Cengiz Candan

Cardiovascular Phenotypes in Children with CKD: The 4C Study

BACKGROUND AND OBJECTIVES Cardiovascular disease is the most important comorbidity affecting long-term survival in children with CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The Cardiovascular Comorbidity in Children with CKD Study is a multicenter, prospective, observational study in children ages 6-17 years old with initial GFR of 10-60 ml/min per 1.73 m2. The cardiovascular status is monitored annually, and subclinical cardiovascular disease is assessed by noninvasive measurements of surrogate markers, including the left ventricular mass index, carotid intima-media thickness, and central pulse wave velocity. We here report baseline data at study entry and an explorative analysis of variables associated with surrogate markers. RESULTS A total of 737 patients were screened from October of 2009 to August of 2011 in 55 centers in 12 European countries, and baseline data were analyzed in 688 patients. Sixty-four percent had congenital anomalies of the kidney and urinary tract; 26.1% of children had uncontrolled hypertension (24-hour ambulatory BP monitoring; n=545), and the prevalence increased from 24.4% in CKD stage 3 to 47.4% in CKD stage 5. The prevalence of left ventricular hypertrophy was higher with each CKD stage, from 10.6% in CKD stage 3a to 48% in CKD stage 5. Carotid intima-media thickness was elevated in 41.6%, with only 10.8% of patients displaying measurements below the 50th percentile. Pulse wave velocity was increased in 20.1%. The office systolic BP SD score was the single independent factor significantly associated with all surrogate markers of cardiovascular disease. The intermediate end point score (derived from the number of surrogate marker measurements >95th percentile) was independently associated with a diagnosis of congenital anomalies of the kidney and urinary tract, time since diagnosis of CKD, body mass index, office systolic BP, serum phosphorus, and the hemoglobin level. CONCLUSIONS The baseline data of this large pediatric cohort show that surrogate markers for cardiovascular disease are closely associated with systolic hypertension and stage of CKD.

Mutations in ANKS6 Cause a Nephronophthisis-Like Phenotype with ESRD

Nephronophthisis (NPHP) is one of the most common genetic causes of CKD; however, the underlying genetic abnormalities have been established in <50% of patients. We performed genome-wide analysis followed by targeted resequencing in a Turkish consanguineous multiplex family and identified a canonic splice site mutation in ANKS6 associated with an NPHP-like phenotype. Furthermore, we identified four additional ANKS6 variants in a cohort of 56 unrelated patients diagnosed with CKD due to nephronophthisis, chronic GN, interstitial nephritis, or unknown etiology. Immunohistochemistry in human embryonic kidney tissue demonstrated that the expression patterns of ANKS6 change substantially during development. Furthermore, we detected increased levels of both total and active β-catenin in precystic tubuli in Han:SPRD Cy/+ rats. Overall, these data indicate the importance of ANKS6 in human kidney development and suggest a mechanism by which mutations in ANKS6 may contribute to an NPHP-like phenotype in humans.

Markers of bone metabolism are affected by renal function and growth hormone therapy in children with chronic kidney disease.

Objectives The extent and relevance of altered bone metabolism for statural growth in children with chronic kidney disease is controversial. We analyzed the impact of renal dysfunction and recombinant growth hormone therapy on a panel of serum markers of bone metabolism in a large pediatric chronic kidney disease cohort. Methods Bone alkaline phosphatase (BAP), tartrate-resistant acid phosphatase 5b (TRAP5b), sclerostin and C-terminal FGF-23 (cFGF23) normalized for age and sex were analyzed in 556 children aged 6–18 years with an estimated glomerular filtration rate (eGFR) of 10–60 ml/min/1.73m2. 41 children receiving recombinant growth hormone therapy were compared to an untreated matched control group. Results Standardized levels of BAP, TRAP5b and cFGF-23 were increased whereas sclerostin was reduced. BAP was correlated positively and cFGF-23 inversely with eGFR. Intact serum parathormone was an independent positive predictor of BAP and TRAP5b and negatively associated with sclerostin. BAP and TRAP5B were negatively affected by increased C-reactive protein levels. In children receiving recombinant growth hormone, BAP was higher and TRAP5b lower than in untreated controls. Sclerostin levels were in the normal range and higher than in untreated controls. Serum sclerostin and cFGF-23 independently predicted height standard deviation score, and BAP and TRAP5b the prospective change in height standard deviation score. Conclusion Markers of bone metabolism indicate a high-bone turnover state in children with chronic kidney disease. Growth hormone induces an osteoanabolic pattern and normalizes osteocyte activity. The osteocyte markers cFGF23 and sclerostin are associated with standardized height, and the markers of bone turnover predict height velocity.

