The Relationship Between Pituitary Axis Hormones and All-Cause Mortality in Hospitalized Patients with Chronic Diseases: A Prospective Cohort Study

<i>Background and Objectives</i>: The pituitary gland plays a central role in endocrine regulation, and chronic illnesses may disrupt pituitary axis function, potentially influencing clinical outcomes. In this study, we aimed to thoroughly investigate the effects of the pituitary axis on all-cause mortality in patients with chronic diseases. <i>Materials and Methods</i>: This prospective observational cohort study included 526 patients with chronic diseases lasting longer than six months who were hospitalized in the Internal Medicine Department of a training and research hospital in Istanbul between 7 May and 30 November 2023. Hormonal parameters were measured within the first 72 h of admission. Demographic characteristics, comorbidities, laboratory findings, intensive care unit (ICU) transfer, and mortality outcomes were recorded. Multivariable binary logistic regression analysis was used to identify independent predictors of mortality. <i>Results</i>: Patients who died were significantly older (75.60 ± 12.6 years, <i>p</i> < 0.001) and had lower free triiodothyronine (FT3) levels (<i>p</i> < 0.001). In hierarchical multivariable logistic regression analysis, increasing age, lower serum albumin levels, immobilization, low FT3 levels, and abnormal luteinizing hormone (LH) levels (defined as values outside sex- and menopausal status-adjusted reference intervals) were independently associated with 6-month mortality. The addition of hormonal parameters significantly improved model performance beyond traditional markers of illness severity. <i>Conclusions</i>: Alterations in pituitary axis hormones, particularly deviations in LH levels and reduced FT3 levels, are independently associated with mortality in hospitalized patients with chronic diseases. These findings suggest that pituitary hormone profiles may contribute to the stratification of mortality risk in this population.