Polyacrylonitrile/polypyrrole nanofiber-filled packed-fiber solid-phase extraction coupled with HPLC-FLD for matrix-interference-resistant determination of urinary pteridines and its application in autism spectrum disorder research.

Allergic rhinitis (AR) is a common chronic inflammatory condition of the nasal mucosa driven by IgE-mediated hypersensitivity, yet reliable biomarkers of systemic immune activity and oxidative stress remain limited despite involvement of Th2 cytokines, eosinophils, and macrophages. Neopterin (NPT) is a macrophage-derived marker of interferon-γ–induced immune activation and oxidative imbalance, but current plasma detection methods are expensive, or lack sufficient sensitivity for routine clinical use. Herein, a validated fluorescence-based method was developed for determination of plasma NPT using o-phthaldehyde derivatization in the presence of 2-mercaptoethanol under mildly alkaline conditions. The reaction formed a stable isoindole derivative with strong fluorescence (λ_ex = 335 nm, λ_em = 455 nm), increasing the quantum yield from 0.24 for native NPT to 0.65 for the NPT–OPA product. The method showed linearity from 1 to 20 ng/mL (r² = 0.9996), with a detection limit of 0.22 ng/mL and a quantification limit of 0.66 ng/mL. Accuracy ranged from 99.0% to 100.8%, and precision remained below 1.0%. No interference appeared from biopterin, folic acid, riboflavin, or xanthopterin, each contributing less than 5% of the NPT signal. Plasma NPT was measured in 26 AR patients and 26 healthy controls. AR patients showed elevated NPT concentrations (2.9 ± 0.7 ng/mL) compared to controls (1.5 ± 0.3 ng/mL, p < 0.001). NPT levels correlated with symptom severity (r = 0.44, p = 0.015) and eosinophil counts (r = 0.41, p = 0.022), indicating an association between immune activation and disease intensity. The fluorescence-based method provides a sensitive, selective, and rapid approach for plasma NPT quantification and supports NPT as a potential biomarker of immune activation and oxidative stress in AR.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-026-45216-7.

Neopterin (NPN), a pteridine derivative produced by activated monocytes and macrophages in response to interferon-γ, is a recognized biomarker of cellular immune activation, with elevated plasma levels reported in infections, autoimmune diseases, cardiovascular disorders, and cancers. There is an increasing attention given to its role in oxidative stress and vascular dysfunction in hypertension. In this work, a fluorescence-based method was developed and validated for the determination of NPN in plasma using derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). The reaction produced a stable fluorescent conjugate with a quantum yield of 0.61 compared to 0.21 for native NPN, resulting in enhanced signal intensity and improved selectivity. The method showed linearity over the concentration range of 1–20 ng/mL with a correlation coefficient of 0.9997. The limits of detection and quantification were 0.15 ng/mL and 0.45 ng/mL, respectively, with a mean recovery of 98.54%. Intra-day and inter-day relative standard deviations were below 2.5%, and interference from structurally related compounds was negligible (< 4%). The validated method was applied in a clinical case–control study of 52 participants (26 hypertensive patients and 26 normotensive controls), revealing significantly higher plasma NPN levels in hypertensive patients (3.0 ± 0.7 ng/mL) compared to controls (1.8 ± 0.4 ng/mL, p = 0.0002), with positive correlations to systolic (r = 0.48, p = 0.009) and diastolic blood pressure (r = 0.42, p = 0.025). These findings demonstrate that the developed method provides a sensitive and reliable approach for plasma NPN quantification and support its potential as a biomarker of hypertension diseases.

Selective and sensitive determination of neopterin in biological fluids using magnetic silica-supported molecularly-imprinted polymers.

