Paediatrics chapters
Chronic kidney disease in children
Long-standing kidney damage in a child: the definition and stages, why congenital anomalies lead the causes, how growth, blood, bone and blood pressure suffer, and how each problem is treated up to dialysis and transplant.
- CKD is kidney damage or GFR under 60 mL/min/1.73 m² for more than 3 months, staged 1 to 5 by GFR, with stage 5 (GFR under 15) being end-stage disease.
- Under 10 years the commonest causes are congenital anomalies (CAKUT): hypodysplasia, posterior urethral valves, reflux nephropathy; after 10 years glomerular disease (FSGS, GN) takes over.
- Key problems are growth failure, anaemia (low erythropoietin), renal osteodystrophy, acidosis, hypertension; the best treatment for end-stage disease is transplantation.
On this page
Overview
Chronic kidney disease (CKD) has replaced the older terms chronic renal failure and chronic renal insufficiency. In children it matters because the damaged kidneys must support a growing body: CKD stunts growth, softens bone, causes anaemia and hypertension, delays puberty and affects school performance. Many children reach end-stage kidney disease (ESRD), and the goal then is a kidney transplant.
Definition
CKD is either of the following for more than 3 months:
- Evidence of kidney damage, such as:
- Albuminuria (over 30 mg/24 hours) or proteinuria.
- Abnormal urine sediment (dysmorphic red cells, red or white cell or granular casts).
- Abnormal imaging: polycystic or dysplastic kidneys, hydronephrosis from obstruction, cortical scars with reflux, small bright kidneys, masses, renal artery stenosis.
- Abnormal histology (e.g. FSGS, lupus nephritis).
- GFR below 60 mL/min/1.73 m².
Estimating GFR
- Serum creatinine depends on muscle mass, so it rises with age; normal values in infants are much lower than in adults.
- GFR is low at birth and reaches adult levels (100 to 120 mL/min/1.73 m²) by about 1 to 2 years.
- The revised (bedside) Schwartz formula (Nelson) is used in children:
eGFR (mL/min/1.73 m²) = 0.413 × height (cm) ÷ serum creatinine (mg/dL)
It works best when muscle mass is normal and renal function is stable. Akbar gives the older form, in which the constant k changes with age and sex (smallest in preterm babies, larger in adolescent boys).
Boy, height 120 cm, serum creatinine 1.6 mg/dL
eGFR = 0.413 × 120 ÷ 1.6 = 31 mL/min/1.73 m²
This lies in the 30 to 59 band → CKD stage 3
Creatinine alone misleads in small children. A creatinine of 1.0 mg/dL may be normal in a teenager but means major loss of function in a toddler.
Staging (KDOQI)
| Stage | GFR (mL/min/1.73 m²) | Description |
|---|---|---|
| 1 | 90 or more | Kidney damage, normal GFR |
| 2 | 60 to 89 | Mild reduction |
| 3 | 30 to 59 | Moderate reduction |
| 4 | 15 to 29 | Severe reduction |
| 5 | Under 15 or on dialysis | End-stage renal disease |
These GFR bands apply from 2 years of age. Most complications appear from stage 3, become numerous in stage 4, and stage 5 needs dialysis or transplant. KDIGO (2012) adds albuminuria as a marker of severity and prognosis.
Causes
| Group | Examples |
|---|---|
| Congenital anomalies (CAKUT) | Renal hypoplasia and dysplasia, posterior urethral valves, reflux nephropathy, bilateral pelviureteric or vesicoureteric junction obstruction, neurogenic bladder |
| Glomerular disease | FSGS, glomerulonephritis (idiopathic, SLE, Henoch-Schönlein purpura, hepatitis B or C, HIV), Alport syndrome, congenital nephrotic syndrome |
| Hereditary | Autosomal recessive and dominant polycystic kidney disease, nephronophthisis |
| After AKI | Haemolytic uraemic syndrome, cortical necrosis |
| Metabolic and inherited tubular | Cystinosis, primary hyperoxaluria, Bartter syndrome, Dent disease |
| Acquired | Stones (nephrolithiasis) |
CAKUT is the commonest cause of CKD from birth to 10 years; after 10 years acquired diseases such as FSGS and glomerulonephritis become commoner (Nelson).
