Background: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are graded per the World Health Organization (WHO) using mitotic count and the Ki-67 index. There is an ongoing debate regarding the concordance between these parameters and their ability to predict metastatic disease. Objective: The objective is to assess concordance between the mitotic count and the Ki-67 index in grading GEP-NETs and to determine which parameter more accurately relates to metastatic disease and local tumor behavior. Methods: We conducted a single-center retrospective cohort study of adults with GEP-NETs managed between January 2006 and February 2024. Tumors were staged according to the TNM system. Grading followed WHO criteria using mitotic count and the Ki-67 index; when discordant, the higher grade was assigned. Results: Concordance between mitotic count- and Ki-67-based grading was 76.5% (78/102) with Cohen’s κ = 0.36, indicating fair-to-moderate agreement. More tumors were classified as G1 by mitotic count (86.3%) than by the Ki-67 index (68.6%). Neither mitotic count nor the Ki-67 index (numerical values or grades) showed a significant association with metastatic disease (all p > 0.05). Mitotic count (as a numerical continuous values) correlated with tumor invasion (T1 vs. T3, p = 0.035; T1 vs. T4, p = 0.036), whereas the Ki-67 index did not (p = 0.11). Tumor size was the strongest predictor of metastases (lymph-node p = 0.028; distant p < 0.001; any p < 0.001). Conclusions: Mitotic count and the Ki-67 index show only 76.5% concordance. Neither marker predicted metastatic disease in this cohort, while tumor size was the most robust predictor. These findings support giving greater weight to tumor size within prognostic algorithms while recognizing the limitations of proliferation-based grading for predicting metastasis.

Objectives: To assess success rates and cost-effectiveness of adrenal venous sampling (AVS) after implementing point-of-care rapid cortisol (RC) testing conducted using a europium nanoparticle-based fluoro-immunoassay in patients with primary hyperaldosteronism. Methods: A retrospective review of AVS procedures was conducted at our medical center between January 2016 and June 2024. The primary objective was to compare the success rates of AVS before and after the implementation of the RC testing. Secondary outcomes included a cost–benefit analysis. Results: Of 55 AVS procedures, 19 were conducted using RC testing and 36 were in the historical control cohort. The success rates for right vein sampling were 79% and 67%, respectively. Overall, in six (31.5%) patients in the RC cohort, a low RC selectivity index (SI) value, calculated within 10 min, enabled determination of unsuccessful cannulation and need for resampling during the same AVS session. Repeated sampling resulted in successful procedures in two cases (10.5%) and unsuccessful AVS in four cases, nonetheless sparing the need for repeated AVS sessions in 31.5% of cases. Utilizing RC potentially spared 6 patients from repeated AVS sessions, and considering the additional expenses on the RC test, its use afforded cost savings of an average of $1288 per patient. Conclusions: We demonstrated the cost-effectiveness of utilizing RC measurement in sparing the need for repeated AVS sessions. RC measurement during AVS enabled identification of correct catheter placement in real time, allowing for prompt decisions regarding the need for additional sampling attempts, thereby reducing subsequent costs of repeated AVS sessions.

Background and Clinical Significance: Congenital hyperinsulinism (CHI) is a disorder involving excessive insulin secretion due to mutations in the insulin regulation pathways. Patients are typically diagnosed during infancy following recurrent hypoglycemic events, which may lead to irreversible neurologic damage if left untreated. Adult presentation and diagnosis are rare. Case Presentation: Here, we report the unusual case of a 41-year-old patient who presented with recurrent episodes of hyperinsulinemic hypoglycemia. An extensive diagnostic evaluation yielded no evidence of an acquired cause. Genetic testing revealed a heterozygous novel c.4078G>C substitution in the ABCC8 gene, which plays a role in the insulin secretion pathway. This variant may have been the cause for CHI going unrecognized during the patient’s childhood and could have also contributed to his uncontrolled convulsive disorder. Treatment with diazoxide and octreotide led to significant clinical improvement, with no severe hypoglycemic events during the final week of hospitalization. Conclusions: This case emphasizes the importance of considering congenital hyperinsulinism in the differential diagnosis of adult patients evaluated for hyperinsulinemic hypoglycemia, especially when standard workup fails to identify an underlying cause.

Background/Objectives: Pre-admission levothyroxine use may influence the interpretation of thyroid tests beyond the conventional framework of non-thyroidal illness syndrome (NTIS). We examined whether thyroid hormone–outcome associations differed by treatment status. Methods: This retrospective study included medical inpatients with thyroid-stimulating hormone (TSH) < 5 mIU/L during 2006–2024. Propensity-score matching used age, sex, and 16 comorbidity indicators. Complete-case negative-binomial and logistic models examined hospitalization length and in-hospital mortality, with treatment-by-hormone interactions. Results: Among 14,332 matched patients, 3717 had complete data (1986 users; 1731 nonusers). Higher free triiodothyronine (FT3) in nonusers was associated with shorter hospitalization (incidence–rate ratio [IRR] 0.76, 95% confidence interval [CI] 0.73–0.80) and lower mortality odds (odds ratio [OR] 0.47, 95% CI 0.35–0.62). Free thyroxine (FT4) associations differed by levothyroxine use for both hospitalization length (interaction IRR 0.95, 95% CI 0.94–0.97) and mortality (interaction OR 0.83, 95% CI 0.77–0.90; both p < 0.001). At mean hormone concentrations, levothyroxine use was associated with shorter hospitalization (IRR 0.87, 95% CI 0.81–0.94) and lower mortality odds (OR 0.53, 95% CI 0.35–0.82). Crude mortality was 4.6% versus 5.0%, respectively; the conditional estimates represent a different comparison. Conclusions: FT4–outcome associations differed by pre-admission levothyroxine use, extending the established low-T3 prognostic framework to treatment-specific hormone patterns. These findings support considering treatment history when interpreting inpatient thyroid tests. Selective testing and residual confounding limit causal interpretation.