Follow-up results of patients with ADCK4 mutations and the efficacy of CoQ10 treatment

BackgroundADCK4-related glomerulopathy is an important differential diagnosis in adolescents with steroid-resistant nephrotic syndrome (SRNS) and/or chronic kidney disease (CKD) of unknown origin. We screened adolescent patients to determine the frequency of ADCK4 mutation and the efficacy of early CoQ10 administration.MethodsA total of 146 index patients aged 10–18 years, with newly diagnosed non-nephrotic proteinuria, nephrotic syndrome, or chronic renal failure and end-stage kidney disease (ESKD) of unknown etiology were screened for ADCK4 mutation.ResultsTwenty-eight individuals with bi-allelic mutation from 11 families were identified. Median age at diagnosis was 12.4 (interquartile range [IQR] 8.04–19.7) years. Upon first admission, all patients had albuminuria and 18 had CKD (6 ESKD). Eight were diagnosed either through the screening of family members following index case identification or during genetic investigation of proteinuria in an individual with a history of a transplanted sibling. Median age of these 8 patients was 21.5 (range 4.4–39) years. CoQ10 supplementation was administered following genetic diagnosis. Median estimated glomerular filtration rate (eGFR) just before CoQ10 administration was 140 (IQR 117–155) ml/min/1.73m2, proteinuria was 1,008 (IQR 281–1,567) mg/m2/day. After a median follow-up of 11.5 (range 4–21) months following CoQ10 administration, proteinuria was significantly decreased (median 363 [IQR 175–561] mg/m2/day, P=0.025), whereas eGFR was preserved (median 137 [IQR 113–158] ml/min/1.73m2, P=0.61).ConclusionsADCK4 mutations are one of the most common causes of adolescent-onset albuminuria and/or CKD of unknown etiology in Turkey. CoQ10 supplementation appears efficacious at reducing proteinuria, and may thereby be renoprotective.

Urinary tract infections in children with myelodysplasia in whom clean intermittent catheterization was administered

AIM In this study, it was aimed to evaluate the frequency of significant bacteriuria and antibiotic resistance characteristics in children with myelodysplasia in whom clean intermittent catheterization was administered. MATERIAL AND METHODS The study group was composed of 71 patients with myelodysplasia who were found to have significant bacteriuria (age: 8.20±4.57 years; 39 girls) and the control groups was composed of 49 children who were diagnosed with community-acquired urinary tract infection (age: 7.94±4.17 years; 29 girls). The patient and control groups were evaluated in terms of the microorganisms grown in urinary cultures and antibiotic resistance characteristics. The study approved by the ethics committe (14/02/2012-19/E). RESULTS Growth of Escherichia coli (E. coli) was found with the highest rate in myelodysplasic patients. However, when compared with the control group in terms of microorganism types, an increase in the growth rates of the microorganisms excluding E. coli was observed in the patients with myelodysplasia which was close to the significance limit (p=0.055). When antibiotic resistance properties were examined, a significantly increased resistance against cotrimaxazole was found in the patient group compared to the control group (p=0.001). 84.5% of the patients were using prophylactic antibiotic including mainly co-trimoxazole. A significantly increased co-trimoxazole resistance was also found in the patients who were using prophylactic antibiotic compared to the patients who were not using prophylactic antibiotic (p=0.025). The rate of symptomatic UTI was found to be 21% in the patients with myelodysplasia and a significant increase was found in the complaints of abdominal/side pain and nausea/vomiting as well as fever in these patients compared to the patients with asymptomatic bacteriuria (p=0.029 and p=0.032, respectively). CONCLUSION Our results show that UTI is still a significant problem in patients with myelodysplasia. In addition, they show that use of prophylactic antibiotic may increase the frequency of development of resistance and co-trimoxazole used for this objective is not a good option..

Genetic, Environmental, and Disease-Associated Correlates of Vitamin D Status in Children with CKD

