Posterior urethral valves: Metabolic consequences in a cohort of patients.

BACKGROUND: Despite the improvements in diagnosis and management of posterior urethral valves (PUVs), about one third of patients develop chronic kidney disease (CKD). Children with PUVs might have abnormal calcium, phosphorus, vitamin D and parathyroid hormone levels, which could affect their bone growth and overall health. OBJECTIVE: The aim was to determine the relationship between kidney function, vitamin D deficiency and secondary hyperparathyroidism in children with PUVs. PATIENTS AND METHODS: Sixty-four children with PUVs were followed for a period of 3.64 ± 2.50 years after their initial presentation and management. Their laboratory parameters were compared with 20 age-, gender- and race-matched children in a control group, including: serum calcium, phosphorus, intact parathyroid hormone (iPTH), 25-hydroxyvitamin D levels, and kidney function. RESULTS: Children with PUVs had significantly lower estimated kidney function (P = 0.006) and vitamin D levels (P < 0.001) and higher iPTH levels (P = 0.042). There were no significant between-group differences in serum calcium, phosphorus, alkaline phosphatase, sodium, potassium, and bicarbonate levels. There was a strong correlation between the degree of vitamin D deficiency and hyperparathyroidism and the degree of kidney dysfunction (r = 0.52 and -0.52, respectively) in the PUV group. On a multivariate analysis, the kidney dysfunction was the only independent predictor of vitamin D deficiency (ρ = 0.271, P < 0.001), while kidney dysfunction, serum calcium and alkaline phosphatase were independent predictors for hyperparathyroidism (ρ = 0.925, P<0.001, ρ = 0.933, P<0.001 and ρ = 0.913, P < 0.001, respectively). DISCUSSION: The prevalence of CKD in children with PUVs ranges from 30 to 60%. Patients with CKD are more likely to have vitamin D deficiency and display more-prominent hyperparathyroidism. Compared with a control group with normal kidney function, the present cohort had lower 25-hydroxyvitamin D and higher iPTH serum levels. Abnormal kidney function was a major predictor for both serum levels. In this cohort, there were no significant differences in serum calcium and phosphorus between children with PUVs and the control group, and also between those with and without CKD. On the contrary, vitamin D level decreased early in the disease and progressively declined thereafter, while iPTH was the opposite. These findings were comparable to previous studies. This study had some limitations because it was a single center cross-sectional non-randomized study. However, the findings in this study can be extrapolated to children with PUVs and CKD from other origins because the unit is considered as a referral center in the Middle East region. CONCLUSION: Abnormal kidney function, vitamin D deficiency, and secondary hyperparathyroidism are prevalent in children with PUVs. Kidney function is the main determinant of vitamin D and parathyroid hormone levels. Efforts should be directed toward managing CKD, and controlling vitamin D deficiency and hyperparathyroidism in children after ablation of PUV.

Multicystic dysplastic kidney: Impact of imaging modality selection on the initial management and prognosis.

OBJECTIVE: To evaluate the impact of imaging modalities on the evaluation and prognosis of children with multicystic dysplastic kidney (MCDK) disease. PATIENTS AND METHODS: A retrospective analysis of all children with MCDK diagnosed from 2004 until 2012 was performed. The study included 63 patients for whom all postnatal imaging modalities were available: renal bladder ultrasound (RBUS), dimercaptosuccinic acid scan (DMSA) and voiding cystourethrogram (VCUG). Cases with major congenital abnormalities or incomplete data were excluded. Abnormalities in the contralateral kidney and the fate of MCDK were also addressed. RESULTS: At diagnosis, the average age was four-and-a-half months. The majority of cases were detected antenatally (87%). Postnatal RBUS and DMSA scans established the diagnosis of MCDK in 92% and 98% of patients, respectively. DMSA showed photopenic areas in the contralateral kidneys in 10% of patients; all of them had hydronephrosis and were confirmed to have vesicoureteral reflux (VUR). Contralateral VUR was detected in 16 patients; 63% of them had hydronephrosis. After a mean follow-up of three-and-a-half years, involution occurred in 62% of patients and the involution rate was inversely proportional to the initial size. CONCLUSIONS: The classical appearance of MCDK on RBUS was sufficient to establish the diagnosis in most patients. DMSA scan was more accurate in confirming the diagnosis and evaluating the contralateral kidney. Selective screening for VUR in patients with contralateral hydronephrotic kidney should be considered.