Objective: Coronavirus disease 2019 (COVID-19) is associated with more severe clinical outcomes and increased mortality, particularly in individuals with comorbidities, such as hypertension and diabetes. This study aimed to evaluate the risk of developing coronary artery disease (CAD) about COVID-19 infection and vaccination status by measuring the serum levels of asymmetric dimethylarginine (ADMA), neopterin (NP), and vitamin D.Materials and methods: A total of 120 volunteers aged 30-65 years, presenting to a Chest Diseases Outpatient Clinic, were enrolled and categorized into four groups: COVID-19(+) vaccinated; COVID-19(+) unvaccinated; COVID-19(-) vaccinated; and COVID-19(-) unvaccinated. Routine biochemical parameters were assessed using an autoanalyzer. Serum ADMA and NP levels were quantified via enzyme-linked immunosorbent assay (ELISA), while vitamin D levels were obtained using a chromatography-based method.Results: According to the findings of our study, the serum levels of both ADMA and NP were elevated in individuals with COVID-19. While the increase in ADMA was statistically significant (p<0.05), the increase in NP was not (p>0.05). Furthermore, the lower, though not significant, vitamin D observed in COVID-19-positive participants is considered a significant finding. However, higher vitamin D was observed in vaccinated individuals compared to unvaccinated individuals, which was not statistically significant (p>0.05).Discussion and conclusion: The side effects of COVID-19 infection and vaccination continue to be a significant concern for all societies. Our study examined the association with the increased risk of CAD associated with this process. Our findings suggest that COVID-19 infection potentially influences CAD risk by affecting inflammatory and endothelial biomarkers, such as ADMA and NP. Simultaneous assessment of these markers can provide valuable information for cardiovascular risk profiling. Vaccination appears protective; it helps maintain higher vitamin D levels and is associated with a more controlled immune response, rather than increased risk. Including vitamin D status in this assessment may further clarify the interaction between immune function and vascular health.

Insulin resistance (IR) during pregnancy, even in women with normal body mass index (BMI), may affect maternal and fetal metabolic and immune status. This study aimed to evaluate neopterin (NPT), leptin, insulin, and ghrelin concentrations in maternal blood (MB) and umbilical cord blood (CB) in normoglycemic women with and without IR, all with normal BMI. Peripheral and cord blood was collected from 36 Caucasian women with term, uncomplicated vaginal deliveries. The participants were classified into control (n = 16; age = 30.81 ± 4.875 years) and IR (n = 20; age = 31.95 ± 4.979 years) groups based on a professional medical diagnosis. Anthropometric parameters were recorded, and metabolic/hormonal markers were measured using ELISA and RIA. NPT concentrations in CB were significantly higher in the IR group (p < 0.05), correlated positively with MB NPT levels (r = 0.3809, p < 0.05). A significantly higher concentration of both insulin and leptin was observed in the MB of women with IR compared to the control group (p < 0.0001), whereas in CB, only insulin concentration was significantly higher in the IR group than in healthy controls (p < 0.05). Ghrelin levels did not differ between the groups. Insulin resistance in non-obese pregnant women is associated with increased NPT concentration in CB, which may suggest fetal immune activation. However, defining the role of NTP as a metabolic "messenger" between mother and child requires further study.

Clinical and subclinical Shigella infections among children living in low- and middle-income countries (LMICs) have been associated with long-term adverse effects such as impaired linear growth. The mechanism for the impact of subclinical infections has been theorized to occur through contributions to environmental enteropathy (EE). While Shigella has previously been associated with biomarkers of EE at the time of infection, we evaluated whether this impact was sustained after infections, which would support EE being the mechanism for the effects of Shigella on growth. A prospective birth cohort study of 1,715 children living in 8 different LMICs was conducted. Over the course of 24 months, monthly non-diarrheal stool samples were analyzed for subclinical Shigella infections through quantitative PCR methods. EE was reflected by elevated concentrations of 3 fecal biomarkers: myeloperoxidase (MPO), neopterin (NEO), and alpha-1-antitrypsin (AAT). MPO concentrations were found to be significantly higher by 0.30 ln(nm/mL) (95% CI: 0.23, 0.37) in the initial month of Shigella detection among stools with subclinical Shigella infections. After the Shigella infection, MPO concentrations declined throughout the following 6 months, and concentrations were lower by 6 months post-infection [MPO 6-month difference: -0.16 ln(nm/mL) (95% CI: -0.26, -0.04)]. Subclinical Shigella infections had no effect on NEO concentration levels within the initial month of Shigella detection but did decrease post-infection. Subclinical Shigella infections had no effect on AAT concentration levels until 6 months post-infection [AAT difference: -0.13 ln(mg/g) (95% CI: -0.24, -0.03)]. These findings did not differ by antibiotic use around time of index infection. The impact of Shigella on biomarkers of EE was not sustained, suggesting the negative association between Shigella and growth could be explained by the accumulation of time-limited rather than persistent effects on inflammation.