Clinical features
Clues from the cause
- CAKUT: polyuria, polydipsia, salt wasting, recurrent UTIs, poor urinary stream (valves).
- Glomerular disease: haematuria, proteinuria, oedema, hypertension.
Features of advanced CKD (stage 3 to 5)
Anorexia, fatigue, growth failure, pallor, hypertension, bone pain and deformity, headache. When GFR falls below 15: itching, severe acidosis, hyperkalaemia, heart failure, pulmonary oedema, pericarditis and altered consciousness. Infants and young children may develop uraemic encephalopathy.
Complications and why they happen
| Complication | Mechanism | Treatment |
|---|---|---|
| Growth failure | Poor intake, acidosis, anaemia, renal osteodystrophy, salt and water loss, resistance to growth hormone (low IGF-1), steroids | Extra calories, correct acidosis and bone disease, recombinant growth hormone |
| Anaemia | Mainly low erythropoietin; also iron and folate deficiency, shortened red cell life, marrow suppression; normocytic normochromic | Erythropoietin and iron; slow packed-cell transfusion if severe |
| Renal osteodystrophy | Low 1,25-dihydroxyvitamin D → low calcium → high PTH; later phosphate retention pushes PTH higher → secondary hyperparathyroidism, osteitis fibrosa, rickets | Calcium carbonate as phosphate binder with meals, low-phosphate diet, active vitamin D (alfacalcidol or calcitriol), calcium supplements |
| Metabolic acidosis | Bicarbonate wasting and poor acid excretion | Alkali (sodium bicarbonate) once serum bicarbonate is below about 20 mEq/L |
| Hypertension and LVH | Salt and water overload, excess renin | Salt restriction, diuretics, antihypertensives |
| Hyperkalaemia | Late, in advanced disease | Low-potassium diet (limit bananas, citrus), furosemide, sodium polystyrene sulfonate |
| Hyponatraemia / salt wasting | Dysplastic or obstructed kidneys lose salt | Sodium supplements |
| Delayed puberty | Disturbed gonadotrophin secretion | |
| Bleeding | Poor platelet function | |
| Infection | UTI is the commonest | Prompt antibiotics |
Anaemia of CKD is mainly due to erythropoietin deficiency, and the bone disease is driven by low active vitamin D, low calcium and high phosphate causing secondary hyperparathyroidism.
Bone signs (renal rickets)
- Infants: rachitic rosary, widened wrists and knees, Harrison sulcus.
- Older children: knock knees (genu valgum), bowed tibiae, scoliosis, fractures.
- Biochemistry: low calcium, high phosphate, high alkaline phosphatase, high PTH.
Nutritional rickets has low or normal phosphate; renal (CKD) rickets has high phosphate with high PTH.
Investigations
- Severity: full blood count, urea, creatinine, electrolytes, calcium, phosphate, alkaline phosphatase, albumin, uric acid, blood gas (pH, bicarbonate), intact PTH, eGFR by Schwartz.
- Bone: X-ray of left hand and wrist (bone age, rickets).
- Heart: chest X-ray, ECG, echocardiography (LVH).
- Cause: urinalysis and culture, ultrasound (small kidneys in chronic disease), MCUG (valves, reflux), DMSA (scars), DTPA or MAG3 (obstruction), C3, C4, ANA, anti-dsDNA, renal biopsy, specific metabolic tests (e.g. cystine level in white cells, oxalate).
Management
Aims before dialysis: protect remaining kidney function, prevent and treat complications and keep the child growing.
Nutrition
- Calories at least 100% of the recommended amount for age; poor calorie intake is a major cause of poor growth once function falls below half.
- Protein restricted only in severe uraemia; give high biological value protein (eggs, chicken, fish), more generous in growing children.
- Reduce milk if phosphate is high; add water-soluble vitamins.
Fluid and salt
- Fluid restriction is rarely needed because these kidneys often cannot concentrate urine; restrict only with oliguria or heart failure (insensible loss of 400 mL/m²/day plus losses).
