| Abstract|| |
Oligomeganephronia represents a distinct subgroup of renal hypoplasia in which there is a marked reduction in the number of nephrons with hypertrophy of those that are present. It can only be recognised on renal biopsy. We describe a 14-year-old boy who presents with a history of dysuria and some blood in his pants. Urinalysis showed no hematuria but persistent heavy proteinuria. The size of the kidneys on ultrasound was between -1 to -2 SD for height (right 9.3; left 9.6cm) and both kidneys showed a diffuse increase in echogenicity. The pathological features were diagnostic with a reduced number of greatly enlarged glomeruli indicating oligomeganephronia. No focal segmental glomerulosclerosis was identified but there was subcapsular fibrosis. Hyperfiltration in the small number of nephrons initially maintains the glomerular filtration rate at an acceptable level but by adolescence these children typically have progressive proteinuria, glomerulosclerosis and renal failure.
Keywords: Oligomeganephronia, Adolescence, Renal failure.
|How to cite this article:|
Abdelraheem M, Watson AR, McCulloch TA. Oligomeganephronia: An Unexpected Cause of Chronic Renal Failure. Saudi J Kidney Dis Transpl 2004;15:53-6
|How to cite this URL:|
Abdelraheem M, Watson AR, McCulloch TA. Oligomeganephronia: An Unexpected Cause of Chronic Renal Failure. Saudi J Kidney Dis Transpl [serial online] 2004 [cited 2020 Jun 6];15:53-6. Available from: http://www.sjkdt.org/text.asp?2004/15/1/53/32966
| Introduction|| |
Oligomeganephronia represents a distinct subgroup of renal hypoplasia in which there is a marked reduction in the number of nephrons with hypertrophy of those that are present. It can only be recognised on renal biopsy. We describe an adolescent who was investigated for persistent proteinuria and moderate chronic renal failure after he had presented with balanitis. Renal biopsy revealed the diagnosis.
| Case Report|| |
A 14 year old boy was referred by his general practitioner with a history of dysuria and some blood in his pants. There was no history of other episodes of macroscopic hematuria or urinary tract symptoms. He received local treatment for a diagnosis of balanitis but his urinalysis showed persistent proteinuria +++ and an elevated plasma creatinine of 131µmol/l.
There was no family history of renal disease apart from one kidney stone in the father. Our patient was a non-identical twin with no neonatal problems. He was well grown with a height on the 93rd centile and weight on the 50th centile. His blood pressure was 110/70 mmHg and there were no abdominal masses.
Urinalysis showed no hematuria but persistent proteinuria with an early morning protein: creatinine ratio of 220mg/mmol (normal < 20).  The measured glomerular filtration rate (GFR) by Cr 51 EDTA was 49ml/min/1.73m 2 (-3.7 SD from the normal mean).
The kidneys size on ultrasound was between -1 to -2 SD for height (right 9.3; left 9.6cm) and both kidneys showed a diffuse increase in echogenicity. On the right, there were a few small parenchymal cysts and on the left some suggestion of cortical loss at the upper pole. The Mag 3 scan showed equal perfusion of both kidneys with no evidence of vesicoureteric reflux on the indirect micturating cystogram.
In view of the uncertainty of the diagnosis a percutaneous renal biopsy under sedation as a day case was performed.  The pathological features were diagnostic with a reduced number of greatly enlarged glomeruli indicating oligomeganephronia [Figure - 1]. No focal segmental glomerulosclerosis was identified but there was subcapsular fibrosis.
| Discussion|| |
Oligomeganephronia was first described by Habib et al  in 1962 as a type of renal hypoplasia resulting from a qualitative defect of the renal parenchyma with a reduced number of nephrons. The condition differs histopathologically from simple hypoplasia in which there is a reduced renal mass with normal size nephrons. 
The exact incidence of oligomeganephronia is difficult to determine due mainly to the fact that few children or young adults with hypoplastic kidneys undergo renal biopsy. One can imagine that if our patient had not developed balanitis with hematuria then the proteinuria would not have been detected and he might not have presented until adult life with severe chronic renal failure. It is well recognised that an exact diagnosis is not defined in many adult patients with ESRD in whom small kidneys are found but biopsy not undertaken.
Congenital oligomeganephronia can be caused by genetic (racial) predisposition, for instance in Australian Aborigines. The latter have a high incidence of oligomeganephronia, which leads to focal segmental glomerulosclerosis and end-stage renal failure (ESRF).  Oligomeganephronia has also been described in children with hearing and ocular problems, mental retardation and limb abnormalities.  In a case report of monozygotic twins who were non-concordant for oligomeganephronia, the authors postulated artery-vein placental shunting as a possible pathogenic mechanism. It is interesting to note that our patient was also a twin pregnancy and we wondered initially whether twin-to-twin transfusion was the underlying cause as renal dysplasia is a recognised feature. 
Patients with oligomeganephronia were studied more extensively when the concept of a reduced nephron mass leading to progressive glomerulosclerosis was proposed in the 1970s. A severely reduced nephron number eventually leads to glomerulosclerosis and ESRF in adolescents. ,, Hyperfiltration in the small number of nephrons initially maintains the GFR at an acceptable level but by adolescence these children typically have progressive proteinuria, glomerulosclerosis and renal failure. 
| References|| |
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Alan R Watson
Consultant Pediatric Nephrologist, Children & Young People's Kidney Unit, Nottingham City Hospital NHS Trust, Hucknall Road, Nottingham NG5 1PB
[Figure - 1]