Chronic Kidney Disease (CKD)
A progressive condition affecting kidney function and the body's ability to filter waste
Table of Contents
Overview
Chronic kidney disease (CKD) is a condition characterized by gradual loss of kidney function over time. Your kidneys filter wastes and excess fluids from your blood, which are then excreted in your urine. When chronic kidney disease reaches an advanced stage, dangerous levels of fluid, electrolytes, and wastes can build up in your body.
CKD affects more than 37 million adults in the United States, with many unaware they have the condition. The disease progresses slowly, and symptoms may not appear until kidney function is significantly impaired. Early detection and treatment can slow or prevent the progression of kidney disease.
The kidneys perform vital functions including filtering waste products, balancing body fluids, regulating blood pressure, producing red blood cells, and activating vitamin D. When kidney function declines, these processes are disrupted, affecting overall health. CKD is classified into five stages based on kidney function, with stage 5 being kidney failure requiring dialysis or transplantation.
Stages of CKD
CKD is classified into five stages based on glomerular filtration rate (GFR), which measures how well kidneys filter blood:
Stage 1: Kidney Damage with Normal Function
- GFR: 90 or above
- Kidney damage present but normal filtering
- Usually no symptoms
- Protein or blood in urine may be detected
Stage 2: Mild Loss of Kidney Function
- GFR: 60-89
- Mild decrease in kidney function
- Usually no symptoms
- Focus on slowing progression
Stage 3: Moderate Loss of Kidney Function
- GFR: 30-59 (divided into 3a: 45-59 and 3b: 30-44)
- More noticeable decrease in function
- Symptoms may begin appearing
- Complications like anemia may develop
Stage 4: Severe Loss of Kidney Function
- GFR: 15-29
- Severe reduction in kidney function
- Multiple symptoms present
- Preparation for dialysis or transplant
Stage 5: Kidney Failure (End-Stage Renal Disease)
- GFR: Less than 15
- Kidneys have lost nearly all function
- Dialysis or transplant required
- Life-threatening without treatment
Symptoms
CKD symptoms often don't appear until kidney function is significantly reduced. Early stages may have no symptoms, making regular screening important for at-risk individuals:
Common Symptoms
Early Stage Symptoms
- High blood pressure
- Changes in urination frequency
- Blood in urine (hematuria)
- Foamy urine (proteinuria)
- Mild fatigue
Advanced Stage Symptoms
- Severe fatigue and weakness: Due to anemia and toxin buildup
- Swelling: In feet, ankles, hands, and face
- Difficulty breathing: From fluid buildup in lungs
- Nausea and vomiting: From waste accumulation
- Loss of appetite: Leading to weight loss
- Metallic taste: In mouth
- Itching: From toxin buildup in blood
- Muscle cramps: Especially at night
- Sleep problems: Including restless legs
- Cognitive issues: Difficulty concentrating, confusion
- Chest pain: If fluid builds around heart
- Bone pain: From mineral imbalances
Urinary Changes
- Increased frequency, especially at night
- Decreased urine output in advanced stages
- Difficulty urinating
- Pressure when urinating
- Dark, tea-colored urine
Causes and Risk Factors
CKD occurs when diseases or conditions damage the kidneys and decrease their ability to function:
Primary Causes
- Diabetes: Leading cause, accounting for about 44% of cases
- High blood pressure: Second leading cause, about 28% of cases
- Glomerulonephritis: Inflammation of kidney's filtering units
- Polycystic kidney disease: Inherited disorder causing cysts
- Recurrent kidney infections: Pyelonephritis
- Prolonged obstruction: From kidney stones, enlarged prostate
- Vesicoureteral reflux: Urine backs up into kidneys
Risk Factors
Medical Conditions
- Cardiovascular disease
- Obesity
- High cholesterol
- Lupus and other autoimmune diseases
- Sleep apnea
- Chronic urinary tract infections
Demographics
- Age: Risk increases with age, especially after 60
- Family history: Genetic predisposition
- Race/ethnicity: Higher risk in African Americans, Hispanics, Native Americans
- Gender: Slightly more common in women
Lifestyle Factors
- Smoking
- Heavy use of pain medications (NSAIDs)
- Exposure to certain toxins
- Low birth weight
Diagnosis
Early detection of CKD is crucial for slowing progression. Diagnosis involves various tests to assess kidney function and damage:
Blood Tests
Serum Creatinine and eGFR
Creatinine is a waste product filtered by kidneys. Elevated levels indicate reduced kidney function. eGFR (estimated glomerular filtration rate) is calculated from creatinine levels and is the best overall indicator of kidney function.
Blood Urea Nitrogen (BUN)
Measures waste product levels. Elevated BUN suggests reduced kidney function but can be affected by other factors.
Complete Blood Count
Checks for anemia, common in CKD due to reduced erythropoietin production.
Urine Tests
Urinalysis
Detects abnormalities like protein, blood, or white blood cells in urine.
