Chronic Kidney Disease (CKD)

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 Chronic Kidney Disease (CKD)

Definition

Chronic kidney disease (CKD) is defined as:

Abnormalities of kidney structure or function, present for ≥3 months, with implications for health.

Diagnostic criteria (one or more):

  • Decreased glomerular filtration rate (GFR) <60 mL/min/1.73 m² for ≥3 months
    OR

  • Markers of kidney damage for ≥3 months:

    • Albuminuria (≥30 mg/g creatinine)

    • Urine sediment abnormalities (e.g., hematuria, casts)

    • Electrolyte disturbances due to tubular disorders

    • Structural abnormalities detected by imaging

    • History of kidney transplantation

Epidemiology

  • Prevalence: ~10–15% of adults worldwide.

  • Common in elderly and patients with diabetes or hypertension.

  • CKD increases cardiovascular morbidity and mortality even before end-stage renal disease (ESRD).

Etiology

Category Examples
Diabetic kidney disease Most common cause (~38%)
Hypertensive nephrosclerosis ~26%
Glomerulonephritis e.g., IgA nephropathy, membranous GN
Polycystic kidney disease Autosomal dominant
Tubulointerstitial disease Drugs, reflux nephropathy, heavy metals
Obstructive uropathy Prostate enlargement, stones

Pathophysiology

  • Progressive loss of functioning nephrons → compensatory hyperfiltration in remaining nephrons.

  • Persistent hyperfiltration → glomerulosclerosis and further nephron loss (vicious cycle).

  • Systemic consequences:

    1. ↓ Erythropoietin → anemia.

    2. ↓ Vitamin D activation → hypocalcemia.

    3. ↑ Phosphate retention → secondary hyperparathyroidism (CKD–mineral bone disorder).

    4. ↓ Clearance of uremic toxins → uremic syndrome.

Clinical Features

Early (often asymptomatic)

  • Fatigue, anorexia, nocturia, mild HTN.

Late (advanced disease)

  • Volume overload: peripheral or pulmonary edema.

  • Uremic symptoms: pruritus, nausea, confusion, metallic taste, hiccups.

  • Pale skin (anemia), sallow discoloration.

  • Muscle cramps, restless legs.

  • Pericarditis (uremic pericarditis).

  • Kussmaul respiration in metabolic acidosis.

Investigations

1. Laboratory tests

Test Findings / Use
Serum creatinine & eGFR Main measure of kidney function
Urine albumin-to-creatinine ratio (ACR) Detects albuminuria
CBC Normocytic anemia (↓ EPO)
Electrolytes ↑ K⁺, ↑ phosphate, ↓ Ca²⁺, ↑ bicarbonate deficit
PTH, vitamin D Assess bone-mineral disorder
Lipid profile Dyslipidemia common in CKD

2. Imaging

  • Renal ultrasound: small, echogenic kidneys (except in polycystic disease).

  • CT/MRI: to rule out obstruction or cystic disease.

CKD Staging (KDIGO 2024)

GFR category GFR (mL/min/1.73 m²) Description
G1 ≥90 Normal or high (if kidney damage present)
G2 60–89 Mild decrease
G3a 45–59 Mild–moderate decrease
G3b 30–44 Moderate–severe decrease
G4 15–29 Severe decrease
G5 <15 Kidney failure (ESRD if symptomatic)

Albuminuria staging:

Category ACR (mg/g) Description
A1 <30 Normal to mildly increased
A2 30–300 Moderately increased
A3 >300 Severely increased

Complications

1. Cardiovascular

  • Hypertension

  • Left ventricular hypertrophy

  • Accelerated atherosclerosis → ↑ risk of MI and stroke

2. Hematologic

  • Normocytic normochromic anemia (↓ EPO)

  • Platelet dysfunction → bleeding tendency

3. Electrolyte/Acid-base

  • Hyperkalemia

  • Metabolic acidosis (due to ↓ ammonium excretion)

4. CKD-Mineral Bone Disorder (CKD-MBD)

  • ↓ Vitamin D activation → ↓ Ca²⁺ absorption.

  • ↑ Phosphate → ↑ PTH → secondary hyperparathyroidism.

  • Bone pain, fractures, vascular calcifications.

5. Neurologic

  • Peripheral neuropathy, restless legs.

  • Uremic encephalopathy (in advanced CKD).

6. Endocrine/Metabolic

  • Insulin resistance, dyslipidemia.

  • Decreased clearance of drugs and toxins.

Management

1. Identify and treat underlying cause

  • Tight glycemic control in diabetics (HbA1c <7%).

  • Control blood pressure (<120 mmHg systolic preferred).

2. Slow progression of CKD

  • ACE inhibitors / ARBs → reduce intraglomerular pressure and proteinuria.

  • SGLT2 inhibitors → delay progression in diabetic and non-diabetic CKD.

  • Avoid nephrotoxins (NSAIDs, contrast, aminoglycosides).

3. Manage complications

Complication Management
Anemia Erythropoiesis-stimulating agents (EPO) + iron supplementation
CKD-MBD Phosphate binders, vitamin D analogs, calcimimetics
Hyperkalemia Dietary restriction, loop diuretics, sodium zirconium cyclosilicate if severe
Acidosis Oral sodium bicarbonate
Fluid overload/HTN Loop diuretics, low-salt diet

4. Lifestyle and Dietary

  • Low sodium (<2 g/day)

  • Moderate protein intake (0.8 g/kg/day)

  • Restrict phosphate and potassium in advanced stages

  • Avoid smoking, manage dyslipidemia (statins)

End-Stage Kidney Disease (ESKD)

Definition:

  • GFR <15 mL/min/1.73 m² with uremic symptoms.

Management options:

  1. Renal replacement therapy (RRT):

    • Hemodialysis

    • Peritoneal dialysis

    • Kidney transplantation (preferred if candidate)

  2. Palliative care for patients not eligible for dialysis.

Special Populations

Diabetes Mellitus

  • SGLT2 inhibitors (empagliflozin, dapagliflozin) reduce CKD progression.

  • Monitor for euglycemic ketoacidosis.

Elderly

  • Adjust drug doses to eGFR.

  • Avoid overdiuresis and nephrotoxic drugs.

Prognosis

  • CKD is progressive but can be slowed by early detection and aggressive management.

  • Mortality is mainly due to cardiovascular disease rather than renal failure itself.


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