptoms may be the only sign of a problem in the early stages.
Symptoms may include:
- Appetite loss
- General ill feeling and fatigue
- Headaches
- Itching (pruritus) and dry skin
- Nausea
- Weight loss without trying to lose weight
Symptoms that may occur when kidney function has gotten worse include:
- Abnormally dark or light skin
- Bone pain
- Drowsiness or problems concentrating or thinking
- Numbness in the hands and feet
- Muscle twitching or cramps
- Breath odor
- Easy bruising, or blood in the stool
- Excessive thirst
- Frequent hiccups
- Problems with sexual function
- Menstrual periods stop (amenorrhea)
- Shortness of breath
- Sleep problems
- Swelling in the hands and feet
- Vomiting
Exams and Tests
Most people will have high blood pressure at all stages of CKD. During an exam, your health care provider may also hear abnormal heart or lung sounds in your chest. You may have signs of nerve damage during a nervous system exam.
A urinalysis may show protein or other changes in your urine. These changes may appear months to years before symptoms appear.
Tests that check how well the kidneys are working include:
- Creatinine clearance
- Creatinine levels
- Blood urea nitrogen (BUN)
CKD changes the results of several other tests. You may need to have the following blood tests as often as every 2 to 3 months when kidney disease gets worse:
Other tests that may be done to look for the cause or type of kidney disease include:
- CT scan of the abdomen
- MRI of the abdomen
- Ultrasound of the abdomen
- Kidney biopsy
- Kidney scan
- Kidney ultrasound
- Urine protein
This disease may also change the results of the following tests:
- Erythropoietin
- Parathyroid hormone (PTH)
- Bone density test
- Vitamin D level
Treatment
Blood pressure control will slow further kidney damage.
- Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) are used most often.
- The goal is to keep blood pressure at or below 130/80 mm Hg.
Making lifestyle changes can help protect the kidneys, and prevent heart disease and stroke, such as:
- DO NOT smoke.
- Eat meals that are low in fat and cholesterol.
- Get regular exercise (talk to your provider or nurse before starting to exercise).
- Take medicines to lower your cholesterol, if needed.
- Keep your blood sugar under control.
- Avoid eating too much salt or potassium.
Always talk to your provider before taking any over-the-counter medicine. This includes vitamins, herbs and supplements. Make sure all of the providers you visit know you have CKD. Other treatments may include:
- Medicines called phosphate binders, to help prevent high phosphorous levels
- Extra iron in the diet, iron pills, iron given through a vein (intravenous iron) special shots of a medicine called erythropoietin, and blood transfusions to treat anemia
- Extra calcium and vitamin D (always talk to your provider before taking)
Your provider may have you follow a special diet for CKD.
- Limiting fluids
- Eating less protein
- Restricting phosphorous and other electrolytes
- Getting enough calories to prevent weight loss
All people with CKD should be up-to-date on the following vaccinations:
- Hepatitis A vaccine
- Hepatitis B vaccine
- Flu vaccine
- Pneumococcal vaccine (also called "pneumonia vaccine")
- COVID-19
Support Groups
More information and support for people with CKD and their families can be found at a kidney disease support group.
Outlook (Prognosis)
Many people are not diagnosed with CKD until they have lost most of their kidney function.
There is no cure for CKD. Whether it worsens to ESRD, and how quickly, depends on:
- The cause of kidney damage
- How well you take care of yourself
Kidney failure is the last stage of CKD. This is when your kidneys can no longer support our body's needs.
Your provider will discuss dialysis with you before you need it. Dialysis removes waste from your blood when your kidneys can no longer do their job.
In most cases, you will go to dialysis when you have only 10 to 15% of your kidney function left.
Even people who are waiting for a kidney transplant may need dialysis while waiting.
Possible Complications
Complications may include:
- Anemia
- Bleeding from the stomach or intestines
- Bone, joint, and muscle pain
- Changes in blood sugar
- Damage to nerves of the legs and arms (peripheral neuropathy)
- Dementia
- Fluid buildup around the lungs (pleural effusion)
- Heart and blood vessel complications
- High blood phosphorous levels
- High blood potassium levels
- Hyperparathyroidism
- Increased risk of infections
- Liver damage or failure
- Malnutrition
- Miscarriages and infertility
- Seizures
- Swelling (edema)
- Weakening of the bones and increased risk of fractures
Prevention
Treating the condition that is causing the problem may help prevent or delay CKD. People who have diabetes should control their blood sugar and blood pressure levels and should not smoke.
References
Christov M, Sprague SM. Chronic kidney disease - mineral bone disorder. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 53.
Grams ME, McDonald SP. Epidemiology of chronic kidney disease and dialysis. In: Johnson RJ, Floege J, Tonelli M, eds. Comprehensive Clinical Nephrology. 7th ed. Philadelphia, PA: Elsevier; 2024:chap 80.
Levey AS, Sarnak MJ. Chronic kidney disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 116.
Taal MW. Classification and management of chronic kidney disease. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 59.
Version Info
Last reviewed on: 8/28/2023
Reviewed by: Walead Latif, MD, Nephrologist and Clinical Associate Professor, Rutgers Medical School, Newark, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
