Chronic Kidney Disease (CKD)

Snapshot

• A 54-year-old man presents to his primary care physician with chest pain. His chest pain began approximately 2 weeks ago and worsens when taking deep breaths. He reports that sitting up and leaning forward improves his symptoms and that his chest pain is not associated with exertion. He says that his symptoms are associated with mild shortness of breath and fatigue. Medical history is significant for type 2 diabetes mellitus, hyperlipidemia, and hypertension. He has been non-adherent to his medications. Social history is notable for smoking 1 pack of cigarettes per day for 20 years. Vital signs are significant for a blood pressure of 163/112 mmHg. On physical examination, there is a pericardial friction rub and peripheral edema. On laboratory testing, his glomerular filtration rate (GFR) 48 mL/minute/1.73 m².

Introduction

• Clinical definition
  • chronic kidney disease (CKD) describes abnormalities in kidney structure or function occuring for > 3 months
    • e.g., glomerular filtration rate (GFR) < 60 mL/minute/1.73 m² for > 3 months 
    • when CKD requires renal transplantation or dialysis, the patient is said to have end-stage renal disease (ESRD)
• Epidemiology
  • incidence
    • 1 in 10 American adults have some form of CKD
  • risk factors
    • older age
    • diabetes mellitus
    • hypertension
    • acute kidney injury
    • microalbuminuria or proteinuria
    • overweight or obesity
    • smoking, alcohol, and drug abuse
• Etiology
  • insults that result in renal damage
    • e.g., diabetes mellitus, autoimmune disease (such as lupus), and hypertension
• Pathogenesis
  • in normal conditions
    • the kidneys have the ability to maintain glomerular filtration rate (GFR) in the setting of nephron loss
      • this is accomplished by hyperfiltration and hypertrophy of the remaining nephrons
      • when GFR decreases to 50% there will be an increase plasma substances such as creatinine and urea
  • a number of sequela occur as the GFR continues to decrease such as 
    • hyperkalemia
    • metabolic acidosis
    • normochromic normocytic anemia
      • secondary to decreased synthesis of erythropoietin
    • secondary hyperparathyroidism  
    • hyperphosphatemia
    • hypocalcemia 
      • secondary to decreased hydroxylation of 25-hydroxyvitamin D to calcitriol 
    • impairment of sodium and free water excretion
      • this results in extracellular fluid (ECF) expansion and total-body volume overload
        • this leads to peripheral and pulmonary edema and hypertension
• Prognosis
• typically progressive loss of renal function and may result in ESRD

Presentation

• Symptoms
  • typically asymptomatic in early stages of the disease
  • clinical presentation secondary to uremia include
    • fatigue
    • nausea and vomiting
    • pruritis
    • chest pain
      • secondary to pericarditis or pleuritis
    • seizure
• Physical exam
  • hypertension
  • uremic frost 
  • growth retardation in children
  • peripheral edema
  • osteitis fibrosa cystica
  • osteomalacia
• “renal rickets”

Imaging

• Renal ultrasound
  • indication
    • considered the first-line imaging modality when working up a patient with CKD
    • used to evaluate between obstructive and intrinsic parenchymal disease
• to assess for retroperitoneal involvement and renal cysts

Studies

• Labs
  • complete blood count (CBC)
    • can see normochromic, normocytic anemia
  • basic metabolic panel
    • ↑ blood urea nitrogen (BUN), creatinine, and potassium
  • ↑ phosphate
  • ↑ parathyroid hormone
  • ↓ calcium
  • ↓ calcitriol
  • cystatin C
    • it is secreted but not reabsorbed
    • an endogenous marker of renal function
  • urine studies
    • to assess for proteinuria
    • can see waxy-casts on urinalysis in patients with ESRD and CKD 
• Biopsy
• percutaneous renal biopsy is typically performed when there is renal impairment (or nephrotic range proteinuria) and the diagnosis is unclear after extensive workup

Differential

• Acute on chronic kidney disease

Treatment

• Conservative
  • protein restriction
    • indication
      • a method of managing dietary protein that may reduce the rate of renal decline
• Medical
  • ACE inhibitors or ARBs
    • indications
      • considered first-line for strict blood pressure control
        • blood pressure goal of < 130/80 mmHg
        • blood pressure control can help delay worsening of CKD
      • to manage proteinuria in patients with diabetic kidney disease
  • vitamin D supplementation
    • indication
      • for prevention and treatment of secondary hyperparathyroidism
  • erythropoiesis-stimulating agent
    • indication
      • can be considered to manage anemia in patients with CKD
        • hemoglobin goal is 10-12 g/dL
  • phosphate binders
    • indication
      • to treat hyperphosphatemia in patients with CKD
  • statins
    • indication
      • used as cholesterol lowering therapy in patients with CKD
  • dialysis
    • indication
      • in patients with severe metabolic acidosis, hyperkalemia, pericarditis, intractable volume overload, and encephalopathy
• Operative
  • renal transplant
    • indication
• a treatment option for patients with CKD

Complications

• Anemia
• Mineral and bone disease
• Hypertension
• Hypervolemia
• Depression
• Cardiovascular disease