- No added salt for most; stricter limits with hypertension or oedema; extra salt for salt-losing dysplastic kidneys.
Specific measures
- Acidosis: oral sodium bicarbonate.
- Bone: calcium carbonate with every meal, alfacalcidol or calcitriol with calcium monitoring (avoid high calcium).
- Anaemia: erythropoietin plus iron.
- Blood pressure: salt restriction, diuretics, beta-blockers, ACE inhibitors (watch potassium).
- Growth: growth hormone if poor growth persists after the above.
- Drugs: adjust doses of renally cleared drugs; avoid nephrotoxins.
- Immunisation: keep up to date (hepatitis B is important before dialysis).
- Avoid factors that worsen CKD: uncontrolled hypertension, dehydration, heart failure, UTI, obstruction, nephrotoxic drugs, low potassium or high calcium.
- Support: school attendance, activities and family counselling; plan renal replacement early.
End-stage disease (stage 5)
| Option | Points |
|---|---|
| Renal transplantation | Best treatment; living (related) donors preferred and do best; successful even in very young children; needs lifelong immunosuppression (infection, nephrotoxicity, cancer risk) |
| Peritoneal dialysis | Done at home by the family; continuous ambulatory PD is the commonest dialysis in children; a bridge to transplant |
| Haemodialysis | Usually three times a week in a unit |
Indications for chronic dialysis include stage 5 CKD, poor growth, and overload, acidosis, electrolyte problems or uraemia not controlled medically.
"Transplant is the target; dialysis is the waiting room."
Prognosis
- Stages 1 and 2 may stay stable but need monitoring.
- Stages 3 and 4 usually progress to ESRD in time; function often worsens during the pubertal growth spurt.
- Children on long-term dialysis have the highest illness and death rates, so early transplant is the aim; most grafts eventually fail but can last many years.
Expect: the definition (damage or GFR under 60 for over 3 months); the revised Schwartz formula and a quick calculation; the five KDOQI stages; CAKUT (hypodysplasia, posterior urethral valves, reflux nephropathy) as the commonest cause in young children; anaemia from low erythropoietin; renal osteodystrophy from low calcitriol, high phosphate and secondary hyperparathyroidism; causes of short stature; treatments such as calcium carbonate, alfacalcidol, erythropoietin, bicarbonate and growth hormone; and transplantation as the treatment of choice.
Quick revision
- CKD: damage or GFR under 60 for more than 3 months; stage 5 is GFR under 15.
- eGFR = 0.413 × height (cm) ÷ creatinine (mg/dL).
- Under 10 years: CAKUT; over 10 years: FSGS and GN.
- Growth failure: calories, acidosis, bone disease, GH resistance.
- Anaemia: erythropoietin lack, iron deficiency; treat with EPO and iron.
- Bone: low calcitriol, high phosphate, high PTH; calcium carbonate and alfacalcidol.
- Acidosis: bicarbonate; hyperkalaemia: diet and resin.
- Hypertension and LVH are common; UTI is the commonest infection.
- Transplant (living donor) is best; PD at home; haemodialysis three times weekly.
Written by The House Job from standard references (Basis of Paediatrics by Pervez Akbar; Nelson Essentials of Paediatrics).
FAQ
What is the commonest cause of chronic kidney disease in children?
Congenital anomalies of the kidneys and urinary tract (hypodysplasia, posterior urethral valves and reflux nephropathy) lead in children under 10; glomerular diseases such as FSGS lead in older children.
Why is the anaemia of CKD normocytic?
It is mainly due to too little erythropoietin from the damaged kidney, so the marrow makes fewer but otherwise normal red cells; added iron deficiency can make it microcytic.
Why does phosphate rise in CKD and why does it matter?
The failing kidney cannot excrete phosphate; the high phosphate lowers calcium and drives parathyroid hormone up, which damages bone, so phosphate is controlled with diet and calcium carbonate binders.
Is dialysis or transplantation better for a child with end-stage disease?
Transplantation is the treatment of choice, preferably from a living donor; dialysis keeps the child alive while waiting but carries the highest long-term illness and death rates.