Citations

Abstract Purpose: Relapse is a major cause of failure in human papillomavirus–independent head and neck squamous cell carcinoma. Clinicopathologic criteria for adjuvant treatment remain imprecise and have not changed for decades. We investigated whether ctDNA in lymphatic exudate collected via surgical drains (“lymph”) 24 hours after surgery identified molecular residual disease (MRD) and compared its performance with time-matched plasma. Experimental Design: Using an ultra-sensitive tumor-informed sequencing approach, tumor variants were called in lymph and plasma to classify patients as ctDNA positive or ctDNA negative, trained in an initial cohort of 36 patients, and replicated in an independent cohort of 37 patients. Progression-free survival was compared in ctDNA(+) versus ctDNA(–) patients. Results: Lymph identified MRD in two independent multi-site cohorts (initial cohort sensitivity = 76% and specificity = 63%; log-rank P = 0.01; replication cohort sensitivity = 65% and specificity = 70%; log-rank P = 0.04). Lymph performance was enhanced in locoregional relapse (sensitivity = 78% and specificity = 67%; log-rank P = 0.0004) and generalized to early-stage patients. Analysis of matched plasma collected at this early timepoint was not predictive of recurrence (sensitivity = 35% and specificity = 72%; log-rank P = 0.7). In patients with intermediate-risk pathology, lymph ctDNA was associated with recurrence (sensitivity = 88% and specificity = 67%; log-rank P = 0.0008), suggesting an opportunity for improved stratification of patients who may benefit from additional adjuvant treatment. Conclusions: Postoperative lymph is a novel, proximal, and early source of MRD with the potential to introduce more precision into adjuvant therapy decision-making and improve outcomes, especially for patients with intermediate-risk human papillomavirus–independent head and neck squamous cell carcinoma.

Background: Breast cancer polygenic risk scores (PRS) and traditional risk models (e.g., the Gail model [Gail]) are known to contribute largely independent information, but it is unclear how the overlap varies by ancestry, age, disease type (invasive breast cancer, DCIS), and risk threshold. Methods: In a retrospective case–control study, we evaluated risk prediction performance in 180,398 women (161,849 of European ancestry; 18,549 of Asian ancestry). Odds ratios (ORs) from logistic regression models and the area under the receiver operating characteristic curve (AUC) were estimated. Results: PRS for invasive disease showed a stronger association in younger (<50 years) women (OR = 2.51, AUC = 0.622) than in women ≥ 50 years (OR = 2.06, AUC = 0.653) of European ancestry. PRS performance in Asians was lower (OR range = 1.62–1.64, AUC = 0.551–0.600). Gail performance was modest across groups and poor in younger Asian women (OR = 0.94–0.99, AUC = 0.523–0.533). Age interactions were observed for both PRS (p < 0.001) and Gail (p < 0.001) in Europeans, whereas in Asians, age interaction was observed only for Gail (invasive: p < 0.001; DCIS: p = 0.002). PRS identified more high-risk individuals than Gail in Asian populations, especially ≥50 years, while Gail identified more in Europeans. Overlap between PRS, Gail, and family history was limited at higher thresholds. Calibration analysis, comparing empirical and model-based ROC curves, showed divergence for both PRS and Gail (p < 0.001), which indicates miscalibration. In Europeans, family history and prior biopsies drove Gail discrimination. In younger Asians, age at first live birth was influential. Conclusions: PRS adds value to risk stratification beyond traditional tools, especially in younger women and Asian ancestry populations.

