Chronic kidney disease

Definition

Presence of kidney damage or decreased kidney function for three months with implication for health

• GFR less than 60mL/min or
• Proteinuria, albuminuria, renal tubular disorder or abnormalities detected by imaging or histology

CKD may lead into problems regarding

• Excretion of urea/ creatinine/waste products
• Electrolyte balance (Na+, K+, Ca2+, PO42-, Mg2+)
• Acid-base homeostasis (HCO3-, H+)
• Maintenance of extracellular fluid volume (and hence blood pressure)
• Promotion of red cell production (via erythropoietin)
• Vitamin D metabolism (and hence bone production)

GFR estimation (eGFR)

eGFR = kx height (cm)/ S-creatinine (mg/dL)
k=0.45 in infants, K=0.55 in children and adolescent girls, k=0.7 in adolescent boys

Classification

The staging cannot be used for children under two years of age because their normal range of GFR is lower than in older children.

Causes

• Congenital anomalies
  • Obstructive uropathy
  • Renal hypoplasia
  • Reflux nephropathy
  • Polycystic kidney disease
• Glomerular diseases
  • Primary glomerulonephritis: Focal segmental glomerulosclerosis (FSGS) is the most common glomerulonephritis causing CKD
  • Secondary causes: HIV nephropathy (stage four disease) and lupus nephritis
• Hemolytic Uremic Syndrome
• Hereditary renal diseases (cystinosis, oxalosis, Alport's syndrome)
• Not resolved Acute Kidney Injury

Important points in history

• Family history of renal disease or hypertension
• Growth history
• Polyuria (congenital anomalies) or hematuria (glomerulonephritis)
• Elevated blood pressure (ask about headaches, seizures, visual disturbance)
• Recurrent urinary tract infections
• Unexplained anemia
• Edema
• Usually the child is asymptomatic until eGFR <30mL/min. Weakness, anorexia, vomiting, cognitive disturbance are signs of low eGFR
• past medical history of
  • Urinary tract infections
  • Any serious illnesses
  • Family history

Important points on examination

• Nutritional status, height, weight
• Pubertal status
• Blood pressure
• Pallor
• Signs of fluid overload
• Bone deformities (Vit D
• Signs of immunosuppression or multisystem disease (rash, arthritis)

Investigations

• Urine dipstick
• Creatinine, K and Na
• FBC
• Albumin
• HIV-test, hepatitis B and C
• Blood gases (acidosis?)
• Calcium, phosphat, PTH, if possible (private laboratories do)
• Cholesterol levels, if possible
• Renal ultrasound (look for hydronephrosis, structural anomalies, inflammation, renal size)
• Renal biopsy (very rarely possible)

Complications

• Terminal decline in renal function with profound clinical deterioration
• Anaemia
• Hypertension
• Hyperkalemia
• Fluid overload
• Acidosis
• Mineral and bone disorder
  Growth failure, avascular necrosis, skeletal fractures and deformities, andvascular calcifications
• Dyslipidemia
• Left ventricular hypertrophy
• Growth impairment
• Platelet dysfunction - bleeding tendency
• Uremic pericarditis

Treatment

Treat reversible causes

• Obstruction
• Stop nephrotoxic drugs (NSAIDs and tenofovir)

Prevent the progression of kidney disease

• Salt restriction
• ACE-inhibitors, especially if proteinuria. Consider to stop if eGFR <30mL/min (risk of hyperkalemia – use only if K and Crea can be monitored regularly)
• Calcium channel blockers (Nifedipine or Amlodipine)
• Diuretics: First line Furosemide. HCT is not effective, if eGFR < 30mL/min. Avoid spironolactone (hyperkalemia)
• Beta blockers (Atenolol)

• ACE-inhibitors. See above.

Treat the complications of CKD

• Rule out other causes of anemia
• Iron supplements (CKD patients often have iron deficiency)
• Consider Erythropoietin stimulating agents (EPO), if available
• Blood transfusions

• Low potassium diet (avoid bananas, tomatoes, unboiled potatoes (K stays in potatoes if fried or baked - so boil first), citrus fruits)
• Furosemide
• Resonium (Sodium Polystyrene Sulfonate), if available

• Sodium bicarbonate (or baking soda)
• HCO3 goal is about 20mmol/L
• Treating acidosis may decrease nausea and vomiting

• Salt restriction
• Furosemide 0.5-2mg/kg
• Hydrochlorothiazide, if eGFR > 30mL/min

• Low phosphat diet
• Calciumcarbonate 500mg OD before/during meals to bind dietary phosphat
• Vitamin D (ergocalciferol) 400 IU per day
• If PTH is very high (>5 times upper limit) despite Ca and VitD substitution
  • Weight <10kg - 0.05 microgram every other day
  • Weight 10-20kg - 0.1-0.15 microgram per day
  • Weight 20kg - 0.25 microgram per day

• Low fat, not long-chain triglycerides, but avoid malnutrition!!
• Statins are not recommended for children under 10 years of age

• Protein restriction is not recommended
• Multivitamin

Progression

More rapid if

• Proteinuria
• Hypoalbuminemia
• Elevated blood pressure
• Dyslipidemia
• Anemia

Monitoring and follow-up

• Children with CKD should be regularly checked for growth and well-being, blood pressure, anemia, and development of bone disease
• Follow up visits in renal clinic
• If CKD stage 4 or 5, refer to palliative care