Search

Objective: Craniopharyngiomas (CPG) have complex treatment challenges due to their proximity to vital structures, surgical and radiotherapeutic complexities, and the tendency for recurrence. The aim of this study was to identify the prevalence of endocrine and metabolic comorbidities observed during initial diagnosis and long-term follow-up in a nationwide cohort of pediatric CPG patients. A further aim was to highlight the difficulties associated with CPG management., Methods: Sixteen centers entered CPG patients into the ÇEDD NET data system. The clinical and laboratory characteristics at presentation, administered treatments, accompanying endocrine, metabolic, and other system involvements, and the patient’s follow-up features were evaluated., Results: Of the 152 evaluated patients, 64 (42.1%) were female. At presentation, the mean age was 9.1±3.67, ranging from 1.46 to 16.92, years. The most common complaints at presentation were headache (68.4%), vision problems (42%), short stature (15%), and nausea and vomiting (7%). The surgical procedures were gross total resection (GTR) in 97 (63.8%) and subtotal resection in 55 (36.2%). Radiotherapy (RT) was initiated in 11.8% of the patients. Histopathological examination reported 92% were adamantinamatous type and 8% were papillary type. Postoperatively, hormone abnormalities consisted of thyroid-stimulating hormone (92.1%), adrenocorticotropic hormone (81%), antidiuretic hormone (79%), growth hormone (65.1%), and gonadotropin (43.4%) deficiencies. Recombinant growth hormone treatment (rhGH) was initiated in 27 (17.8%). The study showed hesitancy among physicians regarding rhGH. The median survival without relapse was 2.2 years. Median (range) time of relapse was 1.82 (0.13-10.35) years. Relapse was related to longer followups and reduced GTR rates. The median follow-up time was 3.13 years. Among the last follow-up visits, the prevalence of obesity was 38%, but of these, 46.5% were already obese at diagnosis. However, 20% who were not obese at baseline became obese on follow-up. Permanent visual impairment was observed in 26 (17.1%), neurological deficits in 13 (8.5%) and diabetes mellitus in 5 (3.3%) patients., Conclusion: Recurrence was predominantly due to incomplete resection and the low rate of postoperative RT. Challenges emerged for multidisciplinary regular follow ups. It is suggested that early interventions, such as dietary restrictions and increased exercise to prevent obesity, be implemented., Competing Interests: Conflict of Interest: Three authors of this article, Damla Gökşen, Korcan Demir, Samim Özen, are member of the Editorial Board of the Journal of Clinical Research in Pediatric Endocrinology. However, they did not take part in any stage of the editorial decision of the manuscript. The editors who evaluated this manuscript are from different institutions. The other authors declared no conflict of interest., (©Copyright 2024 by Turkish Society for Pediatric Endocrinology and Diabetes / The Journal of Clinical Research in Pediatric Endocrinology published by Galenos Publishing House.)

Delayed puberty is defined as the lack of development of secondary sex characteristics in childhood. Based on a review of the literature, delayed puberty can be divided into three main categories: (i) hypergonadotropic hypogonadism (congenital and acquired), (ii) permanent hypogonadotropic hypogonadism (congenital and acquired), and (iii) transient hypogonadotropic hypogonadism [constitutional delay of growth and puberty (CDGP) and functional hypogonadotropic hypogonadism (FHH)]. CDGP is the most common cause of hypogonadism in both males and females, accounting for 60% and 30% respectively. Testosterone is the primary treatment for male hypogonadism, while estrogen and progesterone are used for female hypogonadism. However, in recent years, physiological induction therapy protocols such as human chorionic gonadotropin (hCG) monotherapy, hCG + Follicle-stimulating hormone combined therapy, and gonadotropin releasing hormone infusion have been recommended for the treatment of hypogonadotropic hypogonadism to increase long-term fertility success. There is no clear consensus on treatment protocols for physiological induction treatment and its effect on fertility. This review will discuss the clinical approach to hypogonadism, as well as traditional and physiological induction protocols.