Introduction: Photoplethysmography-based (PPG) devices represent a significant advancement in noninvasive cardiovascular monitoring. These cuffless technologies enable assessment of hemodynamic parameters with improved comfort, usability and compliance. Modern PPG systems have expanded their capabilities to include advanced metrics such as systemic vascular resistance (SVR) and cardiac output (CO). Many antihypertensive drugs lower blood pressure by reducing SVR through vasodilatation of the systemic and renal vasculature. Limited data is available on SVR during ambulatory monitoring. PPG devices become more common as they allow us to assess SVR in real life, in ambulatory blood pressure monitoring (ABPM) patients. Aim: To evaluate and compare SVR using the Biobeat (WP613) device across patient groups. Methods: Adults from the Hypertension Clinic at University of Miami, Florida, from Aug. 2023–Jan. 2025 underwent 24-h ABPM monitoring using Biobeat device. Patient data was matched with Biobeat. PPG data was available every 15 minutes; The raw data included SBP and DBP, the heart rate, stroke volume, CO and SVR. Results: A total of 539 patients underwent PPG ABPM during the study period. The median was 62 (IQR 54, 71) years, with 57% females (Tab 1) . Patients were defined as hypertensive per AHA 2017 guidelines [SBP≥130 and DBP≥80 mmHg]. Overall, 265 patients were classified as having normal BP, 95 as having isolated systolic hypertension, and 179 as having mixed hypertension. Within the Mix-HTN group, 42 patients had isolated diastolic hypertension and the remaining 137 systolic and diastolic hypertension (Fig 2) . In subgroup analysis (Fig 3); SVR was significantly different between the groups: lowerst in No/C-HTN and highest in Mix-HTN. particularly among the mixed-hypertension group, SVR was higher in the Systolic and Diastolic HTN compared to the Isolated diastolic HTN group. Among the No/C-HTN group, 60 patients were not hypertensives and 205, were hypertensives on at least 1 drug. The SVR was not statistically significant between these 2 subgroups, suggesting that SVR may be a helpful target biomarker used to up-titrate antihypertensives. Conclusion: PPG devices offer a valuable enhancement to conventional ABPM by providing additional physiological measurements such as SVR that can help differentiate between various hypertension phenotypes and potentially provide personalized therapy that target the driver of hypertension.

Introduction: Cardiovascular risks following SARS-CoV-2 infection are incompletely defined. We evaluated evolving cardiovascular outcomes across COVID-19 variant eras using a large community-based cohort to inform risk stratification and clinical care. Methods: We conducted a retrospective cohort study of 162,471 adults with COVID-19 between March 2020 and December 2023 using the Rochester Epidemiology Project. Patients were stratified by variant era (Pre-Delta, Delta, and Omicron). Cardiovascular outcomes included major adverse cardiovascular events (MACE: myocardial infarction, stroke, death), ischemic and inflammatory heart disease, thrombotic events, and dysrhythmias. Diagnoses were identified using ICD-10 codes and validated in a subset. Cumulative incidence was estimated using Kaplan-Meier and competing risk models. Cox proportional hazards regression was used to assess differences by era and age. Results: MACE occurred in 4,922 patients, primarily in those ≥80 (2-year incidence: 17%). Event rates peaked within 30 days post-infection, with marked variation by variant. In patients ≥80, 30-day MACE risk was highest in the Pre-Delta (HR 3.85; 95% CI, 3.14–4.71) and Delta (HR 2.72; 95% CI, 2.13–3.47) eras versus Omicron. After 30 days, event rates fell and era differences narrowed. Thrombotic events (n=2,090; 1.4%) decreased across eras. Ischemic and inflammatory heart disease rates were stable. Myocarditis/pericarditis were rare (0.1%) without age trends. Dysrhythmias affected 6,765 patients (2-year incidence: 4.9%) and rose with age (2.0% in <40 vs. 19.9% in ≥80). Within 30 days, risk was higher in the Pre-Delta and Delta eras for age ≥40, especially ≥80 (Delta HR 3.08; 95% CI, 2.08–4.56) and 60–79 (HR 2.23; 95% CI, 1.75–2.85). Among those 40–59, Delta posed the highest risk (HR 2.74; 95% CI, 1.94–3.86 vs. Pre-Delta HR 1.77; 95% CI, 1.26–2.49). No differences were observed in <40. Beyond 30 days, risk converged across variants. Conclusion: Cardiovascular risk after SARS-CoV-2 infection was concentrated in the first 30 days, with attenuation thereafter. While MACE and thrombotic event rates declined over time, early dysrhythmia risk varied by variant and age, especially in older adults. These findings define a time-sensitive, variant-specific risk window and support short-term, risk-stratified post-COVID monitoring. This work informs targeted follow-up protocols by infection era and age, with implications for quality improvement, resource use, and equitable care.

