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Chronic kidney disease

Last updated: March 17, 2021

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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 until kidney function is significantly impaired. Patients typically present with symptoms of fluid overload (e.g., peripheral edema) and uremia (e.g., fatigue, pruritus). Laboratory studies show hyperkalemia, hyperphosphatemia, hypocalcemia, and 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 (i.e., dialysis or kidney transplantation) becomes necessary.

Epidemiological data refers to the US, unless otherwise specified.

  1. Diabetic nephropathy (38%)
  2. Hypertensive nephropathy (26%)
  3. Glomerulonephritis (16%)
  4. Other causes (15%, e.g., polycystic kidney disease; , analgesic misuse, amyloidosis)
  5. Idiopathic (5%)

Reference: [1]

Pathophysiology depends on the underlying condition, any of which will eventually lead to progressive nephron loss, structural damage, and impaired kidney function.

Underlying conditions

Consequences

Patients are often asymptomatic until later stages due to the exceptional compensatory mechanisms of the kidneys.

Manifestations of Na+/H2O retention

Manifestations of uremia

Overview

  • Chronic kidney disease is staged according to the CGA classification based on GFR and albuminuria categories.
  • Higher categories are associated with poorer prognosis.
  • There are two main categories: systemic causes and primary kidney disease
  • Further differentiation based on location within the kidney (glomerular, tuberointerstitial, vascular, or cystic and congenital)

Categories and staging

Estmiated glomerular filtration rate (eGFR) categories [8]
Category eGFR (mL/min/1.73 m2)

Description

G1 > 90 Normal or high
G2 60–89 Mildly decreased
G3a 45–59 Mildly to moderately decreased
G3b 30–44 Moderately to severely decreased
G4 15–29 Severely decreased
G5 < 15 Kidney failure
Albuminuria categories [8]
Category Urinary albumin excretion Description
mg/g mg/mmol
A1 < 30 < 3 Normal to mildly increased
A2 30–300 3–30 Moderately increased (microalbuminuria)
A3 > 300 > 30 Severely increased (macroalbuminuria)
Staging of CKD
GFR category

eGFR

(mL/min/1.73 m2)

Albuminuria category

A1

< 30 mg/g or < 3 mg/mmol

A2

30–300 mg/g or 3–30 mg/mmol

A3

> 300 mg/g or > 30 mg/mmol

G1 > 90 G1A1 G1A2 G1A3
G2 60–89 G2A1 G2A2 G2A3
G3a 45–59 G3aA1 G3aA2 G3aA3
G3b 30–44 G3bA1 G3bA2 G3bA3
G4 15–29 G4A1 G4A2 G4A3
G5 < 15 G5A1 G5A2 G5A3

Interpretation

  • Not considered CKD (unless there is evidence of kidney damage, e.g., imaging showing PCKD)
    • G1A
    • G2A1
  • Mild CKD
    • G1A2
    • G2A2
    • G3aA1
  • CKD
    • G1A3
    • G2A3
    • G3aA2
    • G3bA1
  • End-stage kidney disease
    • G3aA3
    • G3bA2, G3bA3
    • G4A1, G4A2, G4A3
    • G5A1, G5A2, G5A3

Approach [9]

Diagnosing CKD requires the integration of information from clinical presentation, laboratory tests, imaging, and, if necessary, pathology. The following steps should be included in the process:

  1. Thorough review of patient medical records for information suggesting CKD and potential underlying conditions
  2. Physical examination with fluid status, thorough abdominal status, exploration of signs of common comorbidities, and clues of underlying conditions
  3. Laboratory tests (see below) to assess kidney function
  4. Imaging (see “Doppler ultrasound” below) to assess kidney structure
  5. If necessary, kidney biopsy

Laboratory tests

Blood work

Urinalysis

Doppler ultrasound [11]

Doppler ultrasound is the first-line imaging technique for the assessment of kidney structure.

  • Pathological findings
    • ↓ Length and ↓ cortical thickness of kidneys
    • Cysts
    • Calcifications
    • Perfusion and ↓ vascularity

Pathology

  • Renal biopsy: indicated when diagnosis by other means remains inconclusive regarding the underlying condition

Kidney OUTAGES: hyperKalemia, renal Osteodystrophy, Uremia, Triglyceridemia, Acidosis (metabolic), Growth delay, Erythropoietin deficiency (anemia), Sodium/water retention (consequences of chronic kidney disease)

In chronic renal disease, close surveillance of serum potassium, calcium, and phosphate levels is essential.

General measures

Diet

  • Fluid intake: monitor appropriate fluid intake
  • Protein and energy consumption [12]
    • Mediterranean diet, ↑ fruit and vegetable intake
    • Protein restriction to 0.55–0.6 g/kg/day
  • Electrolytes [13]
    • Sodium restriction
    • Potassium intake adjustment (e.g., avoidance of high-potassium foods) to reduce the risk of hyperkalemia (see “Hyperkalemia”)
    • Phosphorus restriction
  • Micronutrients: vitamin D supplementation with cholecalciferol/ergocalciferol [13]

Avoidance of nephrotoxic substances

Vaccination [14]

Pharmacological treatment

Blood pressure

Dyslipidemia [16]

Renal replacement therapy

Chronic kidney disease-mineral and bone disorder (CKD-MBD)

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

Secondary hyperparathyroidism

Anemia of chronic kidney disease

End-stage renal disease (ESRD)

Growth delay and developmental delay in children

Cardiovascular-associated CKD-complications

We list the most important complications. The selection is not exhaustive.

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