Evaluation of 25-hydroxyvitamin D (25(OH)D) levels before and during the COVID-19 pandemic: A cross-sectional study and trend analysis involving 86,772 samples.

Background: The aim of this paper was to evaluate the change in 25-hidroxyvitamin D (25(OH)D) levels before and during the COVID-19 pandemic.

Methods: In this retrospective, cross-sectional and methodological study included 86,772 patients (18-75 years) samples who were admitted to the Izmir Dokuz Eylul University Hospital (latitude and longitude (Turkey): 27 E 09; 38 N 25, respectively) for various reasons and whose 25(OH)D levels were measured in the biochemistry unit between 2019-2020 and 2020-2021 (before and during the COVID-19 outbreak). A time series analysis of monthly averages for 25(OH)D was performed.

Determining the age group-based cut-off values of serum anti-Mullerian hormone concentrations to diagnose polycystic ovary syndrome.

Objective: To determine the cut-off values of the serum anti-Müllerian hormone (AMH) concentration for different age groups (21-25, 26-30, 31-35 years) to diagnose polycystic ovary syndrome (PCOS).

Methods: In total, 187 women aged 21-35 years were included in this descriptive study. Patients diagnosed with PCOS according to the Rotterdam Criteria formed the PCOS group ( = 93), whereas those without symptoms related to PCOS formed the control group ( = 94).

Effect of serum 25-hydroxyvitamin D level on lung, breast, colorectal and prostate cancers: a nested case-control study.

Background: Published studies show that vitamin D deficiency is widespread and it has been suggested that it increases the risk of lung, breast, colorectal and prostate cancers.

Aims: To investigate prospectively the effect of serum 25-hydroxyvitamin D (25(OH)D) level on lung, breast, colorectal and prostate cancers in people aged 30+ years.

Methods: In this nested case-control study, the data and collected serum samples from a cohort study, the Balçova Heart Study, during 2007-09, were used.

Hepatitis A, B and C seropositivity among first-year healthcare students in western Turkey: a seroprevalence study.

Background: The risk of viral hepatitis among healthcare students (HCSs) is greater than that among the general population. Therefore, this study was conducted to investigate the seroprevalence of the hepatitis A virus (HAV), hepatitis B virus (HBV) and hepatitis C virus (HCV) among first-year HCSs at a university in Turkey and as a secondary objective, to determine the factors associated with HAV and HBV seropositivity.

Methods: This cross-sectional study was performed in first-year HCSs in Izmir, western Turkey.

The role of melatonin and cortisol circadian rhythms in the pathogenesis of infantile colic.

Background: Despite the high prevalence of infantile colic, the pathogenesis remains incompletely understood. Cortisol and melatonin hormones affect gastrointestinal system development in several ways, and interestingly, both cortisol and melatonin's circadian rhythms begin around the 3rd month in which infantile colic symptoms start to decrease. We hypothesized that infantile colic might associate with desynchronization of normal circadian rhythms of these hormones.