Background: Pathogenic/likely pathogenic (P/LP) variants in the RBM20-encoded RNA-binding protein motif 20 splicing factor result in a penetrant form of arrhythmogenic/dilated cardiomyopathy (ACM/DCM) characterized by ventricular arrhythmias (VA) and early-onset heart failure. The role of cardiac magnetic resonance (CMR) imaging in characterizing RBM20 cardiomyopathy and guiding risk stratification remains inadequately defined. Objectives: To characterize CMR phenotypes in patients with RBM20 cardiomyopathy and explore associations between variant type, CMR phenotype, and VA risk. Methods: Retrospective analysis of 1,061 genotype-positive ACM/DCM patients was used to identify individuals with P/LP arginine/serine-rich domain-localizing missense (RBM20msv) or truncating (RBM20tv) variants in RBM20. Clinical outcomes, including major VA (MVA; sudden cardiac arrest, sustained ventricular arrhythmia, or appropriate ICD therapy) events, were compared between RBM20msv and RBM20tv-positive patients. When available, CMR findings were also analyzed by variant type and correlated with MVA events. Results: Overall, 64 of 1,061 (6%) ACM/DCM patients possessed an RBM20msv or RBM20tv. Of those, 35 (mean age 38±16 years, 54% female, 94% Caucasian) underwent CMR. Late gadolinium enhancement (LGE) was present in 9/35 (26%), typically in a mid-myocardial septal or inferolateral pattern. Left ventricular (LV) noncompaction was noted in 9/35 (26%). Within the CMR subgroup, RBM20msv accounted for 29/35 (83%) of cases, while RBM20tv was observed in 6/35 (17%). No significant difference in LV ejection fraction (36±7% vs. 42±13%, p=0.358), LV end-diastolic volume index (100±32 mL/m2 vs. 118±44 mL/m2, p=0.342), or LGE prevalence (1/6 [17%] vs. 8/29 [28%], p=1.000) was observed between RBM20tv- and RBM20msv-positive patients. However, MVA events were more frequent among RBM20tv-positive patients in the CMR subset (3/6 [50%] vs. 2/29 [7%], p=0.026) and the overall cohort (7/15 [47%] vs. 6/49 [12%], p=0.008). Conclusions: RBM20tv-positive patients experienced a higher rate of MVA events despite similar rates of LGE and structural remodeling compared to those with RBM20msv. Future studies are needed to determine whether mechanisms independent of fibrosis/re-entry drive arrhythmogenesis in RBM20tv-positive patients and to establish if RBM20tv represents an independent risk factor for MVA events that merits incorporation into genotype-specific risk stratification strategies.

Anthracyclines are potent chemotherapeutic agents, yet their clinical use is hampered by their cardiotoxicity. Anthracyclines achieve potent anti- cancer effects primarily via TOP2A, but at the same time they induce a dose limiting cardiotoxicity through TOP2B. The use of a catalytic TOP2 inhibitors such as dexrazoxane (ICRF 187) significantly reduces the incidence of anthracycline-induced cardiotoxicity. However, dexrazoxane targets the highly conserved TOP2 dimer interface that is identical between TOP2A and TOP2B, fostering persisting concerns that its inhibition of TOP2A isoenzyme may interfere with anthracycline anticancer effects and augment anthracycline-induced myelosuppression. Thus, isoform- selective TOP2 inhibitors that can control the DNA damage caused by TOP2A vs TOP2B are a significant unmet clinical need. We have developed a new class of highly potent and TOP2B-selective catalytic inhibitors through rational design by building upon the general pharmacophore present in isolates from Calophyllum Brasiliense. Using X-ray crystallography, we demonstrate that our newly developed compounds occupy a previously unidentified druggable binding-site in the TOP2 ATPase domain and function as a physical barrier to block the conformational change triggered by ATP hydrolysis. We have named the class of inhibitors that target this site “obex”, the Latin word for obstacle. The obex binding site contains residues that differ between the TOP2A and TOP2B isoenzymes, based on which we rationally designed, prepared, and systematically evaluated a targeted panel of obex inhibitors. We have identified the lead molecule, namely, topobexin, as the first- in-class TOP2B-specific obex inhibitor that can prevent anthracycline-induced DNA damage. This first TOP2 isoform-specific inhibition underscores the broader potential to improve drug specificity and minimize adverse effects in various medical treatments.

