Is symmetric dimethylarginine a sensitive biomarker of subclinical kidney injury in children born with low birth weight?

OBJECTIVE: The aim of this study was to investigate if Symmetric Dimethylarginine (SDMA) is a sensitive biomarker of renal function and may predict subclinical kidney injury in low birth weight (LBW) children. METHODS: We studied 68 LBW children and 20 children as reference group. An enzyme-linked immunosorbent assay was used to measure serum SDMA and Cystatin C (Cys C). RESULTS: SDMA levels were higher in study groups compared to reference groups. There was a strong correlation between SDMA and Cys C, also SDMA negatively correlated with eGFR. CONCLUSION: Elevated SDMA concentration may play an important role in pathogenesis of chronic kidney disease.

An association between kidney stone composition and urinary metabolic disturbances in children.

OBJECTIVE: To determine kidney stone composition in children and to correlate stone fractions with urinary pH and metabolic urinary risk factors. PATIENTS AND METHODS: We studied 135 pediatric patients with upper urinary tract lithiasis in whom excreted or extracted stones were available for analyses. Composition of stones was analyzed. A 24-hour urine assessment included volume, pH and daily excretions of calcium, oxalate, uric acid, cystine, creatinine, phosphate, magnesium and citrate. RESULTS: Calcium oxalate was the major component of 73% stones, followed by struvite (13%) and calcium phosphate (9%). Uric acid was present in almost half of stones, but in rudimentary amounts. The calcium oxalate content in calculi showed a strong relationship with calciuria, and moderate association with oxaluria, magnesuria and acidification of urine. The percent content of struvite presented reverse and lower correlations with regard to the above parameters. Calcium phosphate stone proportion had low associations with urinary risk factors. CONCLUSIONS: Calciuria, oxaluria, magnesuria and low urine pH exerted the biggest influence on calcium oxalate content in pediatric renal stones. Relationships of urinary risk factors with calculi calcium phosphate content were of unclear significance. Urinary citrate excretion did not significantly correlate with kidney stone composition in children.

Serum copeptin levels in adolescents with primary hypertension.

BACKGROUND: The prevalence of hypertension continues to rise in the pediatric population. In recent years, there has been an increasing amount of reports on serum arginine vasopressin and its derivative, copeptin, in blood pressure control, but its role is still unclear. The objective of this study was to assess serum copeptin in adolescents with essential hypertension. METHODS: The study cohort consisted of 84 subjects (30 girls and 54 boys) aged 11-18 years, divided into two groups: hypertension (HT) - 53 subjects with confirmed primary hypertension and R - reference group - 31 subjects in whom hypertension was excluded on the basis of ambulatory blood pressure monitoring (ABPM) (white-coat hypertension). Serum copeptin concentration was measured using a commercially available enzyme-linked immunosorbent assay kit (USCN). RESULTS: Hypertensive patients had higher serum copeptin levels (median, 267 [Q1-Q3: 151.1-499.7 pg/ml]) than controls (median, 107.3 [Q1-Q3: 36.7-203.4 pg/ml]), (p < 0.01). Statistically significant difference was found both in males and females. In both groups, positive correlations between serum copeptin and uric acid levels (r = 0.31, p < 0.01), albuminuria (r = 0.45, p < 0.01), serum triglycerides (r = 0.3, p < 0.05), body mass index (BMI) standard deviation score (SDS) (r = 0.24, p < 0.05) and 24-h systolic blood pressure (SBP) (r = 0.37, p < 0.01) and diastolic blood pressure (DBP) (r = 0.23, p < 0.05) were found. CONCLUSIONS: In summary, higher serum copeptin levels, a surrogate for arginine vasopressin (AVP) release, are associated not only with systolic and diastolic blood pressure but also with several components of metabolic syndrome including obesity, elevated concentration of triglycerides, albuminuria, and serum uric acid level. However, for the time being, more research is needed in order to confirm the role of serum copeptin as a novel marker of elevated blood pressure and predictor of metabolic syndrome.

Urinary angiotensinogen as a novel marker of obstructive nephropathy in children.

AIM: Obstructive nephropathy due to congenital or acquired urinary tract obstruction is one of the most important causes of chronic renal failure in children. There is a need for identification of new noninvasive urinary biomarkers to provide the clinician with fast, specific and reliable diagnostic and prognostic tool. The aim of the study was to determine whether urinary angiotensinogen (uAGT) may be a useful marker of obstruction in children with hydronephrosis (HN) caused by ureteropelvic junction obstruction (UPJO). METHODS: The study cohort consisted of surgical group (SG): 31 children with severe HN who required surgery; nonsurgical group (NSG): 20 patients with mild HN, and reference group (RG): 19 healthy children. Urinary concentrations of angiotensinogen were measured using immunoenzymatic ELISA commercial kit and were expressed in ng/mg Cre (uAGT/uCre). RESULTS: uAGT/uCre level was higher in SG when compared to NSG (p < 0.01) and healthy participants (SG vs. RG: p < 0.01). The difference between the uAGT/uCre in NSG and RG was not statistically significant (p > 0.05). uAGT/uCre was correlated negatively with differential renal function (r = -0.46; p < 0.01). CONCLUSION: The present pilot study has clearly demonstrated that children with UPJO showed increased uAGT levels, which correlated negatively with differential renal function in radionuclide scan.