Congenital solitary kidney: a review of 74 cases

Unilateral renal agenesis: a systematic review on associated anomalies and renal injury

BACKGROUND

Unilateral renal agenesis (URA) is associated with other congenital anomalies of the kidney and urinary tract (CAKUT) and extra-renal anomalies. However, the reported prevalences of these anomalies are highly variable. We estimated the prevalence of associated CAKUT and extra-renal anomalies in patients with URA. Furthermore, we determined the prevalence of renal injury in URA patients.

METHODS

We conducted a systematic review of English and non-English articles using PubMed and Embase.com. Included studies reported at least one of the following items: incidence of URA, gender, side of URA, prenatal diagnosis, performance of micturating cystourethrogram, associated CAKUT, urinary tract infection or extra-renal anomalies. Studies that described a mean/median glomerular filtration rate (GFR) and proportions of patients with hypertension, micro-albuminuria or a decreased GFR were also included.

RESULTS

Analyses were based on 43 included studies (total number of patients: 2684, 63% male). The general incidence of URA was 1 in ∼2000. Associated CAKUT were identified in 32% of patients, of which vesicoureteral reflux was most frequently identified (24% of patients). Extra-renal anomalies were found in 31% of patients. Hypertension could be identified in 16% of patients, whereas 21% of patients had micro-albuminuria. Ten per cent of patients had a GFR<60 mL/min/1.73 m2;.

CONCLUSIONS

These aggregate results provide insight in the prevalence of associated anomalies and renal injury in patients with URA. Our systematic review implicates that URA is not a harmless malformation by definition. Therefore, we emphasize the need for clinical follow-up in URA patients starting at birth.

Yo-yo reflux in an incomplete duplex system causing severe hydronephrosis in a patient with contralateral renal agenesis

This is a report of a case of a 26-year-old patient suffering from progressive renal insufficiency with a neurogenic bladder disorder due to a lipomyelomeningocele. She had renal agenesis on the left side and grade III hydronephrosis of both segments of a right duplex kidney with a bifid ureter joining further distal to the kidney. Both ureters were dilated. The cause was found to be a yo-yo reflux between the two halves of the kidney. Following bladder augmentation and pyelopyelostomy, renal insufficiency improved to stage III and has now been stable for four years. Due to the contralateral renal agenesis, the case is a unique illustration of the functional effect of the yo-yo reflux and pyelopyelostomy.

Associated anomalies in children with congenital solitary functioning kidney

Congenital solitary functioning kidney (CSFK) is a relatively common renal malformation and in children is frequently complicated by anomalies of the ipsilateral genital organs and occasionally by anomalies of other organs. The aim of this study was to determine the incidence of associated urological, cardiac, gastrointestinal, hematological, neurological, skeletal, and other congenital malformations in children with CSFK. We retrospectively reviewed 87 consecutive cases of CSFK diagnosed at our hospital between 1995 and 2003. There were 45 boys and 42 girls, whose ages at diagnosis ranged from newborn to 16 years (mean 4.67+/-4.48 years). In all patients, CSFK was diagnosed by abdominal ultrasound and confirmed by radionuclide studies. In 46 patients (53%) the left kidney was absent, and in 41 patients (47%) the right kidney was absent. Overall associated anomalies were detected in 52 of the 87 children (60%) with CSFK. Urological anomalies were most common, with an incidence of 37% (32/87). Nonurological anomalies were detected in 38 children (44%) with CSFK; these included cardiac anomalies in 13, gastrointestinal anomalies in eight, hematological anomalies in five, neurological anomalies in three, and other organ anomalies in nine. In our study, more than half of the patients with CSFK had associated anomalies. For this reason we recommend abdominal ultrasound and voiding cystourethrogram for early recognition of urological anomalies and a careful physical examination for other organ anomalies in patients with CSFK.

Unilateral nephrectomy and progression of renal failure

Extensive ablation of renal mass in experimental animals leads to progressive glomerulosclerosis and chronic renal failure (CRF). Clinical studies are far from answering the question whether patients with reduced renal mass are at risk of developing progressive CRF. The aim of our study was to examine the morphological and functional aspects of the remnant kidney in a group of patients who underwent unilateral nephrectomy for renal tuberculosis: 313 patients (161 M, 152 F) mean age 57.2 +/- 10.7, were examined after a period ranging from 13.56 to 591.2 months. All patients were on ad libitum diet. Hypertension was found in 34.19% of the patients; SBP was 155.29 +/- 19.9 mmHg and DBP was 92.74 +/- 13.07 mmHg. Estimation of renal size performed by ultrasound scanner gave the following results: length 116.78 +/- 8.99 mm; width 58.24 +/- 7.21 mm; thickness 17.88 +/- 1.96 mm. Kidney function assessed by serum creatinine levels showed a mean level of 1.28 +/- 0.53 mg%. Forty-two patients (13.41%) had serum levels > 1.5 mg% but 18 of them had nonconcomitant systemic or renal involvement. Microalbuminuria determined by RIA assay was found in 50.5% of the patients. In our group of patients renal functional impairment was low and hyperfiltration expressed as microalbuminuria does not appear to be a primary factor in the progression of renal failure.