Abstract Disclosure: C.A. Villavicencio Torres: None. S. Ahmadian: None. K. Moehnke: None. V.M. Fell: None. R.L. Taylor: None. S.K. Grebe: None. A.D. Maus: None. I. Bancos: None. Background: Evaluation of adrenal disorders relies on total cortisol measurements at baseline or during dynamic testing. Accurate cortisol assessment that avoids phlebotomy may simplify the work up of adrenal disorders, decrease healthcare costs, and improve patient experience. Objectives: We aimed to compare cortisol and dexamethasone concentrations between venipuncture-based (clinical) and capillary blood samples. Methodology: We conducted a cross-sectional study (July 2024-April 2025) of adults undergoing standard-of-care cortisol measurements. Capillary blood samples were collected alongside clinical samples. Capillary measurements included total cortisol and dexamethasone (mass spectrometry). Clinical samples were tested for total cortisol (Roche immunoassay) and dexamethasone (mass spectrometry). Results: Of 318 patients (243, 77% women, median age 53 years, IQR 39-66), 227 (71%) underwent dexamethasone suppression test (DST) and 88 (28%) cosyntropin stimulation test (CST). Capillary blood collection failed in 13 (4%) patients. In patients undergoing DST, median post-dexamethasone serum cortisol was 1.3 mcg/dL (IQR 0.8-2.2), and serum dexamethasone was 0.41 mcg/dL (IQR 0.27-0.59), while median capillary cortisol was 1.5 mcg/dL (IQR 1-2.5), and capillary dexamethasone was 0.33 mcg/dL (IQR 0.21-0.51). Capillary cortisol (r=0.95, 95% CI [0.93, 0.96], p&lt;.0001) and capillary dexamethasone (r=0.93, 95% CI [0.90, 0.95], p&lt;.0001) showed strong correlation with their respective clinical measurements. In patients undergoing CST, median baseline serum cortisol was 7.5 mcg/dL (IQR 5-10), and median baseline capillary cortisol was 8.5 mcg/dL (IQR 6-12). Median post-CST 60-minute serum cortisol was 23 mcg/dL (IQR 20-25), while capillary cortisol was 25 mcg/dL (IQR 21-28). Baseline (r=0.77, 95% CI [0.66, 0.85], p&lt;.0001) and post-CST 60-minute capillary cortisol (r=0.88, 95% CI [0.81-92], p&lt;.0001) strongly correlated with clinical measurements. Post-dexamethasone cortisol in paired DST samples showed that capillary measurements were higher than serum cortisol (median difference 0.20 mcg/dL (95% CI [0.12, 0.42], p&lt;.0001), while paired capillary dexamethasone concentrations were lower than serum dexamethasone concentrations (median difference 0.04 mcg/dL (95% CI [0.03, 0.07], p&lt;.0001). In CST, paired baseline capillary and serum cortisol concentrations were similar (median difference 0.10 mcg/dL, 95% CI [0.3, 0.3], p=.3660), while paired post-CST 60-minute capillary cortisol was higher than serum cortisol by a median of 2.8 mcg/dL (95% CI [2, 3.2], p&lt;.0001). Conclusion: Capillary cortisol and dexamethasone concentrations demonstrate excellent correlation with venipuncture-based measurements. Following validation with at-home collection, capillary blood measurements may serve as an alternative for evaluating adrenal disorders. Presentation: Sunday, July 13, 2025

Abstract Disclosure: C.A. Villavicencio Torres: None. S. Ahmadian: None. V.M. Fell: None. K. Moehnke: None. Y. Chai: None. R.L. Taylor: None. S.K. Grebe: None. A.D. Maus: None. I. Bancos: None. Background: Current standard-of-care assessment of adrenal disorders relies on the venipuncture-based total cortisol measurements. Salivary cortisol (SalF) and cortisone (SalE) measurements have advantages such as a more accurate assessment of patients with cortisol-binging globulin abnormalities and the convenience of at-home non-invasive testing. Aims: This study aimed to compare concentrations of cortisol and dexamethasone between clinical (venipuncture-based) and saliva samples. Methodology: We conducted a cross-sectional study (July 2024-January 2025) of adults undergoing overnight dexamethasone suppression test (DST) or cosyntropin stimulation test (CST). Saliva samples were collected alongside clinical samples. Saliva measurements included cortisol, cortisone, and dexamethasone (mass spectrometry), while clinical samples were tested for total cortisol (Roche immunoassay) and, in a subgroup, dexamethasone (mass