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Background Hypothyroxinemia is defined by low levels of thyroxine (T4) despite low or normal levels of thyroid-stimulating hormone (TSH). This study aimed to evaluate the factors associated with transient hypothyroxinemia of prematurity (THOP) in newborns admitted to the neonatal intensive care unit (NICU). Method This is a single center, retrospective, case-control study. Premature newborns, between 24 and 34 weeks of gestation, hospitalised between January 2014–December 2019 in Istanbul University-Cerrahpasa Faculty of Medicine NICU were analyzed through their medical records. Thyroid function tests were routinely performed between the 10th and 20th days of postnatal life and were evaluated according to the gestational age references. Thirty six possible associated factors (prenatal and postnatal parameters, medical treatments, clinical diagnoses and applications in NICU) were searched in the patient group with THOP (n = 71) and the control group with euthyroid prematures (n = 73). The factors for THOP were identified by univariate analysis, followed by multivariate analysis. Results Mean gestational ages of the study and the control groups were 29.7 ± 2.48 and 30.5 ± 2.30 weeks, respectively (p = 0.606). The birth weight, small for gestational age (SGA), intraventricular hemorrhage (IVH), congenital heart disease (CHD) were found to be the possible associated factors for THOP in the univariate analysis and CHD (p = 0.007, odds ratio [OR]:4.9, 95% confidence interval [CI]: 1.5–15.8), BW (p = 0.004, OR:0.999, 95% CI: 0.9–1.0) and SGA (p = 0.010, OR:4.6, 95% CI: 1.4–14.7) were found to be factors associated with THOP determined by univariate logistic regression analysis. Conclusıons Although some treatment practices might have had direct effects on pituitary–thyroid axis, related with the severity of the newborn clinical conditions, non of them was found to be a associated factor for THOP. However, CHD and SGA may be considered as associated factors with THOP detected in preterm infants.

Silent corticotroph tumors are composed of corticotroph cells, but do not manifest any biochemical or clinical evidence of hypercortisolism. A choristoma is a benign, congenital proliferation of histologically mature tissue elements normally not present at the site of occurrence. The existence of adrenocortical cells within the pituitary gland, which can be explained as a choristoma, is a very rare entity, and the co-occurrence of these two entities have only been reported in few cases. We report an 11-year-old boy with central hypothyroidism. On cranial magnetic resonance imaging a pituitary tumor was detected, and histopathological studies led to a diagnosis of an adrenal choristoma and a silent corticotroph tumor in the pituitary gland. The presence of adrenocortical cells were confirmed by positive calretinin, inhibin and Melan A staining, and the corticotroph cells by immunohistochemistry demonstrating adrenocorticotropic hormone positivity. Herein, we report the fourth and the youngest case of silent corticotroph tumor with adrenocortical choristoma in the literature. Even though the underlying mechanism is not fully understood, suggested mechanisms are discussed.

von Hippel-Lindau (VHL) disease is an autosomal dominantly inherited disorder, characterized by hemangioblastomas of the retina and central nervous system (CNS); renal cysts; clear cell carcinoma; pheochromocytoma (PCC); endolymphatic sac tumors; cystadenomas of the epididymis in males; broad ligament of uterus in females; pancreatic cysts; cystadenomas; and neuroendocrine tumors. We report two cases of VHL disease that presented with PCC as the first manifestation. Further clinical developments during follow-up, hemangioblastoma of CNS in one case and a pancreatic neuroendocrine tumor (PNET) in the second case led to the diagnosis of VHL disease. Genetic analyses of the two cases revealed p.Arg161Gln (c.482G>A) and p.Leu129Pro (c.386T>G) heterozygous missense mutations in the VHL gene, respectively. In children, PCC may be the only and/or initial manifestation of VHL with delayed manifestations of the syndrome in other organs. PNET is a very rare manifestation of VHL disease. To the best of our knowledge, this is only the second reported case presenting with a combination of a PNET and bilateral PCC as components of childhood VHL disease. Pediatric patients diagnosed with PCC should be investigated for genetic causes and especially for VHL.

Objective: Although the sensitivity and specificity of bilateral inferior petrosal sinus sampling (BIPSS) were shown to be quite high in adult patients, pediatric studies are limited in number and have conflicting results, since BIPSS is much less commonly performed in children. The aim of this study was to assess the role of BIPSS in the detection and accuracy of lateralization of pituitary adenomas in pediatric patients with Cushing disease (CD) and its possible advantage over other diagnostic methods. Methods: This was a multicenter, nationwide, web-based study. The diagnostic value of BIPSS in 16 patients, aged between four and 16.5 years with a confirmed diagnosis of CD, was evaluated retrospectively. The sensitivity and specificity of BIPSS and magnetic resonance imaging (MRI) were calculated, and compared statistically. Results: Standard tests, except for morning cortisol level, were effective in proving the presence of Cushing syndrome. While MRI findings were consistent with microadenoma in eight cases (50%), CD presence and lateralization was successfully predicted in 14 of 16 patients using BIPSS. BIPSS compared with MRI examination was significantly more accurate, both in pre-stimulation and post-stimulation results (p=0.047 and p=0.041, respectively). BIPSS showed a significantly higher sensitivity (92.8%) than MRI in detecting the pituitary source of adrenocorticotropic hormone secretion. Conclusion: These results suggest that BIPSS is superior to MRI for diagnostic work-up to confirm the diagnosis of CD. Moreover, in line with previous studies, BIPSS was shown to provide better information about adenoma location, which is vital for possible surgical intervention.