Renal function after tumor enucleation in a solitary kidney

Whether extensive ablation of renal mass in humans leads to progressive glomerulosclerosis, proteinuria, and hypertension, as it does in animal models, is a matter of controversy. We have studied kidney function in six patients who underwent enucleation of a renal cell carcinoma in a solitary kidney. Four patients had previously had a nephrectomy. The two others each had one atrophic, nonfunctioning kidney. Serum creatinine levels before surgery were within the normal range (mean, 99.9 mumol/L [1.13 mg/dL]). Two weeks after tumor enucleation, creatinine levels were significantly higher than the preoperative values (mean, 124.6 mumol/L [1.41 mg/dL]). The follow-up period varied from 10 to 23 months. In all patients, kidney function improved during the following months. Serum creatinine levels nearly reached preoperative values in all patients (mean, 105.2 mumol/L [1.19 mg/dL]). None of the patients showed a progressive deterioration in renal function or proteinuria. We found a modest increase in blood pressure in two patients who had been normotensive before surgery. In conclusion, tumor enucleation in a solitary kidney did not cause significant renal injury to the remnant kidneys in our patients, at least in the short term.

Do glomerular hemodynamic adaptations influence the progression of human renal disease?

Although experiments in the rat suggest that glomerular hemodynamic alterations following a reduction of renal mass may be implicated in the progression of chronic renal failure, we argue that the deleterious effects of similar adaptations in human renal disease are unproven. In the otherwise normal solitary kidney the supranormal glomerular filtration rate (GFR) remains stable over the longterm, and in early diabetic nephropathy which is also accompanied by hyperfiltration, renal deterioration cannot be dissociated from a rise in systemic blood pressure. In patients with miscellaneous renal diseases and a depressed basal GFR there is indirect evidence that hyperfiltration might occur in some of the remnant glomeruli. However, at present there is little conclusive evidence to indicate that therapies which might normalize glomerular hemodynamics, e.g., dietary protein restriction, have any effect on progression of renal disease, or that angiotensin converting-enzyme inhibitors, which lower glomerular capillary pressure, have any advantage over other antihypertensive agents which are equally efficacious in lowering systemic blood pressure.

The solitary kidney: a model of chronic hyperfiltration in humans

Reduction of renal mass (11/12) in rats leads to progressive azotemia, proteinuria, and hypertension. Less extensive renal ablation resulting from uninephrectomy also accelerates the progression of focal glomerulosclerosis (FGS) induced by experimental diabetes, renal irradiation, aminonucleoside nephrosis, or aging. The consequence of the absence of one kidney in man are examined in three different clinical situations. Unilateral renal agenesis seems to predispose to the development of FGS, but most reports include isolated cases and the true incidence of FGS is not known. The solitary kidney following uninephrectomy for acquired unilateral disease undergoes a compensatory rise in glomerular filtration rate (GFR) that remains stable for several decades. Finally, kidney donors followed for over 2 decades show unimpaired GFR, elevated at 70% to 80% of the normal (two-kidney) GFR. Some donors develop mild, nonprogressive proteinuria. Their incidence of hypertension matches that in the control population. Thus, hyperfiltration secondary to 50% reduction of renal mass in humans does not lead to loss of function of the remaining parenchyma.

Multicystic dysplastic kidney: is nephrectomy still appropriate?

We analyzed 25 cases of multicystic kidney to assess the impact of prenatal diagnosis on the management of this condition. The incidence of unilateral multicystic kidney was 1 in 4,300 live births. Of the 23 children with unilateral multicystic kidneys only 3 (13 per cent) had a readily palpable lesion. These findings suggest that multicystic kidney is a more common renal anomaly than was previously recognized and that the majority of cases remained undiagnosed before the advent of prenatal diagnosis. Ultrasound re-evaluation in 11 children suggests that the natural history of multicystic kidneys is towards spontaneous involution. Two kidneys were not identifiable by followup ultrasound. Hypertension and malignancy complicating multicystic kidney are reported infrequently. The literature on hypertension does not generally support the view that multicystic kidney poses a significant risk of hypertension in later childhood or adult life. We believe that the routine removal of multicystic kidneys in infancy is no longer appropriate.

Percutaneous intervention in the solitary kidney

The solitary kidney, either after nephrectomy or on a congenital basis, may be impaired by infection, stones, obstruction, and trauma. Because of the possibility of further renal compromise by damage of the remaining nephron units, there is reluctance to utilize percutaneous techniques in cases of solitary kidney, and surgery is often used as an alternative. We report 15 cases of solitary kidney in which interventional radiologic techniques (i.e., percutaneous nephrostomy, ureteral stenting, ureteral dilatation, and stone extraction) were attempted for the preservation of renal function, either as a permanent solution or as a temporizing maneuver prior to definitive therapy. In each case, these goals were achieved and there were no complications.

The child with solitary hydronephrotic kidney

The child with solitary hydronephrotic kidney has a prognosis different from that of the child with hydronephrosis and a normal contralateral kidney. We have reviewed a decade of experience with 31 children with solitary hydronephrotic kidney and have identified characteristics that point to either a favorable or unfavorable prognosis in these children.

Solitary pelvic kidney and neuroblastoma in a child

We describe a case of a solitary pelvic kidney coexisting with adrenal and pelvic neuroblastoma in a child with multiple malformations, including microcephaly, hypertelorism, aortic coarctation and a bifid uterus. The association of a solitary kidney and neuroblastoma has not been reported previously.