Common Paediatric Renal Conditions

Common paediatric renal conditions Few children in South Africa have access to dialysis or renal transplantation, so it is important to recognise kidney disease early enough to prevent progression to end-stage disease. Gertruida van Biljon, MB ChB, MMed(Paed), FCP (Paed) SA, Cert Paediatric Nephrology Professor and Senior Consultant, Department of Paediatrics, Faculty of Health Sciences, University of Pretoria Gertruida van Biljon is a full-time senior consultant in the Department of Paediatrics and Head of the Paediatric Nephrology Unit at Steve Biko Academic Hospital. The Paediatric Renal unit is an accredited paediatric nephrology training unit. Professor Van Biljon has a special interest in the treatment interventions in children with chronic kidney disease, hypertension and nephrotic syndrome. Correspondence to: Gertruida van Biljon ([email protected]) Chronic kidney disease (CKD) is not a Multicystic dysplastic kidney indefinitely as they may have subclinical priority on the health agenda in South (MCDK) evidence of defects in the solitary kidney Africa, and this is particularly true with A MCDK is estimated to occur in and have an increased risk of developing regard to children. Infectious diseases like approximately 1 in 4 000 live births.1 In most hypertension and proteinuria later in life.4 HIV and tuberculosis, respiratory diseases, cases it is discovered by routine antenatal malnutrition and trauma enjoy a far more sonar, which demonstrates a kidney with Posterior urethral valves prominent status as an attention-worthy multiple cysts of varying sizes. The ureter (PUV) (also known as cause of morbidity and mortality. The is atretic and the kidney is non-functional. congenital obstructing reality is that very few children with end- A MCDK is usually accompanied by both posterior urethral membrane stage renal failure will have access to dialysis compensatory hypertrophy and function of (COPUM)) or renal transplantation. It is imperative, the opposite kidney. Bilateral MCDKs are PUV is the most common cause of severe therefore, that all health care professionals incompatible with extrauterine life. obstructive uropathy in children, affecting 1 should be vigilant in identifying children in 5 000 - 8 000 boys.5 It is rarely seen in girls. with underlying kidney disease and institute The reality is that very preventive treatment to slow progression of PUV are of unclear origin. They are thought disease towards end-stage renal failure. few children with end- to be caused by abnormal insertion of the stage renal failure will mesonephric ducts into the cloaca in the Paediatric kidney diseases that clinicians have access to dialysis or place of the normal plicae colliculi, which are likely to come across in clinical practice cause varying degrees of obstruction.6 include several of the common congenital renal transplantation. abnormalities of the kidney and urinary Affected boys with PUV are usually tract (CAKUT) and acute acquired Infants with a MCDK are usually discovered prenatally when maternal disorders presenting with oedema and or asymptomatic. It is rarely associated with ultrasonography reveals bilateral hydro- hypertension, and positive urine findings. hypertension, while in other cases it is nephrosis, a distended bladder which discovered when a work-up is done for an empties poorly and, if obstruction is Common congenital infant with an abdominal mass. A MCDK severe, oligohydramnios. Features of renal abnormalities of the kidney usually involutes with time. If the diagnosis dysplasia, including cystic changes in the and urinary tract (CAKUT) is not made by antenatal sonar, the patient kidneys, are often present. The routine use of antenatal sonar has may at a later stage be thought to have allowed in utero diagnosis of underlying ‘unilateral renal agenesis’. The morbidity and mortality associated CAKUT before clinical presentation. Early with PUV depends on the severity of the diagnosis and appropriate management can Special investigations to exclude associated obstruction and the time of onset during prevent development of complications in abnormalities in the contralateral kidney, foetal development. Detection of PUV before many of these patients. The most commonly like hypodysplasia, PUJO or VUR are 24 weeks’ gestation identifies a high-risk diagnosed CAKUT include a multicystic necessary because they occur in 30 - 51% of group with a 50% mortality risk. Pulmonary dysplastic kidney (MCDK), vesico-ureteric patients with a MCDK.2 There is no evidence hypoplasia caused by oligohydramnios is reflux (VUR) and obstructive uropathy due that a MCDK is associated with a risk of the most common cause of death in the first to posterior urethral valves (PUV) or pelvo- malignancy.3 All patients with a solitary few