Renal Disease in Children (Nephrotic and Nephritic Syndrome)

Essentials

• Suspect renal disease and perform urine dipstick tests if a child develops oedema.
• Proteinuria in association with oedema suggests nephrotic syndrome, proteinuria and haematuria nephritic syndrome.
• Any child with significant proteinuria and/or haematuria shown by dipstick test and oedema should be referred as an emergency case to specialized care.

Idiopathic nephrotic syndrome in children

• The most common glomerular disease in children
• The aetiology is unknown.
• The usual age at onset is 2 to 5 years. About 80% of patients are younger than 6 years old.
• The incidence is about 2/10 000 children, and the disease is more common in boys (3:2).
• In infants, particularly those below the age of 6 months, nephrotic syndrome is due to congenital and often hereditary diseases.

Symptoms and findings

• Generalized oedema is usually observed in the lower extremities, the face, particularly the periorbital area, and the abdomen. Gravity affects the location of oedema: in the morning, oedema can be found particularly in the facial area, in the evening in the ankles.
• There may be ascites or pleural effusion without other oedema.
• There may be oedema in the scrotal or vulvar area.
• Increase in weight
• The circulating blood volume should be assessed because in prolonged conditions there may be hypovolaemia. The patient may have concomitant oedema and hypovolaemia.
• A demarcation line in the temperature of the extremities is a good indicator of hypovolaemia. Capillary refill of the nail bed is also reduced in these cases.
  • Abdominal pain may be another indicator of hypovolaemia.
• Oedema is rare in patients with plasma albumin levels exceeding 20 g/l.
• Blood pressure is usually normal.

Diagnosis

• A urine dipstick test is sufficient in outpatient care. If clear proteinuria is found in a patient with oedema, they should be referred for further hospital examinations.
• The patient has marked proteinuria. The protein-to-creatinine ratio in urine is > 200 mg/mmol Interpretation of Urine Test Results in Children.
• Hypoalbuminaemia will develop if the level of proteinuria is so high that the liver is not capable of producing new albumin to replace the loss. In a patient of adult size, this occurs at a protein excretion equivalent to about 3-5 g/day.
  • The amount of protein excreted in urine may be as high as 30-50 g/day.
  • At the primary stage, plasma albumin concentrations are usually < 25 g/l and often well below this.
• Patients typically have no significant haematuria. Microscopic haematuria is found in about 20% of patients.
• Casts (epithelial cell or fatty casts) may be found in urine.
• A urinary sodium test will help to assess hypovolaemia.
  • Urinary sodium concentrations < 10 mmol/l strongly suggest a reduced blood volume.
  • In patients with urinary sodium > 20 mmol/l hypovolaemia is unlikely (unless the patient has been given diuretics).
  • However, urinary sodium tests are rarely available during on-call hours.
• Haemoglobin and haematocrit levels also help to assess hypovolaemia.
• Urinary creatinine concentration may be increased, suggesting reduced excretion of urine.
• Hyperlipidaemia is a common finding.
• IgG levels are low, IgM levels usually elevated.
• Complement levels are normal.
• Plasma urea and creatinine concentrations are usually normal but may be slightly increased in patients with hypovolaemia (prerenal azotaemia).
• Plasma sodium and potassium concentrations are normal.

Treatment Non-Corticosteroid Treatment for Steroid-Sensitive Nephrotic Syndrome in Children, Interventions for Idiopathic Steroid-Resistant Nephrotic Syndrome in Children

• Treatment is usually started in hospital.
• In patients with clear circulating hypovolaemia, fluid should be administered in the form of albumin 5% (1 g/kg, e.g. a child weighing 15 kg would be given 15 g = 300 ml albumin 5%) over 2-4 hours.
• Due to increased risk of thrombosis, bed rest should not be recommended.
• For patients with oliguria and clearly increasing weight or significant oedema, ascites or pleural effusion, albumin 20% at a dosage of 1 ml/kg in 20-30 min + 0.5 mg/kg (up to 20 mg) furosemide can be given intravenously 4-6 times a day.
• Blood pressure and pulse should be monitored regularly during treatment to assess the circulating blood volume.
• If the patient has no volume depletion, the amount of maintenance fluid can be limited to 70% of the calculated maintenance fluid requirement (calculated according to the Holliday-Segar method) to reduce loss of protein.
• A diet low in salt (no added salt) should be followed, as far as possible.

Nephritic syndrome