Introduction: Aromatase inhibitors (AIs) are increasingly used in children and adolescents to augment adult height. The aim of this study was to investigate the effects AIs have on cardiac morphology, functions and their relation to several metabolic parameters in adolescent boys., Methods: Three groups matched for sex (boys, n = 67), age (median age 13.5 years), weight, height, body mass index, and puberty stages were enrolled: (i) Group 1: 23 patients using AIs (only AI (n = 6) or in combination with growth hormone (GH) (n = 17)) for at least 6 months; (ii) Group 2: 22 patients using only GH, and (iii) Group 3: 22 healthy boys. Two-dimensional, M-mode conventional Doppler and tissue Doppler examinations of the left ventricle (LV) were performed. Bioelectrical bioimpedance analyses was conducted and follicle-stimulating hormone, luteinizing hormone, total testosterone, lipid, and hemogram parameters were obtained., Results: Patients in Group 1 had significantly higher serum total testosterone (p < 0.001) and hemoglobin (p < 0.001) levels, fat free mass (p = 0.005), LV mass (LVM) (p = 0.002), as well as increased LV posterior wall diameter (LVPWD) (p = 0.002), interventricular septum diameter (IVSD) (p = 0.019), and myocardial systolic wave velocity (Sm) (p = 0.020) compared to the two other control groups. No significant differences were observed in terms of diastolic and systolic functions and lipid profiles (p > 0.05). There were positive correlations between total testosterone, hemoglobin levels, LVM, LVPWD and IVSD (p < 0.05)., Conclusion: Increased LVM, LVPWD, IVSD and Sm of patients receiving AI therapy in comparison to the control groups, and the significant correlations of these parameters with total testosterone and hemoglobin levels were determined as potential side effects of AIs. These findings emphasize the need of routine cardiac follow-up in patients using AIs., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Primary pigmented nodular adrenocortical disease (PPNAD) is a rare genetic disease mainly associated with Carney complex (CNC), which is caused by germline mutations of the regulatory subunit type 1A (RIα) of the cAMP-dependent protein kinase (PRKAR1A) gene. We report three cases suffering from CNC with unique features in diagnosis and follow-up. All cases had obesity and a cushingoid appearance and exhibited laboratory characteristics of hypercortisolism. However biochemical and radiological examinations initially suggested Cushing's disease in one case . All of the cases were treated surgically; two of them underwent bilateral adrenalectomy at once, one of them had unilateral adrenalectomy at first but required contralateral adrenalectomy after nine months. Contrary to what is usually known regarding PPNAD, the adrenal glands of two cases (case 2 and 3) had a macronodular morphology. Genetic analyses revealed pathogenic variants in PRKAR1A (case 1: c.440+5 G>A, not reported in the literature; cases 2 and 3: c.349G>T, p.V117F). One case developed Hodgkin lymphoma five year after adrenalectomy, this association was not previously reported with CNC. The findings of these families provide important information for a better understanding of the genetic pathogenesis, diagnosis, and clinical management of CNC. Hodgkin lymphoma may be a component of CNC.

Aim: We aimed to describe the clinical characteristics of patients with congenital combined pituitary hormone deficiency (CPHD) and evaluate the first-year growth responses of individuals with CPHD and isolated growth hormone deficiency (IGHD) in order to establish the influence of other hormone deficiencies on growth response., Patients and Methods: This retrospective study was conducted in four tertiary care centers in Turkey. The records of patients diagnosed with CPHD (n=39) and severe IGHD (n=50) were collected. Cases with acquired lesions or chronic diseases were not included in the study. Data are presented as median (interquartile range)., Results: Among 39 patients (13 females; 33%) with a diagnosis of CPHD, the majority of patients (64%) presented initially with combined deficits at baseline examination, whereas isolated deficiencies (36%) were less prevalent. Among all patients with GH deficiency, TSH, ACTH, FSH/LH, and ADH deficiencies were present in 94%, 74%, 44%, and 9% of patients, respectively. Patients with CPHD were diagnosed at a younger age (4.9 (8.4) vs. 11.6 (4.1), p<0.001, respectively) and had lower peak GH concentrations (0.4 (1.8) vs. 3.7 (2.9), p<0.001, respectively) than patients with IGHD. Patients with IGHD and CPHD had similar first-year growth responses (Δheight SD score of 0.55 (0.63) vs. 0.76 (0.71), respectively, p=0.45)., Conclusions: We established the nature and timing of numerous hormonal deficits emerging over time. We also identified that the existence of CPHD did not hinder growth response., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Purpose: The aim of the present study was to determine the efficiency of three different predictive models [Bayley-Pinneau (BP), Roche-Wainer-Thissen (RWT), and Tanner-Whitehouse 2 (TW2)] by comparing their predictions with near-adult height data of girls receiving gonadotropin-releasing hormone agonist (GnRHa) therapy., Methods: Clinical findings were retrospectively analyzed. Bone ages obtained before treatment were evaluated from left hand and wrist radiographs by three researchers. Predicted adult height (PAH) was calculated using the BP, RWT, and TW2 methods for each patient at the beginning of therapy., Results: The median age at diagnosis of the 48 patients included in the study was 8.8 (8.9-9.3) years. There was no significant difference between the mean bone ages evaluated separately with the Greulich-Pyle atlas and the TW3-RUS method (p=0.34). Among the PAH methods, only PAH measured by the BP method was very close to and no different from near adult height (NAH) [159.8±6.3 vs. 158.8±9.3 cm. p=0.3; (-0.5±1.1) vs. (-0.7±1.6) standard deviation score, p=0.1]. Accordingly, the BP method was found to be the most accurate prediction tool in girls with puberty treated with GnRHa., Conclusion: The BP method is more effective at predicting adult height than the RWT and TW2 methods in female patients who will receive GnRHa treatment., (© 2023. The Author(s), under exclusive licence to Hellenic Endocrine Society.)

