Chronic kidney disease

Chronic kidney disease (CKD) is defined as an abnormality of the kidney structure or function for ≥ 3 months. The most common causes of CKD in the United States are diabetes mellitus, hypertension, and glomerulonephritis. Since the kidneys have exceptional compensatory mechanisms, most patients remain asymptomatic and are unaware of their condition until their kidney function is significantly impaired. Patients typically present with symptoms of fluid overload (e.g., peripheral edema) and uremia. Laboratory evaluation shows hyperkalemia, hyperphosphatemia, and hypocalcemia, as well as metabolic acidosis. Management focuses mainly on treating the underlying disease and preventing possible complications, e.g., treating hypertension, avoiding nephrotoxic substances, and maintaining adequate hydration. If chronic kidney disease progresses to end-stage renal disease (ESRD), renal replacement therapy (dialysis) or a kidney transplant is necessary.

Causes of CKD in the US
Diabetic nephropathy	Most common cause, accounts for 44% of cases in the US
Hypertensive nephropathy	28%
Glomerulonephritis	8%
Polycystic kidney disease/hereditary	2%
Urological disease	0.5%
Other causes: amyloidosis, toxins, chronic inflammation

References:^[3][4][5]

• Patients are often asymptomatic until later stages.
• Hypertension
• Peripheral edema
• Pulmonary edema (usually interstitial pulmonary edema)
• Clinical features of uremia
  • Fatigue, weakness, loss of appetite, headaches
    • Uremic fetor
  • Pigmented spots
  • Pruritus
  • Anemia
  • Uremic pericarditis
    • Friction rub on auscultation
    • Diagnostics: Uremic pericarditis does not show typical ECG changes such as diffuse ST-segment elevation.
  • Pleuritis
  • Asterixis
  • Encephalopathy; : seizures, somnolence, coma
  • Peripheral neuropathy: paresthesias
  • Gastrointestinal symptoms: nausea, vomiting
  • ↑ Risk of infection: leukocyte dysfunction
  • ↑ Bleeding tendency secondary to platelet dysfunction
• Chronic kidney disease-mineral and bone disorder (CKD-MBD): abnormalities of mineral or bone metabolism in the setting of chronic renal disease
  • Etiology: mostly due to secondary hyperparathyroidism; → high-turnover renal osteodystrophy or osteitis fibrosa cystica
  • Clinical features: : weakness, fractures, bone pain, avascular necrosis

Patients develop secondary hyperparathyroidism and subsequent renal osteodystrophy due to hyperphosphatemia, hypocalcemia, and the insufficient production of vitamin D!

References:^{[6][7][8][9][10][11][12][13]}

• Blood
  • ↑ Creatinine and BUN
  • Electrolytes: hyperkalemia, hyperphosphatemia, hypocalcemia
  • Monitor blood pH for metabolic acidosis
  • ↓ Calcitriol levels
  • ↑ Parathyroid hormone (PTH)
  • Coagulation testing: ↔︎ PT, PTT, platelet count, ↑ bleeding time caused by uremic coagulopathy
  • Anemia of chronic kidney disease: ↓ hemoglobin, ↔︎ MCV
    • Pathophysiology: ↓ erythropoietin → decreased stimulation of RBC production → normocytic, normochromic anemia
• Urinalysis: : possibly abnormal urine sediment (see nephritic sediment, nephrotic sediment)
• Ultrasound: shrunken kidneys and fibrotic parenchyma
• Renal biopsy: sometimes indicated to determine the underlying cause

In chronic renal disease, close surveillance of serum potassium values as well as calcium and phosphate values is essential!References:^{[13][14][15][16]}

• Diet
  • Salt restriction in patients with edema or hypertension
  • See treatment of hyperkalemia.
  • See treatment of acid-base disorders.
• Nephrotoxic substances avoidance
  • NSAIDs
  • Nicotine
  • Sulfonamide antibiotics, aminoglycosides, vancomycin
  • Acyclovir
  • Cisplatin
  • Others (e.g., lead, amphetamines, amphotericin B, radiographic contrast material)
• Strict blood pressure control
  • Well-controlled blood pressure is essential to prevent disease progression.
  • See treatment of hypertension.
• Vaccinations
  • All patients with CKD
    • Pneumococcal vaccine every 5 years
    • Influenza vaccine annually
  • Susceptible patients: hepatitis B vaccine (see high-risk groups for HBV infection)

• Special patient groups
  • End-stage renal disease
    • Dialysis until a renal transplant is available
  • Anemia of chronic kidney disease
    • Administer synthetic EPO, possibly in conjunction with iron replacement depending on serum ferritin and transferrin values.
      • Adverse effects: increased risk of thrombosis, increase in blood pressure
    • RBC transfusion may be needed in cases of EPO resistance
  • Metabolic diseases
    • Hyperlipidemia: statins
    • Diabetes mellitus: Insulin dose may have to be decreased.
    • Restrict protein intake to 0.8–1.0 g/kg/day
  • Actively bleeding or about to undergo a surgical procedure
    • Desmopressin (DDAVP): first-line therapy
    • Cryoprecipitate: life-threatening bleeding resistant to treatment with desmopressin
    • Conjugated estrogens: for chronic control of bleeding
    • Correction of anemia
    • Dialysis

References:^{[13][14][17][18][19][20][16][21][21]}