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Editor,—Webb et al justify their policy of performing nephrectomy in healthy infants with prenatally detected multicystic dysplastic kidney (MCDK) on the basis of their findings in three children and their interpretation of the literature.1 Paediatricians may wish to scrutinise the methodology and conclusions of this paper more closely before referring asymptomatic infants for ‘prophylactic’ nephrectomy. On the evidence provided the diagnosis of hypertension in their first two patients has not been conclusively proved. Furthermore, it is difficult to see how the renal pathology in their third patient can be attributed to MCDK in the absence of cysts and, more importantly, ureteric atresia.
Making a diagnosis of hypertension in children is problematic—indeed obtaining reliable reproducible blood pressure readings in fractious infants is very difficult. The measurement of peripheral plasma renin activity, which was performed in these children, is a relatively poor guide to the aetiology of hypertension. A credible diagnosis requires selective renal vein renin sampling.
The role of echocardiography in the diagnosis and assessment of mild or moderate hypertension in childhood has yet to be validated. The authors have not identified the source of the normal ranges quoted—an important consideration since different studies have yielded different ‘normal’ values for the parameters quoted and the ‘normal’ range has often been derived from a limited number of individuals in different age groups.
In their third patient, a hypertensive girl of 14, retrograde pyelography is said to have revealed ‘remnant renal tissue in the right loin’. Atresia of the pelviureteric junction or proximal ureter is a characteristic feature of MCDK which, on retrograde pyelography, is associated with the distinctive finding of a blind ending ureter. In this case the flow of contrast across a patent ureter into a remnant of the collecting system, effectively excludes the diagnosis of MCDK.
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