Objective: Both body weight (BW)- and body surface area (BSA)-based dosing regimens have been recommended for growth hormone (rhGH) replacement. The aim was to compare the two regimens to determine if either resulted in inadequate treatment depending on anthropometric factors., Methods: The retrospective study included children diagnosed with idiopathic isolated growth hormone deficiency. BW-based dosing in mcg/kg/day was converted to BSA in mg/m2/day to determine the equivalent amounts of the given rhGH. Those with a BW-to-BSA ratio of more than 1 were allocated to the “relatively over-dosed group”, while the remaining patients with a ratio of less than 1 were assigned to the “relatively under-dosed” group. Patients with a height gain greater than 0.5 standard deviation score (SDS) at the end of one year were classified as the height gain at goal (HAG), whereas those with a height gain of less than 0.5 SDS were assigned as the height gain not at goal (NHAG)., Results: The study included 60 patients (18 girls, 30%). Thirty-six (60%) patients were classified as HAG. The ratio of dosing based on BW-to-BSA was positively correlated both with the ages and body mass index (BMI) levels of the patients, leveling off at the age of 11 at a BMI of 18 kg/m2. The relative dose estimations (over- and under-dosed groups) differed significantly between the patients classified as HAG or NHAG. Fifty-six percent of NHAG compared to 44% of HAG patients received relatively higher doses, while 79% of HAG compared to 21% of NHAG received relatively lower doses (p=0.006). When the patients were subdivided according to their pubertal status, higher doses were administrated mostly to the pubertal patients in both the NHAG and HAG groups. In the pre-pubertal age group, 73% of NHAG compared to 27% of HAG received relatively higher doses, while 25% of NHAG compared to 75% of HAG received relatively lower doses (p=0.01)., Conclusion: Dosing based on BW may be preferable in both prepubertal and pubertal children who do not show adequate growth responses. In prepubertal children, relatively lower doses calculated based on BW rather than BSA provide similar efficacy at lower costs.

Objective: The aim was to evaluate the adverse events seen after Coronavirus disease-2019 (COVID-19) vaccination in pediatric patients with diagnosed endocrinological problems and to compare them with healthy controls., Methods: In this cross-sectional study, patients aged 12-18 years who attended a single department between January and May 2022 and were followed up for at least six months due to endocrine diseases, and healthy subjects in the same age group, all of whom had received a COVID-19 vaccine [BNT162b2 mRNA or inactivated vaccine] were included. Adverse events experienced after the vaccination were evaluated by questionnaire., Results: A total of 160 subjects (85 patients, 75 healthy controls) with a median (25-75p) age of 15.5 (14.1-16.9) years were included. The frequency of adverse events was higher in those vaccinated with the mRNA vaccine compared to the inactivated one after the first dose (p=0.015). The incidence of adverse events observed after the first and second doses of both COVID-19 vaccines was similar in the patient and control groups (p=0.879 and p=0.495, respectively), with local reactions being the most common. The frequency of adverse events was similar among the patients who did or did not receive any endocrinological treatment (p>0.05). The incidence and severity of systemic reactions were similar to those in healthy subjects for both vaccine doses, regardless of the underlying diagnosis, autoimmunity state, or treatment regimen used in patients with endocrine diseases., Conclusion: The incidence and severity of adverse events associated with COVID-19 vaccinations in adolescents with endocrinological disorders were similar to healthy subjects, in the early post-vaccination period.