Albumin-to-Creatinine Ratio
Measures protein in urine. Persistent protein in urine (proteinuria) indicates kidney damage.
24-Hour Urine Collection
Measures total protein excretion and creatinine clearance for accurate kidney function assessment.
Imaging Tests
- Ultrasound: Shows kidney size, structure, and obstruction
- CT scan: Detailed images of kidneys and urinary tract
- MRI: For detailed soft tissue imaging
Kidney Biopsy
Small tissue sample examined to determine type and extent of kidney damage. Used when cause is unclear.
Treatment
Treatment focuses on slowing progression, managing symptoms, and treating complications. Approach depends on CKD stage and underlying cause:
Treating Underlying Causes
Blood Pressure Control
- Target: Usually below 130/80 mmHg
- ACE inhibitors or ARBs preferred (protect kidneys)
- Multiple medications often needed
- Regular monitoring essential
Diabetes Management
- Tight blood sugar control
- A1C target usually below 7%
- SGLT2 inhibitors may slow CKD progression
- Regular monitoring of kidney function
Medications for Complications
Anemia Treatment
- Erythropoietin-stimulating agents (ESAs)
- Iron supplements
- Target hemoglobin levels 10-11 g/dL
Bone Disease Management
- Phosphate binders
- Vitamin D supplements
- Calcium supplements (carefully monitored)
- Medications to lower PTH if elevated
Fluid and Electrolyte Balance
- Diuretics for fluid retention
- Sodium bicarbonate for acidosis
- Potassium management
- Fluid restriction if needed
Kidney Replacement Therapy
Hemodialysis
Blood filtered through machine 3 times weekly. Each session lasts 3-5 hours. Can be done at dialysis center or home.
Peritoneal Dialysis
Uses abdominal lining to filter blood. Can be done at home. Continuous or overnight options available.
Kidney Transplant
Best long-term solution for eligible patients. Requires matching donor and lifelong immunosuppression.
Living With CKD
Managing CKD requires lifestyle changes and ongoing medical care to maintain quality of life and slow progression:
Dietary Management
- Protein: May need restriction in advanced stages
- Sodium: Limit to 2,300mg daily or less
- Potassium: Monitor and restrict if levels high
- Phosphorus: Limit in advanced stages
- Fluids: May need restriction with reduced urine output
- Calories: Adequate intake to prevent malnutrition
Lifestyle Modifications
- Exercise: Regular moderate activity as tolerated
- Weight management: Maintain healthy weight
- Smoking cessation: Critical for slowing progression
- Alcohol limitation: Moderate or avoid
- Stress management: Important for blood pressure control
Medical Management
- Regular monitoring: Blood tests, urine tests, blood pressure
- Medication adherence: Take all prescribed medications
- Vaccination: Flu, pneumonia, hepatitis B vaccines
- Avoid nephrotoxins: NSAIDs, certain antibiotics
- Dental care: Prevent infections
Emotional Support
- Join support groups
- Consider counseling for adjustment
- Maintain social connections
- Plan for future care needs
Prevention
Many cases of CKD can be prevented or slowed through healthy lifestyle choices and managing risk factors:
Primary Prevention
- Control blood pressure: Regular monitoring and treatment
- Manage diabetes: Keep blood sugar in target range
- Healthy diet: Low sodium, balanced nutrition
- Regular exercise: 150 minutes moderate activity weekly
- Maintain healthy weight: Reduce strain on kidneys
- Don't smoke: Smoking damages blood vessels
- Limit alcohol: Moderate consumption only
Early Detection
- Regular screening: If at risk (diabetes, hypertension)
- Annual checkups: Include kidney function tests
- Know your numbers: Blood pressure, blood sugar, GFR
- Family history awareness: Increased vigilance if CKD in family
Medication Safety
- Avoid overuse of NSAIDs
- Inform doctors about kidney health
- Adjust medication doses as needed
- Avoid herbal supplements without approval
Complications
CKD affects almost every part of the body and can lead to serious complications:
Cardiovascular Disease
Leading cause of death in CKD. Includes heart attack, stroke, heart failure. Risk increases as kidney function declines.
Anemia
Reduced red blood cell production causes fatigue, weakness, and decreased quality of life. Common in moderate to severe CKD.
Bone Disease
Mineral and bone disorder leads to weak bones, fractures, and vascular calcification. Caused by phosphate retention and vitamin D deficiency.
High Blood Pressure
Both a cause and complication. Creates vicious cycle of kidney damage and hypertension.
Fluid Retention
Leads to swelling, shortness of breath, and heart strain. Can cause pulmonary edema in severe cases.
Electrolyte Imbalances
- Hyperkalemia: High potassium can cause heart arrhythmias
- Metabolic acidosis: Acid buildup affects multiple organs
- Hyperphosphatemia: Contributes to bone disease
Malnutrition
Poor appetite, dietary restrictions, and nausea lead to protein-energy wasting.
Pregnancy Complications
Increased risk of preeclampsia, premature birth, and low birth weight.