Chronic Kidney Disease Lecture Review

Chronic Kidney Disease (CKD) Overview

Lecture Information

  • Course: PHOL 483 Translational Physiology

  • Date: Thursday, Jan 15, 2024

  • Time: 10:00 – 11:00 AM

  • Instructor: Jinhua Zhao, MD, Assistant Professor of Medicine, CWRU School of Medicine, Renal Division, Cleveland VA Medical Center

Introduction to CKD

  • Definition: Chronic Kidney Disease (CKD) is characterized by a gradual loss of kidney function over time.

  • Primary Function of Kidneys: The primary role of the kidneys is to filter and excrete waste products from the body.

  • Assessment of Kidney Function: To evaluate kidney function, healthcare providers measure the amount of waste products present in the blood, primarily through the Glomerular Filtration Rate (GFR).

Glomerular Filtration Rate (GFR)

  • Definition: GFR is a crucial test that estimates how well the kidneys are filtering waste from the blood.

  • Significance: A higher concentration of waste products in the blood reflects a lower GFR, indicating diminished kidney function.

  • Normal GFR Range: Normal GFR is generally considered to be > 90 ml/min/1.73 m².

CKD Stages

  1. Stage 1: GFR > 90 ml/min - Normal or High

  2. Stage 2: GFR 60-89 ml/min - Mildly Decreased

  3. Stage 3:

    • G3a: GFR 45-59 ml/min - Mildly to Moderately Decreased

    • G3b: GFR 30-44 ml/min - Moderately to Severely Decreased

  4. Stage 4: GFR 15-29 ml/min - Severely Decreased

  5. Stage 5: GFR < 15 ml/min - Kidney Failure

Epidemiology of CKD

  • Prevalence in North America: About 10% of North Americans are affected by CKD; over 26 million individuals have some form of kidney disease.

  • Age Factor: 25% of North Americans over the age of 65 have some form of CKD.

  • Kidney Failure and Transplants: 20% of individuals with kidney failure are on the transplant waiting list.

Causes of CKD

  • Main Causes:

    • Diabetes: 45%

    • Hypertension: 25%

    • Immune/inherited conditions: 15%

    • Other factors: 15%

Key Data and Statistics

  • 2017 CKD Prevalence: 11.1% worldwide; CKD is twice as prevalent as diabetes and 20 times more common than cancer.

  • Funding and Healthcare Costs: The average Medicare cost per patient escalates with CKD severity, noted at 125K for stage 5 where costs are highest due to comorbidities.

Renal Function Assessment

  • Why GFR is Best Measure: GFR is proportional to the number of functioning nephrons. Healthy individuals < 40 years typically have around 2 million nephrons; GFR generally declines with age due to nephron loss.

  • Limitations of Serum Creatinine: Serum creatinine alone is an inadequate indicator of GFR; it must be adjusted for patient factors like age, race, and sex using estimating equations such as CKD-EPI and MDRD.

Conditions Indicating Kidney Damage

  • Albuminuria: The presence of albumin in urine, indicating the glomerular filtration barrier's compromise. Detected if urine albumin exceeds 30 mg/24 hours or in spot collection of urine albumin-to-creatinine ratio.

  • Hematuria: The presence of erythrocytes in urine. Dysmorphic erythrocytes suggest damage to the glomeruli.

Risk Factors for CKD

  • Primary Risks: Diabetes, Hypertension

  • Additional Risks: Family history of CKD, advancing age, systemic infections, loss of kidney mass, autoimmune diseases.

Progression and Management of CKD

  • Diabetic Nephropathy Progression: Diabetes onset leads to glomerular filtration rate decreases over time, culminating in end-stage renal disease (ESRD).

  • Impact of Treatment: The use of ACE inhibitors and SGLT2 inhibitors has therapeutic advantages by reducing the progression of CKD through mechanisms such as lowering intraglomerular pressure (PGC).

End-Stage Renal Disease (ESRD)

  • Homeostasis Changes: Reduced renal function leads to the retention of nitrogenous waste, fluid/electrolyte imbalances, acid-base disturbances, and hypertension.

  • Definitions:

    • Azotemia: A buildup of nitrogen waste in blood (measured by BUN and serum creatinine).

    • Uremia: Symptoms due to the accumulation of uremic toxins signify multiple organ dysfunction.

Renal Replacement Therapies

  • Types:

    • Hemodialysis

    • Peritoneal Dialysis

    • Kidney Transplantation

  • Hemodialysis Procedure: Involves the removal of blood for cleansing through a dialyzer and returning cleaned blood to body.

Conclusion: Learning Objectives and Key Points

  1. GFR is the best clinical measure of renal function.

  2. Serum creatinine and estimated GFR (eGFR) are critical for assessing renal function.

  3. Recognize the implications of albuminuria and hematuria as indicators of glomerular barrier damage.

  4. Comprehension of CKD stages and leading causes is crucial for management.

  5. Understanding the physiological principles of ACE inhibitors and SGLT2 inhibitors in CKD treatment is essential.

  6. Identification of cardinal changes in ESRD is vital for patient care strategies.

  7. Comparison of dialysis and transplantation as renal replacement methods highlights options available to patients.