spectrometry). Results: Of 241 patients (186 (77%) women, median age 53 years (IQR 39-66)), 178 (74%) provided samples as a part of DST and 63 (26%) as a part CST. An inability to provide sufficient saliva for analysis was found in 5 patients (2%). In patients undergoing DST, median post-dexamethasone serum total cortisol was 1.3 mcg/dL (IQR 0.8-2.2), and median serum dexamethasone (SerD) was 0.43 mcg/dL (IQR 0.3-0.6) based on clinical samples, while median SalF was 10.2 ng/dL (IQR 6.6-23.6), SalE was 78.6 ng/dL (IQR 52.8-131.1), and saliva dexamethasone (SalD) was 60 ng/dL (IQR 41-93). SalE (r=0.92, p&lt;.0001) demonstrated a stronger correlation than SalF (r=0.85, p&lt;.0001) when compared with post-dexamethasone serum total cortisol measurements. SalD (r=0.85, p&lt;.0001) correlated with SerD measurements. In patients undergoing CST, median baseline serum total cortisol was 7.2 mcg/dL (IQR 4.6-10) based on clinical samples, while median baseline SalF was 86.6 ng/dL (IQR 38.3-166.3), and median SalE was 707 ng/dL (IQR 347-906). Median peak 60-minute serum total cortisol was 21.5 mcg/dL (IQR 18-24), while SalF was 870.4 ng/dL (IQR 440-2904) and SalE was 2501 ng/dL (IQR 1770-3193). Both baseline (r=0.92, p&lt;.0001) and 60 min peak post-cosyntropin SalE (r=0.84, p&lt;.0001) demonstrated a strong correlation with venipuncture-based measurements. SalF had a weaker than SalE correlation at both baseline (r=0.88, p&lt;.0001) and 60 min peak post-cosyntropin (r=0.79, p&lt;.0001). Conclusion: Our study demonstrates that salivary measurements of cortisone, cortisol and dexamethasone strongly correlate with standard-of-care venipuncture concentrations following DST and CST. SalE showed the stronger than SalF correlation with venipuncture-based serum total cortisol concentrations. Presentation: Sunday, July 13, 2025

Abstract Disclosure: S. Ahmadian: None. C.A. Villavicencio Torres: None. V.M. Fell: None. K.L. Moehnke: None. Y. Chai: None. R.L. Taylor: None. S.K. Grebe: None. A.D. Maus: None. I. Bancos: None. Background: Salivary cortisol (SalF), and cortisone (SalE) interpretation can be influenced by intra-individual variability arising from cortisol secretion cyclicity, assay performance, and sampling techniques. No studies to date have examined the impact of sampling on intra-individual variability. Methods: We conducted a single-center cross-sectional study of adults evaluated with total serum cortisol measurements as a part of the overnight dexamethasone suppression test (DST) or cosyntropin stimulation test (CST), November 2024- January 2025. Participants were provided with two cotton swabs (salivettes) and asked to collect two consecutive saliva samples immediately after the venipuncture for total cortisol. Each cotton swab was kept in the mouth for 2-2.5 minutes. Saliva was tested for SalF and SalE by mass spectrometry. Variability was examined based on cortisol tertiles. Results: A total of 78 paired saliva samples were obtained from 60 participants (45 [75%] women; median age 55 years [IQR 39-66]), who were undergoing either DST (42 [70%]) or CST (18 [30%]). A total of 10 (17%) saliva samples did not contain a sufficient sample for analysis during the first or second saliva collection (7 [12%] from DST group, and 3 [5%] from CST group).Among 53 patients undergoing DST, the median serum total cortisol was 1.3 mcg/dL [IQR 0.9-3], the median first SalF was 20 ng/dL [IQR 7-28], the median second SalF was 12 ng/dL [IQR 6-23], and the median variability was 11% [IQR 3-22%]. The median first SalE was 69 ng/dL [IQR 54-185], while the median second SalE was 63 ng/dL [IQR 56-178], with a median variability of 6% [IQR 4-10].In patients undergoing CST, peak median serum total cortisol was 20 mcg/dL [IQR 18-24], median first SalF was 809 ng/dL [IQR 536-1227], and median second SalF was 1063 ng/dL [IQR 667-1503], with the median variability of 14% [IQR 8-22]. The median first SalE was 2507 ng/dL [IQR1697-2966], while the median second SalE was 2485 ng/dL [IQR 1530-2976], with a median variability of 9% [IQR 3-12].When examining intra-individual variability of SalF, the variability was lowest in the middle tertile, corresponding to serum cortisol of 1.8-8.9 mcg/dL, at 9% [IQR 5-16]. Variability was higher in the lowest tertile (14% [IQR 0-52]) and the highest tertile (12% [IQR 6-16]). Overall, the variability of SalE was lower than that of SalF: 7% [IQR 4-13] in the lowest tertile, 5% [IQR 2-9] in the middle tertile, and 10% [IQR 4-12] in the highest tertile. Conclusion: We show that saliva sampling may impact the results, with 17% patients providing insufficient sample for analysis, and variability of 9-14% for SalF and 5-10% for SalE. Same time-point sampling-related variability should be considered in interpretation of SalF and SalE measurements. Presentation: Sunday, July 13, 2025

