Thyroid nodules are a common clinical finding, with their prevalence influenced by multiple environmental and occupational factors, including exposure to ionizing radiation. Healthcare workers, particularly those operating in radiology, nuclear medicine, interventional cardiology, and radiation oncology, are potentially at increased risk due to chronic low-dose radiation exposure. This review aims to evaluate the current evidence regarding the association between occupational radiation exposure and the development of thyroid nodules among healthcare professionals. The findings suggest a higher prevalence of thyroid nodules in radiation-exposed workers compared to the general population, although data heterogeneity and methodological limitations exist. Factors such as the duration of exposure, radiation protection practices, and frequency of monitoring play critical roles in modulating the individual risk. While some studies report no significant difference in malignancy rates, the increased detection of nodules underlines the need for regular thyroid surveillance in at-risk populations. Further longitudinal and multicentric studies are warranted to clarify the causality and guide preventive strategies. This review highlights the importance of occupational health protocols, including radiation shielding and periodic thyroid evaluation, in safeguarding the long-term endocrine health of healthcare workers.

Introduction/Background: Immune checkpoint inhibitors (ICIs) play a central role in advanced cancer treatment, but they are associated with immune-related adverse events (irAEs) that include two cases of hypercalcemia induced by the programmed death-1 (PD-1) inhibitor, pembrolizumab. We report a unique case of a colon cancer patient treated with pembrolizumab who acutely developed life-threatening hypercalcemia. Case Presentation: This case presents a seventy-five-year-old woman suffering from colon adenocarcinoma with liver metastasis undergoing pembrolizumab therapy. Shortly after its second administration, she developed severe hypercalcemia (21 mg/dL) with acute kidney failure. Serum intact parathyroid hormone (PTH), parathyroid hormone-related peptide (PTHrP), 25-OH vitamin D, and 1,25-OH vitamin D were suppressed while computerized tomography (CT) imaging ruled out relevant osteolytic or granulomatous lesions. Treatment included hydration, infusion of zoledronic acid, and high-dose glucocorticoids. The patient';s serum calcium levels normalized, andher condition improved. Primary hyperparathyroidism, ectopic PTHrP secretion, and ectopic 25(OH) D-1-hydroxylase expression were ruled out by clinical and laboratory data. Notably, experimental models of PD-1/PD-L1 inhibition have demonstrated increased bone resorption. Although the absence of specific bone turnover markers and a recent 18FDG-PET/CT scan partly limits the understanding of the pathophysiological mechanism, immune-mediated osteoclast activation represents a potential pathophysiological mechanism of acute reversible hypercalcemia. Conclusion: The present case is unique due to its early onset, absence of calcitriol and PTHrP elevation, and rapid response to corticosteroids. Serum calcium should be assessed both before each ICI's dose administration and throughout treatment in case of symptoms suspicious for hypercalcemia to prevent the onset and progression of this rare but critical irAE.