BACKGROUND AND OBJECTIVES Vitamin D deficiency is endemic in children with CKD. We sought to investigate the association of genetic disposition, environmental factors, vitamin D supplementation, and renal function on vitamin D status in children with CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Serum 25-hydroxy-vitamin D, 1,25-dihydroxy-vitamin D, and 24,25-dihydroxy-vitamin D concentrations were measured cross-sectionally in 500 children from 12 European countries with CKD stages 3-5. All patients were participants of the Cardiovascular Comorbidity in Children with Chronic Kidney Disease Study, had CKD stage 3-5, and were age 6-18 years old. Patients were genotyped for single-nucleotide polymorphisms in the genes encoding 25-hydroxylase, vitamin D binding protein, 7-dehydrocholesterol reductase, and 24-hydroxylase. Associations of genetic status, season, local solar radiation, oral vitamin D supplementation, and disease-associated factors with vitamin D status were assessed. RESULTS Two thirds of patients were vitamin D deficient (25-hydroxy-vitamin D <16 ng/ml). 25-Hydroxy-vitamin D concentrations varied with season and were twofold higher in vitamin D-supplemented patients (21.6 [14.1] versus 10.4 [10.1] ng/ml; P<0.001). Glomerulopathy, albuminuria, and girls were associated with lower 25-hydroxy-vitamin D levels. 24,25-dihydroxy-vitamin D levels were closely correlated with 25-hydroxy-vitamin D and 1,25-dihydroxy-vitamin D (r=0.87 and r=0.55; both P<0.001). 24,25-dihydroxy-vitamin D concentrations were higher with higher c-terminal fibroblast growth factor 23 and inversely correlated with intact parathyroid hormone. Whereas 25-hydroxy-vitamin D levels were independent of renal function, 24,25-dihydroxy-vitamin D levels were lower with lower eGFR. Vitamin D deficiency was more prevalent in Turkey than in other European regions independent of supplementation status and disease-related factors. Single-nucleotide polymorphisms in the vitamin D binding protein gene were independently associated with lower 25-hydroxy-vitamin D and higher 24,25-dihydroxy-vitamin D. CONCLUSIONS Disease-related factors and vitamin D supplementation are the main correlates of vitamin D status in children with CKD. Variants in the vitamin D binding protein showed weak associations with the vitamin D status.

Effects of nutritional vitamin D supplementation on markers of bone and mineral metabolism in children with chronic kidney disease

Background We investigated the effects of nutritional vitamin D supplementation on markers of bone and mineral metabolism, i.e. serum levels of fibroblast growth factor 23 (FGF23), Klotho, bone alkaline phosphatase (BAP) and sclerostin, in two cohorts with chronic kidney disease (CKD). Methods In all, 80 vitamin D-deficient children were selected: 40 with mild to moderate CKD from the ERGO study, a randomized trial of ergocalciferol supplementation [estimated glomerular filtration rate (eGFR) 55 mL/min/1.73 m2], and 40 with advanced CKD from the observational Cardiovascular Comorbidity in Children with Chronic Kidney Disease (4C) study (eGFR 24 mL/min/1.73 m2). In each study, vitamin D supplementation was started in 20 children and 20 matched children not receiving vitamin D served as controls. Measures were taken at baseline and after a median period of 8 months. Age- and gender-related standard deviation scores (SDSs) were calculated. Results Before vitamin D supplementation, children in the ERGO study had normal FGF23 (median 0.31 SDS) and BAP (-0.10 SDS) but decreased Klotho and sclerostin (-0.77 and -1.04 SDS, respectively), whereas 4C patients had increased FGF23 (3.87 SDS), BAP (0.78 SDS) and sclerostin (0.76 SDS) but normal Klotho (-0.27 SDS) levels. Vitamin D supplementation further increased FGF23 in 4C but not in ERGO patients. Serum Klotho and sclerostin normalized with vitamin D supplementation in ERGO but remained unchanged in 4C patients. BAP levels were unchanged in all patients. In the total cohort, significant effects of vitamin D supplementation were noted for Klotho at eGFR 40-70 mL/min/1.73 m2. Conclusions Vitamin D supplementation normalized Klotho and sclerostin in children with mild to moderate CKD but further increased FGF23 in advanced CKD.

Çocukluk çağında hipertansiyona yaklaşım Derleme

Cocuklarda hipertansiyonun sikligi eriskinlerden daha azdir Bununla birlikte hipertansiyon pediyatride onemli bir klinik sorundur ve tanim etioloji ve tedavisi eriskinlerden bazi temel yonlerden farklidir Cocuklarda kan basincinin belirlenmesi uygun teknik ve cihazlarin kullanilmasini gerektirir Bazi olgularda tani konulmasi icin yogun arastirmalar zorunludur Tanisal calismalar bireysellestirilmeli ve olasi klinik ipuclari degerlendirilmelidir Hipertansif cocuklarin tedavisi hasta ve aile egitimi nonfarmakolojik onlemler ve antihipertansif ilaclari iceren ayrintili bir yaklasimi gerektirir Bu yazida cocuk ve ergenlerde kan basinci yuksekliginin saptanmasi degerlendirilmesi ve tedavisi gozden gecirilmistir Anahtar Kelimeler: cocuk ergen etioloji hipertansiyon kan basinci tedavi