Abstract Disclosure: A. Prete: HRA Pharmaceuticals, Lundbeck, Diurnal. L. Adbi: None. J.T. Bain: None. F. Shaheen: None. O. Suntornlohanakul: None. E. Deflorenne: None. A. Blanchard: None. M. Nestola: None. C. Pamporaki: None. I. Tizianel: None. E. Nowak: None. J. Bertherat: None. D.A. Vassiliadi: None. I. Bancos: None. C.M. Dennedy: None. D. Kastelan: None. M. Fassnacht: None. P. Mulatero: None. U. Ambroziak: None. A. Tabarin: None. M. Quinkler: None. S. Puglisi: None. J. Deinum: None. G.Å. Ueland: None. L. Lenzini: None. F. Beuschlein: None. M. Reincke: None. F. Ceccato: None. G. Eisenhofer: None. S.M. Corsello: None. L. Amar: None. M. Zennaro: None. N. Karavitaki: None. A.E. Taylor: None. W. Arlt: None. Introduction: Twenty-four-hour urinary free cortisol is used to diagnose Cushing’s syndrome (CS); amongst its limitations is failure to differentiate ACTH-dependent CS (AD-CS) from ACTH-independent CS (AI-CS). We tested the performance of urine steroid metabolomics (USM), the computational analysis of 24-hour urine steroid metabolome data by machine learning, for the diagnosis and differential diagnosis of CS. Given the physiological diurnal rhythm of cortisol secretion and its loss in CS, we also hypothesised that the difference in glucocorticoid excretion between CS and controls should be higher during nighttime, thereby facilitating more sensitive detection of CS. Methods: 264 subjects completed a 24-hour urine collection (40 AD-CS, 103 AI-CS due to adrenocortical adenoma or hyperplasia, 121 healthy subjects). A subset of 52 individuals (13 CS, 39 healthy) provided a nighttime urine collection and a daytime urine collection. Mass spectrometry-based multi-steroid profiling was used to quantify the urinary excretion of 27 steroid metabolites. Data were analysed by generalised matrix learning vector quantisation (a prototype-based supervised machine learning approach), multiple linear regression adjusted for age, sex, and BMI, and multiple logistic regression adjusted for age, sex, and BMI. Results: Twenty-four-hour USM demonstrated very high accuracy in differentiating CS from healthy individuals (AUC-ROC 0.99, 95%CI 0.99-0.99), reflected by higher urinary excretion of glucocorticoid and glucocorticoid precursor metabolites in CS. USM yielded high accuracy in differentiating AD-CS from AI-CS (AUC-ROC 0.91, 95%CI 0.89-0.94), with androgen metabolites being the most discriminatory. We observed significant sex differences in steroid excretion in both healthy individuals and those with CS. Women exhibited markedly lower excretion of both glucocorticoids and mineralocorticoids compared to men: average glucocorticoid excretion was reduced by 43% in healthy women and 30% in CS women, while average mineralocorticoid excretion was 29% lower in healthy women and 51% lower in CS women (results adjusted for age and BMI). Timed steroid excretion in healthy individuals reflected the diurnal pattern of adrenal steroid secretion, with lower nighttime than daytime excretion of glucocorticoid metabolites. Nighttime glucocorticoid metabolite excretion (AUC-ROC 1.00, 95%CI 0.99-1.00) performed better than daytime (AUC-ROC 0.91, 95%CI 0.77-1.00) and 24-hour excretion (AUC-ROC 0.94, 95%CI 0.86-1.00) in separating CS cases from healthy individuals. Conclusions: USM is a non-invasive, one-step candidate test for the accurate diagnosis and differential diagnosis of CS. Timed nighttime urine collection leverages cortisol circadian rhythmicity and improves the diagnostic accuracy of the current reference standard 24-hour collection. Presentation: Sunday, July 13, 2025