title: Posterior urethral valves: Metabolic consequences in a cohort of patients.
abstract: 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.
  
  
  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).
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Pediatric Urology, Prince Sultan Military Medical City, Riyadh, Saudi Arabia; Urology and Nephrology Center, Mansoura University, Mansoura, Egypt. Electronic address: o_sarhan2004@yahoo.com.
authors.forename: O
authors.initials: O
authors.lastname: Sarhan
authors.affiliation: Division of Pediatric Urology, Prince Sultan Military Medical City, Riyadh, Saudi Arabia. Electronic address: drziad@hotmail.com.
authors.forename: Z
authors.initials: Z
authors.lastname: Nakshabandi
authors.affiliation: Division of Pediatric Urology, Prince Sultan Military Medical City, Riyadh, Saudi Arabia. Electronic address: alghanbar@yahoo.com.
authors.forename: M
authors.initials: M
authors.lastname: Alghanbar
authors.affiliation: Division of Pediatric Urology, Prince Sultan Military Medical City, Riyadh, Saudi Arabia. Electronic address: alotay99@hotmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Alotay
authors.affiliation: Biochemistry Department, Mansoura University, Mansoura, Egypt. Electronic address: emyosh@yahoo.com.
authors.forename: I
authors.initials: I
authors.lastname: Sherif
authors.affiliation: Division of Nephrology, University of Kentucky, Lexington, KY, USA. Electronic address: charlesmwhitehead@gmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Whitehead
authors.affiliation: Urology and Nephrology Center, Mansoura University, Mansoura, Egypt; Division of Nephrology, University of Kentucky, Lexington, KY, USA. Electronic address: amr.elhusseini.moh@uky.edu.
authors.forename: A
authors.initials: A
authors.lastname: El-Husseini
mesh_terms: D001851:Bone Diseases, Metabolic / Q000453:epidemiology / Q000209:etiology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000453:epidemiology / Q000209:etiology* / Q000378:metabolism; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D015995:Prevalence; D012189:Retrospective Studies; D012529:Saudi Arabia / Q000453:epidemiology; D013997:Time Factors; D014521:Urethra / Q000002:abnormalities*; D014524:Urethral Obstruction / Q000150:complications* / Q000151:congenital / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology / Q000209:etiology* / Q000378:metabolism
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium
keywords: Children; Chronic kidney disease-mineral bone disorder; Posterior urethral valves; Secondary hyperparathyroidism; Vitamin D deficiency