Context: Homozygous leptin (LEP) and leptin receptor (LEPR) variants lead to childhood-onset obesity., Objective: To present new cases with LEP and LEPR deficiency, report the long-term follow-up of previously described patients, and to define, based on all reported cases in literature, genotype-phenotype relationships., Methods: Our cohort included 18 patients (LEP = 11, LEPR = 7), 8 of whom had been previously reported. A systematic literature review was conducted in July 2022. Forty-two of 47 studies on LEP/LEPR were selected., Results: Of 10 new cases, 2 novel pathogenic variants were identified in LEP (c.16delC) and LEPR (c.40 + 5G > C). Eleven patients with LEP deficiency received metreleptin, 4 of whom had been treated for over 20 years. One patient developed loss of efficacy associated with neutralizing antibody development. Of 152 patients, including 134 cases from the literature review in addition to our cases, frameshift variants were the most common (48%) in LEP and missense variants (35%) in LEPR. Patients with LEP deficiency were diagnosed at a younger age [3 (9) vs 7 (13) years, P = .02] and had a higher median body mass index (BMI) SD score [3.1 (2) vs 2.8 (1) kg/m2, P = 0.02], which was more closely associated with frameshift variants (P = .02). Patients with LEP deficiency were more likely to have hyperinsulinemia (P = .02)., Conclusion: Frameshift variants were more common in patients with LEP deficiency whereas missense variants were more common in LEPR deficiency. Patients with LEP deficiency were identified at younger ages, had higher BMI SD scores, and had higher rates of hyperinsulinemia than patients with LEPR deficiency. Eleven patients benefitted from long-term metreleptin, with 1 losing efficacy due to neutralizing antibodies., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objectives: This study aimed to determine the prevalence and predictors of euthyroid sick syndrome (ESS) in pediatric intensive care, and to establish a link between thyroid function tests and mortality., Methods: Between January 2015 and March 2020, children admitted to our pediatric intensive care unit (PICU) and tested for free triiodothyronine (fT3), free thyroxine (fT4), and thyrotropin (TSH) levels were included. Patients with decreased fT3, with normal or decreased fT4, and normal or decreased TSH levels were assigned to the ESS group. The association between biochemical indicators and ESS, as well as the relationship between fT3 and mortality, were examined., Results: A total of 141 (36%) of 386 children included to study were classified in the ESS group. The ESS group had a higher rate of 28-day mortality (12 [8.5%] vs. 9 [3.7%]). Blood urea nitrogen (BUN), albumin, platelet, lactate, and pediatric index of mortality 3 [PIM3 (%)] were significantly associated with ESS (odds ratios in order: 1.024, 0.422, 0.729, 1.208, 1.013). Multivariate regression analysis showed that BUN, albumin, platelet, and lactate were independently associated with ESS progression. The area under curve (AUC [95%CI]) for fT3 was 0.644 (0.555-0.789) to detect mortality. Children with a fT3 level lower than 2.31 pg/mL had significantly higher 28-day mortality (log rank test, p=0.001)., Conclusions: Our study identified BUN, albumin, lactate, and platelet count as independent risk factors for ESS progression in children. Furthermore, our findings indicated a correlation between fT3 and mortality, which makes fT3 an ideal candidate to be included in mortality indices., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Introduction: SLC29A3 spectrum disorder is an autosomal, recessively inherited, autoinflammatory, multisystem disorder characterized by distinctive cutaneous features, including hyperpigmentation or hypertrichosis, hepatosplenomegaly, hearing loss, cardiac anomalies, hypogonadism, short stature, and insulin-dependent diabetes., Case Presentation: Herein, we report a 6-year-old boy who presented with features resembling type 1 diabetes mellitus, but his clinical course was complicated by IgA nephropathy, pure red cell aplasia, and recurrent febrile episodes. The patient was tested for the presence of pathogenic variants in 53 genes related to monogenic diabetes and found to be compound heterozygous for two SLC29A3 pathogenic variants (p. Arg386Gln and p. Leu298fs)., Conclusion: This case demonstrated that SLC29A3 spectrum disorder should be included in the differential diagnosis of diabetes with atypical comorbidities, even when the distinctive dermatological hallmarks of SLC29A3 spectrum disorder are entirely absent., (© 2022. Hellenic Endocrine Society.)