PurposeTo study and compare the immune response and neopterin levels in the blood in experimental autoimmune uveitis (EAU).MethodsA model of EAU was created in 30 Chinchilla rabbits. Intravenous and intravitreal injections of normal horse serum were administered for this purpose. Clinical examinations and blood tests were conducted on days 3, 7, 10, 14, and 21. The blood investigation included the determination of neopterin (NP) level, white blood cell counts, lymphocytes, CD3+, CD4+, CD8+, and CD16+.ResultsThe peak in white blood cell count was observed on days 7 and 10 (6.4 ± 0.4 g/L and 6.0 ± 0.3 g/L, respectively), lymphocytes on day 3 (68.3% ± 2.4%, 3.0 ± 0.2 g/L), CD3+ on day 7 (64.9% ± 3.1%, 2,032.5 ± 91.2 cells/μL), CD4+ and CD16+ on day 10 (54.6% ± 3.8%, 2,462.3 ± 60.7 cells/μL and 21.8% ± 1.8%, 691.2 ± 37.1 cells/μL, respectively). All these values did not return to the initial ones. There was a gradual decrease in the CD8+ count from day 3 (12.5% ± 1.1%, 142.8 ± 9.1 cells/μL) with a subsequent gradual return towards normal levels by day 21. NP levels incresed on day 3 (5.2 ± 0.7 nmol/L), sustained on day 7 (5.2 ± 0.8 nmol/L), and started to decrease from day 10 (4.25 ± 1.7 nmol/L) to 2.3 ± 0.5 nmol/L on day 21. The highest correlation was observed between clinical manifestations and NP with a correlation coeffient of 0.799 (95% confidence interval, 0.719–0.858), which was significantly stronger (p < 0.05) than the correlations with other immune response markers.ConclusionsDuring the modeling of EAU, there is an active immune response and a rapid reaction of NP on inflammation. NP is a significantly more sensitive marker of intraocular inflammation than the immune response. It can serve as a predictor of the onset and development of EAU.

Cancer is a state of immunological imbalance associated with chronic inflammation and local immunosuppression. Introducing immune checkpoint inhibitors was a breakthrough in cancer treatment. However, the treatment outcomes remain unsatisfactory, and many patients still progress after the initial response. The study aimed to assess whether serum neopterin (NEO), an indicator of cellular immune activation, could be used as a predictor of the long-term benefits of drugs blocking the programmed cell death protein 1 pathway (anti-PD-1/PD-L1 drugs). We enrolled 103 patients with non-small cell lung cancer (NSCLC) treated with anti-PD-1/PD-L1s. Serum was collected at baseline and at the end of each treatment cycle for the first three months of immunotherapy. NEO concentrations were determined with a validated high-performance liquid chromatography assay and correlated with treatment outcomes. Low-NEO status (i.e., serum NEO levels ≤ 71.65 nM at the end of the 3rd treatment cycle and ≤ 66.84 nM at the end of the 4th treatment cycle) increased the odds of ≥ 12-month benefits (odds ratio, OR = 11.70, p < 0.001), and decreased the hazard of NSCLC progression (hazard ratio, HR = 0.327, p < 0.001) and treatment failure (adjusted HR = 0.450, p < 0.05). Patients with low-NEO status had three times longer progression-free survival (PFS, 17.3 vs. 5.9 months) and three times longer time to treatment failure (TTF, 16.3 vs. 5.5 months) compared to other patients. Baseline NEO levels could not discriminate between patients who had and lacked the long-term benefits of treatment. In conclusion, the on-treatment serum NEO concentrations could be a biomarker of the long-term benefits of the anti-PD-1/PD-L1 treatment in advanced NSCLC.

Neopterin (NEO) is an inflammatory biomarker with proposed diagnostic value in cardiovascular diseases. Some correlations have been discovered between NEO levels and the incidence, severity, and adverse outcomes of heart failure (HF). However, there are discrepancies in the results reported in the literature. We conducted a systematic review and meta-analysis of studies comparing urinary and blood NEO concentrations between individuals with HF, cardiac insufficiency, or dilated cardiomyopathy (DCM) with control groups or those monitoring the role of NEO concentrations as a predictive marker of adverse outcomes in HF patients. A total of 24 studies that met the inclusion criteria were reviewed. The studies demonstrated the alteration of NEO in blood or urine samples in subjects with HF, cardiac insufficiency, or DCM compared with control groups. Also, reviewing the studies suggested a link between reduced ejection fraction, higher NYHA classes, and a higher risk of adverse cardiac outcomes with increased NEO levels. The meta-analysis of three studies revealed a significant increase in serum NEO levels in HF cases compared to that in healthy controls with an effect size of 3.72 (95 % CI 0.16 to 7.28; p = 0.04). Meta-analysis demonstrated a significant difference between serum NEO levels of HF cases and healthy subjects. This evidence implies the potential of serum NEO as a valuable diagnostic biomarker in HF patients. Also, the review of the studies revealed the prognostic potential of NEO. Further research is required to assess the usefulness of NEO as a diagnostic/prognostic biomarker for HF.