hours after birth, while renal dysplasia, ureteric junction obstruction (PUJO). functioning kidney should be followed up which is a consequence of the high urinary February 2012 Vol.30 No.2 CME 49 Paediatric renal conditions tract pressures, results in irreversible sometimes called ‘prune belly syndrome’ The skin of the anterior abdominal wall is chronic renal failure. (Fig. 2). It is characterised by a triad of wrinkled, thin and lax, which accounts for • deficient abdominal musculature the prune-like appearance and the name of Prenatal bladder decompression by vesico- • megacystis and megaureter the syndrome. The ureters are dilated and amniotic shunt placement has been attempted, • cryptorchidism (undescended testes). tortuous. Variable degrees of renal dysplasia but evidence of clinical benefit is lacking.7 occur, ranging from severe dysplasia to mild cystic dysplasia. The bladder is enlarged and Infants with a MCDK are the prostatic urethra is dilated. Urethral obstruction is an associated finding reported usually asymptomatic. in 0 - 100% of patients. Spontaneous decompression of the urinary The diagnosis of PUV is confirmed by a tract following the development of unilateral voiding cysto-urethrogram (VCU) (Figs 3a VUR may act as a pressure vent – which and 3b). leads to ipsilateral renal dysplasia but allows development of better renal function in the contralateral kidney (VURD syndrome).8 Clinical features of PUV Neonates may present with: • Potter facies (see Fig. 1) • acute respiratory distress and spontaneous pneumothorax Fig 2(a). Infant with prune belly syndrome • clubbed feet and contractures of the hips showing wrinkled skin of the abdominal wall. • urinary ascites • acute renal failure − often associated with gram-negative septicaemia • prolonged jaundice due to urinary tract Fig. 3(a). VCU lateral view demonstrating infection (UTI), usually E. coli. posterior urethral valves, a trabeculated bladder with diverticulae and a dilated posterior urethra. Fig. 2(b) Infant with prune belly syndrome Fig. 1. Infant with Potter facies. Note the flat showing severely distended abdomen due to facial profile, beaked nose, small chin and urinary ascites. low-set ears. Special investigations Those with less severe bladder obstruction present later in infancy with: to exclude associated • failure to thrive or stunting abnormalities in the • polyuria contralateral kidney, like • spontaneous unexplained dehydration • recurring UTIs hypodysplasia, PUJO • poor urine stream (dribbling of urine) or VUR are necessary Fig. 3(b). VCU anterior-posterior view • chronic renal failure. because they occur in demonstrating posterior urethral valves, a trabeculated bladder with diverticulae and a Obstructive uropathy may also form part 30 - 51% of patients with dilated posterior urethra. of a syndrome, the Eagle-Barrett syndrome, a MCDK. 50 CME February 2012 Vol.30 No.2 Paediatric renal conditions I II III IV V Fig. 4. International classification system of vesico-ureteric reflux. Management of patients with PUV cases VUR is only discovered when special • The potential benefit of prophylactic • Neonates with PUV who have acute investigations are done following a UTI in antibiotics in children with grades IV and respiratory distress may benefit from a child. V VUR associated with renal impairment ventilatory support, but the majority die is currently being investigated.10 due to pulmonary hypoplasia. In most instances, VUR is an inherited • In children with VUR who develop fever, • Temporary drainage of the bladder can abnormality that resolves over time. The empiric antibiotic treatment should be be achieved with a suprapubic bladder rate of resolution depends on several started promptly after sterile urine culture catheter until valve ablation can be done variables, including the age of the patient at has been done and before the results of at a later stage when the infant is stable. presentation and the grade of reflux. Lower culture and sensitivity are available. • Follow-up ultrasonography should degrees of VUR are associated with high • Early and effective antibiotic treatment be done to monitor improvement of spontaneous resolution rate as the child has been shown to be the main preventive hydronephrosis. Improving hydro- grows older. strategy to limit the risk for development nephrosis without corresponding of a new renal scar. decline of serum creatinine suggests that PUV is the most • There is no conclusive evidence that severe renal dysplasia is present. ureteric reimplantation improves the • Cutaneous vesicostomy is sometimes common cause of severe long-term outcome of children with VUR performed for those infants with obstructive uropathy in compared with conservative treatment. advanced renal failure,

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