Perioperative Thyroid-Metabolic Changes in Pancreatic Ductal Adenocarcinoma According to Surgical Management

Background: Pancreatic ductal adenocarcinoma (PDAC) is associated not only with tumor progression but also with profound metabolic and nutritional disturbances. Thyroid hormone homeostasis may reflect this systemic response; however, perioperative data in PDAC remain limited. We aimed to assess perioperative changes in thyroid-related parameters in patients with PDAC undergoing different types of surgical management and to explore their associations with nutritional, metabolic, and tumor-burden variables. Methods: We performed a retrospective single-center study including 101 patients with PDAC. Thyroid-related and metabolic laboratory parameters were assessed before surgery and again 4-6 weeks later. The analyzed variables included thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), the FT3/FT4 ratio, albumin, total protein, glucose, insulin, HbA1c, lipid parameters, and CA 19-9. Patients were analyzed according to resectional versus non-resectional treatment and according to four procedure types. The primary endpoint was perioperative change in the FT3/FT4 ratio. Results: At baseline, resectional patients had significantly higher FT3 and FT3/FT4 ratio values and lower FT4 and CA 19-9 levels than non-resectional patients. In the whole cohort, FT3 and the FT3/FT4 ratio decreased significantly after treatment, whereas TSH increased, and FT4 remained unchanged. These endocrine changes occurred in parallel with significant declines in albumin, total protein, glucose, insulin, HbA1c, and HDL cholesterol, together with an increase in triglyceride levels. Baseline FT3 and FT3/FT4 ratios correlated positively with albumin and total protein and negatively with CA 19-9. Although perioperative changes did not differ significantly between resectional and non-resectional groups except for triglycerides, significant procedure-dependent differences were observed across the four surgical categories for FT3, FT4, TSH, and the FT3/FT4 ratio; glucose; insulin; and triglycerides. The prevalence of low-T3 syndrome increased from 11.1% preoperatively to 38.7% postoperatively. Conclusions: In PDAC, perioperative changes in thyroid hormone indices are pronounced and strongly depend on the type of surgical management. FT3 and the FT3/FT4 ratio appear to reflect systemic metabolic and nutritional adaptation as well as disease burden rather than acting as tumor-specific markers.