Chronic kidney disease (CKD) is common not only in the United States, but also around the world in both developed and developing countries. An estimated 37 million American adults (15 percent of the adult U.S. population) have CKD as defined by the Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease: Improving Global Outcomes (KDIGO) guidelines—an abnormal estimating glomerular filtration rate (eGFR) and/or urine albumin loss (albuminuria) for at least three months.1-4 The leading cause of CKD in the U.S. is diabetes mellitus (DM), but other risk factors for CKD include hypertension, cardiovascular disease, a family history of CKD, and advanced age (>60 years).2
The Centers for Disease Control and Prevention (CDC) recommends kidney disease screening for all people at risk for CKD. Kidney disease screening includes a simple blood test (serum creatinine) and a urinalysis to assess the presence of blood or protein in the urine. The serum creatinine is used to calculate the estimated glomerular filtration rate (eGFR), which is an estimate of kidney function indicating how well the kidneys are cleaning the blood. People with advanced kidney disease can make a normal volume of urine, so daily urine volume is not an indicator of CKD. Anyone with an abnormal CKD screening test needs repeat testing to confirm the abnormal findings over time.
There are many causes of CKD. Diabetes mellitus, hypertension, and cardiovascular disease are systemic diseases that impact kidney function by damaging the large and small blood vessels that are critical to normal kidney function. Some autoimmune diseases, such as systemic lupus erythematosus (SLE), can cause chronic inflammation and kidney damage in the same way inflammation affects other body organs. Glomerular diseases such as focal segmental glomerular sclerosis (FSGS) and IgA nephropathy only affect the kidneys and can cause kidney failure. Inherited diseases such as polycystic kidney disease (PKD) and Fabry's disease as well as congenital kidney abnormalities are also well-known causes of CKD. The evaluation of abnormal kidney function may include renal ultrasound, CT, or MRI to look at the anatomical structure of the kidneys. A renal biopsy may be done to examine the filtering units of the kidney under the microscope.
Measures of kidney function based on the eGFR and the presence of protein in the urine are used to determine kidney disease stage.4 A minor decrease in eGFR with no or little urine protein is consistent with CKD stage 1 as shown in the chart below. CKD stages 2 and 3 represent more significant kidney injury and dysfunction. CKD stages 4 and 5 are considered late-stage CKD consistent with severe kidney damage. People with late-stage CKD often have symptoms of renal failure and should receive nephrology care if they have not been referred to nephrology earlier in CKD care.
CKD stage 1
eGFR ≥ 90 with urine protein
CKD stage 2
eGFR 60–89 with or without urine protein
CKD stage 3a
eGFR 45–59 with or without urine protein
CKD stage 3b
eGFR 30–44 with or without urine protein
CKD stage 4
eGFR 15–29 with or without urine protein
CKD stage 5
eGFR <15 with or without urine protein
CKD staging helps people and care providers estimate the severity of kidney disease and begin treatments to slow CKD progression. CKD is a silent disease without symptoms until very late in the disease course, which is often too late to start treatments that improve patient outcomes and slow CKD progression, so measuring kidney function is critical. Protecting the kidneys includes healthy lifestyle habits such as eating a well-balanced diet low in saturated fats and salt, maintaining an ideal body weight, and exercising regularly.2 Smoking and exposure to secondhand smoke in the home or workplace are associated with the development of CKD and with CKD progression.5,6 If you have CKD, it is important to avoid some over-the-counter medications such as nonsteroidal anti-inflammatory drugs that can worsen kidney function.2 The Medical Education Institute also has some good information about slowing kidney disease.
Research data suggests that some medications slow CKD progression and may prevent patients with CKD from advancing to end stage renal disease (ESRD). Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin-receptor blockers (ARBs) are commonly used, if tolerated, to provide kidney protection from CKD progression.7 Recent research suggests that the SGLT-2 inhibitor canagliflozin—used to treat type 2 DM—may decrease CKD progression and provide some cardiac protection.
Typically, patients do not have symptoms related to CKD until the eGFR falls below 30 ml/min/1.73 m2—consistent with CKD stage 4. Late-stage CKD symptoms include:
Blood measurements of calcium, phosphorus, bicarbonate, and potassium are also abnormal in late-stage CKD and may require treatment intervention.2
People with advanced CKD (typically eGFR <20 ml/min/1.73 m2) should be partnered with a multidisciplinary nephrology team including a nephrologist to consider treatment options. Treatment with a kidney transplant from either a deceased or living donor involves surgical placement of a functioning kidney into a patient with end stage kidney disease (ESKD) or ESRD. A successfully transplanted kidney cleans the blood, effectively restoring adequate kidney function to make people feel well. Kidney transplant is a very effective treatment option that restores excellent quality of life to advanced CKD patients, but it is not a cure for kidney disease. Transplant recipients remain on immunosuppressive therapy that increases infection risk and has medication side effects.
If a kidney transplant is not an immediate possibility for an ESRD patient, dialysis treatment options will be considered. Home dialysis therapies, which provide patient empowerment, choice, and flexibility, should be considered as a first dialysis treatment option.8-10 Starting dialysis with peritoneal dialysis (PD) may be associated with preservation of residual renal function and improvement in early dialysis outcomes.8 While home dialysis options should be considered for every new dialysis patient, some patients will start with in-center hemodialysis (ICHD) as a treatment for ESRD. Treatment choices should be made in collaboration with a nephrologist and the multidisciplinary nephrology team. Some patients, particularly those with advanced age or significant comorbid conditions, may opt for supportive or conservative treatment for advanced CKD that does not include a kidney transplant or dialysis therapy.
Treatment options for ESRD include:
Healthy lifestyle choices are important in preventing the onset of CKD and slowing CKD progression. People with DM can also decrease the risk of CKD by using lifestyle and medications to optimize blood glucose control.2 For people with CKD, managing high blood pressure to achieve a goal of <130/80 mm Hg is recommended to improve outcomes.13 Daily exercise and healthy eating decrease the risk of cardiovascular disease, which is a common cause and complication of CKD.14 The nephrology care team is a key resource for medical interventions that can protect your kidneys.