Zafer Pekkolay

Background: Vitamin D deficiency is a common global health problem and remains highly prevalent in Türkiye, where limited food fortification and heterogeneous clinical practices contribute to variability in testing and supplementation strategies. Aims: To provide Türkiye-specific best practice recommendations for defining clinically relevant serum 25-hydroxyvitamin D [25(OH)D] thresholds, identifying adult risk groups for targeted testing, and recommending evidence-based prevention, treatment, and monitoring approaches while minimizing under-treatment and inappropriate high-dose use. Methods: This national expert consensus document was developed by endocrinologists from across Türkiye using a structured, modified Delphi methodology. Draft statements informed by systematic literature reviews were rated via online surveys using a 9-point Likert scale, followed by two Delphi rounds and a face-to-face consensus meeting in İstanbul in October 2025. Results: Recommendations addressed sun exposure, laboratory assessment, screening, supplementation, treatment, and follow-up. Serum 25(OH)D <20 ng/mL was defined as deficiency and <12 ng/mL as severe deficiency, with a target range of 20–50 ng/mL. Routine population-wide screening was not recommended; instead, targeted testing in high-risk adults and symptom-driven biochemical evaluation were endorsed. Empiric supplementation was recommended for selected high-risk groups, with cholecalciferol as the preferred agent. Higher individualized doses were suggested in obesity or malabsorption, while loading regimens were reserved for specific clinical indications, such as severe deficiency or certain medical conditions that impair vitamin D metabolism. Reassessment of 25(OH)D at 8–12 weeks was recommended. Conclusion: These consensus-based recommendations provide a practical, context-specific framework for assessing, preventing, treating, and monitoring vitamin D deficiency in adults in Türkiye.

Backgound: Suppression of thyroid-stimulating hormone (TSH) can adversely affect bone tissue in individuals with differentiated thyroid cancer (DTC).In a multi-center setting, this study aim to examine vertebral fractures (VF) and bone mineral density (BMD) in DTC patients receiving levothyroxine (LT4) suppression therapy. Methods: Clinical measurements done in the last visit, laboratory and radiologic data extracted from patients files. Serum TSH concentrations were divided into four groups based on the American Thyroid Association’s guidelines for TSH suppression: 0.01 mu/L, 0.01-0.1, 0.1–0.5 mu/L, and >0.5 mu/L. Within the preceding year, the BMD measurements obtained in the lumbar and femoral regions with a DXA scanner were recorded. Lateral spinal X-rays obtained within the previous year were evaluated. Results: The study comprised 990 people with DTC. The DXA showed 545 patients with normal BMD, 82 (8.2%) with osteoporosis, and 363 (36.6%). patients had osteopenia. The osteoporotic group exhibited older age (p = 0.001), lower BMI (p = 0.001), and comparable TSH levels compare to the osteopenia and normal BMD groups. In 476 lateral vertebral x-rays, 200 (42%), 131 (27.5%) were significant or severe VF. The severe TSH suppression group had a greater fracture rate than the moderate, mild, and non-suppressed groups(p=0.013). VF patients were older (p = 0.001) and had lower femur neck and L1-L4 BMD. Disease duration, FT4 level, and femur neck BMD affected fracture risk (p = 0.001, pseudo R2: 0.028). Age, femur neck BMD, L1-L4 BMD, and osteocalcin levels were linked with osteoporosis in a multivariate analysis (p = 0.001, pseudo R2: 0.427). TSH subgroups had similar femur neck (p = 0.61) and L1-L4 BMD (p = 0.89). Conclusion: Findings suggest that DTC patients undergoing TSH suppression have a significant risk of VF. Assessment of VF should be integrated into the routine care of DTC survivors to ensure long-term skeletal safety.

Objective: Breast cancer is the most common cancer in women. Mortality in breast cancer is associated with recurrence and metastases. The aim of this study was to determine the causes of local recurrence and metastasis in operated early stage breast cancer. Material and Methods: The files of the patients diagnosed with operated early stage breast cancer followed up at Dicle University Medical Faculty Medical Oncology Department between 2001-2010 were analyzed retrospectively. The group of patients with recurrence was referred to as the relapse-metastasis group and the other patients were called the remission group. Between these two groups, age, sex, tumor histology, size, presence of lymphovascular invasion, tumor grade molecular properties such as, ER, PR, HER, staging studies; time characteristics, surgical characteristics, time between surgery-chemotherapy and surgery-radiotherapy; The relapse-metastasis group and the remission group were compared in terms of chemotherapy. SPSS 22 was used for statistical analysis. p<0.05 was considered significant. Results: 479 patients were included in the study. The number of patients in the remission and relapse-metastasis group was 343 and 136, respectively. Tumor diameter was 3.33 cm in the remission group and 4.58 cm in the relapse-metastasis group, and the difference was statistically significant (p<0.01). The percentage of involvement of more than 4 lymph nodes were 30.45% and 55.7% in the remission and relapse-metastasis groups, respectively (p 1 month was 9.7% and 24% in the remission and relapse-metastasis group, respectively. In remission group 30.9%; relapse-metastasis group 47.7% of the patients had incomplete staging at the time of diagnosis. Conclusion: The factors determining the recurrence in patients with operated early stage breast cancer were tumor size, number of lymph node involvement, incomplete staging at the time of diagnosis, start chemotherapy later than 1 month.