Introduction: Respiratory syncytial virus (RSV) is one of the most common causes of acute respiratory infections in all age groups especially under two years. The aim of this study was to investigate the frequency and clinical features of RSV in hospitalized children under two years of age with the diagnosis of lower respiratory tract infections (LRTI) in our region. Methodology: Between September 2011-May 2013, hospitalized children aged 0-2 years with the diagnosis of viral LRTI, in which nasopharengeal secretions were tested for the presence of the RSV antigen, were included in this prospective study. Results: Among the total of 361 hospitalized children who were investigated for RSV antigen, 138 (38%) were female and 223 (62%) were male. The mean age of the group was 5,7±5,1 months (0-24 months). RSV antigen in nasopharyngeal secretions was positive in 68 (19%) of 361 patients. RSV infection was detected significantly higher in December and January (p = 0.003). RSV positivity was significantly higher in patients aged under 6 months (p=0.01), with shorter duration of breastfeeding (p = 0.02), low socioeconomic status (p = 0.02), and also born with spontaneous vaginal delivery (p = 0.007). In RSV(+) LRTI group, children were associated with severe disease than RSV (-LRTI group (p = 0.014). Conclusions: Since there is lack of data investigating the frequency and the risk factors of RSV respiratory infections in our region, the present study is important for providing new data. Furthermore, this is the second study investigating the correlation between RSV positivity and meteorological conditions in Turkey.

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is an X-linked disease caused by activating mutations in the arginine vasopressin (AVP) receptor-2 ( AVPR2 ) gene. Affected patients excrete concentrated urine despite very low levels of AVP, and consequently develop euvolemic hyponatremia. Due to its low frequency, patients may be misdiagnosed and treated incorrectly. We report two related male infants with NSIAD that was initially confused with hyporeninemic hypoaldosteronism (HH). First, a 2-month-old male presented with hyponatremia, low plasma osmolality, relatively high urine osmolality, and low plasma renin-aldosterone levels. These clinical and laboratory findings were compatible with syndrome of inappropriate antidiuretic hormone (ADH) secretion without apparent cause. Consequently, fludrocortisone was initiated with a presumptive diagnosis of HH. While correcting hyponatremia, fludrocortisone treatment led to hypertension and was discontinued promptly. The second patient, aged one year, was admitted with a history of oligohydramnios, had been hospitalized four times due to hyponatremia since birth, and had a diagnosis of epilepsy. Similarly, the second infant had clinical and laboratory findings compatible with syndrome of inappropriate ADH secretion with no apparent cause. Fluid restriction normalized his serum sodium despite the plasma AVP level being undetectable. In both infants, AVPR2 gene analysis revealed a known mutation (c.409C>T; p.R137C) and confirmed the diagnosis of NSIAD. In conclusion, NSIAD should be considered in all patients with unexplained euvolemic hyponatremia despite high urine osmolality. If NSAID is not considered, the plasma reninaldosterone profile can be confused with HH, especially in infants.

Objective: Guidelines on congenital hypothyroidism (CH) recommend that genetic testing should aim to improve diagnosis, treatment or prognosis, but it is unclear which patients would benefit most from genetic investigation. We aimed to investigate the genetic etiology of transient (TCH) and permanent CH (PCH) in a well-characterized cohort, and thereby to evaluate the impact of genetic testing on the management and prognosis of children with CH. Methods: A total of 48 CH patients with normal, goitrous (n:5) or hypoplastic thyroid (n:5) were studied by high-throughput sequencing using a custom-designed 23-gene panel. Patients initially categorized as TCH (n:15), PCH (n:26) and persistent hyperthyrotropinemia (PHT, n:7) were re-evaluated after genetic testing. Results: Re-evaluation based on genetic testing changed the initial diagnoses from PCH to PHT (n:2) or TCH (n:3), and from PHT to TCH (n:5), which resulted in a final distribution of TCH (n:23), PCH (n:21) and PHT (n:4). Genetic analysis also allowed us to discontinue treatment in five patients with monoallelic TSHR or DUOX2, or no pathogenic variants. Main reasons for changes in diagnosis and treatment were the detection of monoallelic TSHR variants, and the misdiagnosis of thyroid hypoplasia on neonatal ultrasound in low birthweight infants. A total of 41 (35 different, 15 novel) variants were detected in 65% (n:31) of the cohort. These variants, which most frequently affected TG, TSHR and DUOX2, explained the genetic etiology in 46% (n:22) of the patients. Molecular diagnosis rate was significantly higher in patients with PCH (57%, n:12) than TCH (26%, n:6). Conclusions: Genetic testing can change diagnosis and treatment decisions in a small proportion of children with CH, but the resulting benefit may outweigh the burden of lifelong follow-up and treatment.