The increased burden of non-communicable diseases (NCDs) is fueled by lifestyle factors including diet. This cross-sectional study explored among Tanzanian adults whether unhealthy dietary patterns are associated with intestinal and systemic inflammation which could increase the risk of NCDs. The study included 574 participants, with both diet and inflammatory markers data. Dietary patterns were derived using principal component analysis and reduced rank regression, revealing three main patterns: vegetable-rich, vegetable-poor, and carbohydrate-dense diets. Fecal myeloperoxidase (MPO) and neopterin (NEO) were markers of intestinal inflammation whereas plasma lipopolysaccharide-binding protein (LBP) and C-reactive protein (CRP) were assessed as markers of systemic inflammation. Ordinal logistic regression was used to assess associations between terciles of dietary patterns and quintiles of the inflammatory markers adjusting for potential confounders. High adherence to a vegetable-poor dietary pattern was associated with elevated MPO (adjusted OR, 1.7 95% CI 1.1, 2.8). NEO tended to be higher in people with high adherence to both vegetable-poor pattern (adjusted OR, 2.6 95% CI 1.0, 6.4) and vegetable-rich pattern (adjusted OR, 2.7, 95% CI 1.1, 6.5). No associations were found between dietary patterns and systemic inflammation markers (LBP and CRP). We found links between dietary vegetable intake and intestinal inflammation but not systemic inflammation. However, the cross-sectional nature of the study limits establishing causality and the sample size for some variables may have been inadequate, emphasizing the need for further studies to understand how dietary habits influence inflammation in this population.

The increased burden of non-communicable diseases (NCDs) is fueled by lifestyle factors including diet. This cross-sectional study explored among Tanzanian adults whether unhealthy dietary patterns are associated with intestinal and systemic inflammation which could increase the risk of NCDs. The study included 574 participants, with both diet and inflammatory markers data. Dietary patterns were derived using principal component analysis and reduced rank regression, revealing three main patterns: vegetable-rich, vegetable-poor, and carbohydrate-dense diets. Fecal myeloperoxidase (MPO) and neopterin (NEO) were markers of intestinal inflammation whereas plasma lipopolysaccharide-binding protein (LBP) and C-reactive protein (CRP) were assessed as markers of systemic inflammation. Ordinal logistic regression was used to assess associations between terciles of dietary patterns and quintiles of the inflammatory markers adjusting for potential confounders. High adherence to a vegetable-poor dietary pattern was associated with elevated MPO (adjusted OR, 1.7 95% CI 1.1, 2.8). NEO tended to be higher in people with high adherence to both vegetable-poor pattern (adjusted OR, 2.6 95% CI 1.0, 6.4) and vegetable-rich pattern (adjusted OR, 2.7, 95% CI 1.1, 6.5). No associations were found between dietary patterns and systemic inflammation markers (LBP and CRP). We found links between dietary vegetable intake and intestinal inflammation but not systemic inflammation. However, the cross-sectional nature of the study limits establishing causality and the sample size for some variables may have been inadequate, emphasizing the need for further studies to understand how dietary habits influence inflammation in this population.

BackgroundValidated biomarkers could catalyze environmental enteric dysfunction (EED) research. ObjectivesLeveraging an EED histology scoring system, this multicountry analysis examined biomarker associations with duodenal histology features among children with EED. We also examined differences in 2-h compared with 1-h urine collections in the lactulose rhamnose (LR) dual sugar test. MethodsThree cohorts of undernourished children unresponsive to nutrition intervention underwent esophagogastroduodenoscopy and duodenal biopsies. Histopathology scores were compared to fecal calprotectin (CAL), myeloperoxidase (MPO), neopterin (NEO), and urinary LR ratio and lactulose percentage recovery. Log-transformed biomarkers were used in linear regressions adjusted for age, center, and sample collection–biopsy time interval in multivariable models. ResultsData on >1 biomarker were available for 120 Bangladeshi (CAL, MPO, NEO, and LR), 63 Pakistani (MPO, NEO, and LR), and 63 Zambian children (CAL). Median age at endoscopy was similar (19 mo) across centers. Median sample collection prior to endoscopy was consistent with each center’s study design: 2 wk in Bangladesh (urine and stool) and Zambia (stool), and 6 (urine) and 11 (stool) mo in Pakistan. In multivariable models, intraepithelial lymphocytes were associated with CAL (exponentiated [exp.] coefficient: 1.19; 95% confidence interval [CI]: 1, 1.41), intramucosal Brunner’s glands with MPO (exp. coefficient: 1.33; 95% CI: 1.05, 1.69) and NEO (exp. coefficient: 1.37; 95% CI: 1.1, 1.7), and chronic inflammation with NEO (exp. coefficient: 1.61; 95% CI: 1.17, 2.17). Intraepithelial lymphocytes were associated with lactulose % recovery (exp. coefficient: 1.22; 95% CI: 1.05, 1.41). LR recovery was substantially lower in 1-h collections than in 2-h collections. ConclusionsFour commonly used markers of enteric dysfunction were associated with specific histologic features. One-hour urine collection may be insufficient to reflect small bowel permeability in LR testing. While acknowledging the challenges with obtaining relevant tissue, these findings form the basis for further EED biomarker validation research.

Exercise-induced inflammation can influence iron metabolism. Conversely, the effects of vitamin D3, which possesses anti-inflammatory properties, on ultramarathon-induced heart damage and changes in iron metabolism have not been investigated. Thirty-five healthy long-distance semi-amateur runners were divided into two groups: one group received 150,000 IU of vitamin D3 24 h prior to a race (n = 16), while the other group received a placebo (n = 19). Serum iron, hepcidin (HPC), ferritin (FER), erythroferrone (ERFE), erythropoietin (EPO), neopterin (NPT), and cardiac troponin T (cTnT) levels were assessed. A considerable effect of ultramarathon running on all examined biochemical markers was observed, with a significant rise in serum levels of ERFE, EPO, HPC, NPT, and cTnT detected immediately post-race, irrespective of the group factor. Vitamin D3 supplementation showed a notable interaction with the UM, specifically in EPO and cTnT, with no other additional changes in the other analysed markers. In addition to the correlation between baseline FER and post-run ERFE, HPC was modified by vitamin D. The ultramarathon significantly influenced the EPO/ERFE/HPC axis; however, a single substantial dose of vitamin D3 had an effect only on EPO, which was associated with the lower heart damage marker cTnT after the run.

Background/Objectives: As COVID-19 can be severe, early predictive markers of both severity and onset of secondary bacterial infections are needed. This study first examined changes over time in the levels of plasma neopterin (NP) and biopterins (BPs), among others, in patients with COVID-19 and then in those with secondary bacterial infection complications. Methods: Fifty-two patients with COVID-19 admitted to two tertiary care centers were included. They were divided into a severe group (intubated + mechanical ventilation) (n = 10) and a moderate group (non-intubated + oxygen administration) (n = 42), and changes over time in plasma NP, plasma BPs, IFN-γ, lymphocyte count, CRP, and IL-6 were investigated. Four of the patients in the severe group (n = 10) developed secondary bacterial infections during treatment. Plasma NP and plasma BPs of patients with bacterial sepsis (no viral infection) (n = 25) were also examined. Results: The plasma NP, IL-6, CRP, and SOFA levels were significantly higher in the severe group, while the IFN-γ level and lymphocyte count were significantly lower. The higher plasma NP in the severe group persisted only up to 1 week after symptom onset. The plasma BPs were higher in complications of bacterial infection. Conclusions: The timing of sample collection is important for assessing severity through plasma NP, while plasma BPs may be a useful diagnostic tool for identifying the development of secondary bacterial infection in patients with COVID-19. Further investigation is needed to clarify the mechanism by which NP and BPs, which are involved in the same biosynthetic pathway, are differentially activated depending on the type of pathogen.

Determine the saliva and serum levels of neopterin (NP) and 7,8-dihydroneopterin (7,8NP) in periodontitis patients and to reveal the relationship of these data with clinical periodontal parameters. Twenty-three patients with stage III/grade B periodontitis and 23 periodontally healthy individuals were included. Clinical periodontal measurements were recorded (plaque index, pocket depth, clinical attachment loss & bleeding on probing). Saliva and serum levels of NP and 7,8NP were analyzed by high-performance liquid chromatography. Saliva NP, 7,8NP and Total Neopterin (TNP) levels were significantly elevated in the periodontitis than the control group (p < 0.001).ROC analyses of saliva NP, 7,8NP and TNP yielded areas under the curves of 0.873-0.938 for discriminating periodontitis from health, and saliva TNP was found the most accurate biomarker (AUC = 0.938).There was no significant difference among the periodontitis and control groups for saliva TNP/NP and TNP/7,8NP ratios and serum NP, 7,8NP and TNP levels (p > 0.05). Increased saliva TNP, NP and 7,8NP levels in periodontitis may suggest these biomarkers are regulating immune activation and oxidative stress mechanism in periodontal inflammation. Additionally, together with these results, equivalence of the TNP/NP ratio in intergroups may suggest that the effects of immune activation and oxidative stress mechanisms are equal in the periodontitis.

Exploring oxidative stress, immunological and metabolic biomarkers in dairy cows with postpartum pyometra.

Altered neopterin and IDO in kynurenine metabolism based on LC-MS/MS metabolomics study: Novel therapeutic checkpoints for type 2 diabetes mellitus

Background and objectiveEndothelial dysfunction has been widely recognized in chronic airway diseases, including chronic obstructive pulmonary disease (COPD) and asthma; however, it remains unclear in asthma-COPD overlap (ACO). Neopterin (NP), a metabolite of guanosine triphosphate, is a novel biomarker for identifying the increased risk of adverse cardiovascular events. This study aims to investigate the association of NP with endothelial dysfunction and impaired lung function in COPD, asthma, and ACO patients.MethodsA total of 77 subjects were prospectively recruited. All the participants underwent lung function test, endothelial function evaluation, including pulse wave velocity (PWV) and flow-mediated dilation (FMD), and blood sample detection. Moreover, the effect of NP on endothelial cells (ECs) in anoxic environments was assessed in vitro.ResultsEndothelial function was significantly decreased in the COPD and ACO patients compared with that in the healthy controls (P < 0.05). Forced expiratory volume in 1 s (FEV1) was negatively correlated with PWV and positively correlated with FMD (P < 0.05). NP was significantly increased in patients with chronic respiratory diseases compared with that in the control group, with COPD being the highest, followed by asthma, and ACO as the last (P < 0.05). The plasma level of NP exhibited negative correlations with FEV1 and positive correlations with PWV (P < 0.05). In vitro, a high level of NP increased the reactive oxygen species (ROS) and decreased the mitochondrial membrane potential (ΔΨm) of ECs dose-dependently in a hypoxic environment (P < 0.05).ConclusionNP was related to disease severity of chronic airway diseases and involved in the pathogenesis of endothelial dysfunction. A high NP level may contribute to endothelial dysfunction by increasing the oxidative stress of ECs dose-dependently in a hypoxic environment. Our findings may provide a novel evaluation and therapeutic target for endothelial dysfunction related to chronic airway diseases.

Aim: Graves' disease is a disease with an autoimmune basis in which the synthesis and release of thyroid hormone from the thyroid gland increases. Interferon-gamma (IFN-γ) released from activated T lymphocytes causes macrophages to produce neopterin (NPT), increasing its concentration in serum and other body fluids. There is a relationship between NPT and the production of free oxygen radicals by these cells. In this study, it was aimed to measure serum NPT levels in individuals with Graves' disease. Material and Method: The study included 13 newly diagnosed Graves' patients (neopterin levels were measured at the time of first diagnosis and at the 3rd month of treatment) and 16 Graves' patients who were followed up in endocrinology outpatient clinics for at least one year. NPT levels of 23 healthy individuals without any disease were taken as the control group. Free triiodothyronine (T3), free thyroxine (T4), thyroglobulin, and thyroid stimulating hormone (TSH) levels were measured in the blood samples of the participants. Results: Serum NPT levels were found to be higher in Graves' patients compared to the control group (6.66 nmol/L in newly diagnosed patients, 9.24 nmol/L in patients at the 3rd month of treatment, 10.68 nmol/L in patients followed for one year or more, 1.44 nmol/L in the control group, respectively, p