Objective: Early puberty is development of secondary sex characteristics earlier than the expected normal age range. We subjectively observed an increased frequency of early puberty during the Coronavirus disease-2019 (COVID-19) lockdown and aimed to show the clinical, demographic characteristics of the cases and the change in its incidence., Methods: Female patients with central precocious puberty (CPP, n=28) and rapidly progressive early puberty (RPEP, n=61), presenting to our clinic before (January 2019-March 2020) and during the COVID-19 pandemic (April 2020-June 2021) were included., Results: Among 28 CPP cases, six (21%) presented before the pandemic lockdown, whereas 22 (79%) were diagnosed during the COVID-19 pandemic lockdown. While RPEP was seen in 16 (26%) patients before the pandemic, 45 (74%) patients were diagnosed during the lockdown period. Presentation with menarche was seen in 15 RPEP patients; two (13%) were in the prepandemic period and 13 (87%) were in the lockdown period. Chronological age, bone age, bone age to chronological age ratio, height, weight, and body mass index standard deviation scores of patients with RPEP and CPP were similar between the prepandemic and pandemic period., Conclusion: In this cohort, the frequency of CPP and RPP cases were significantly (p<0.001) increased during the COVID-19 pandemic, possibly due to environmental changes.

Objective: Since there is no gold standard laboratory variable for adjustment of treatment in congenital adrenal hyperplasia (CAH), the aim was to assess the use of a 4-hour profile of serum 17-hydroxyprogesterone (17-OHP) to determine the most appropriate sample time and level of 17-OHP in predicting the metabolic control and evaluate the role of sex hormone-binding globulin (SHBG) in hyperandrogenemia., Methods: This study included children with salt-wasting CAH. Measurements for 17-OHP and cortisol were made from samples obtained before and 1, 2, and 4 hours after the morning dose of hydrocortisone. Patients were designated to have poor metabolic control when androstenedione levels according to age and sex-specific reference intervals were high and annual height standard deviation score (SDS) changes were ≥0.5., Results: The study cohort was 16 children (9 girls) with a median age of 7-years old. Premedication 17-OHP levels were strongly correlated with 17-OHP levels 1, 2, and 4 hours after the morning dose (r s =0.929, p<0.01; r s =0.943, p<0.01; r s =0.835, p<0.01, respectively). 17-OHP profiles (0, 1, 2, 4 hours) of poor (n=6) and good (n=10) metabolically controlled cases were similar. Among the patients with poor metabolic control, two cases had 17-OHP levels <2 ng/mL at all times. The remaining patients with poor metabolic control had median 17-OHP levels above 104 ng/mL, 82 ng/mL, 14 ng/mL, and 4 ng/mL, for baseline and 1, 2, and 4 hours, respectively. Differences between the poor and well-controlled group were androstenedione levels with respect to upper limit of normal [1.8 (1.5) and 0.5 (1.5) ng/mL, respectively p=0.03], annual change in height SDS [0.7 (0.2) and -0.03 (0.8) SDS, respectively, p=0.001], and daily hydrocortisone doses [7 (6) and 16 (8) mg/m 2 /day, respectively, p=0.02]. Androstenedione and SHBG levels were negatively correlated in the pubertal children (r s =-0.7, p=0.04)., Conclusion: We conclude that: (i) a 4-hour 17-OHP profile is not useful in predicting hyperandrogenemia; (ii) suppressed levels of 17-OHP do not always indicate overtreatment; (iii) reference intervals of 17-OHP for different time periods might be of importance; (iv) low hydrocortisone doses should be avoided; and (v) SHBG could be used in pubertal children as an indicator of hyperandrogenemia.

Objectives: The exact mechanism of partial clinical remission in type 1 diabetes mellitus (T1DM) has not been elucidated yet. The severity of the inflammation at the time of diagnosis may affect the occurrence or duration of this phase. We aimed to investigate the relationship between hematological inflammatory parameters at the time of diagnosis in T1DM and (i) daily insulin requirement during the follow-up and (ii) the presence of partial clinical remission period, which was determined according to insulin dose-adjusted HbA 1c levels., Methods: A single-center retrospective study was conducted, including children who were diagnosed with T1DM, were positive for at least one autoantibody, and were followed up for one year in our clinic between 2010 and 2020., Results: Sixty-eight patients (55.9% female, 64.7% prepubertal) were included in the study, whose mean age was 8.4 ± 4.2 years. A total of 38 patients (55.9%) had partial clinical remission. None of the initial hematological indices were associated with the occurrence of partial remission. Initial neutrophil/lymphocyte ratio (NLR) and derived-NLR (d-NLR) levels were significantly lower (p=0.011 and 0.033, respectively) and lymphocyte/monocyte ratio (LMR) levels were significantly higher (p=0.005) in patients who showed an insulin requirement of <0.5 IU/kg/day at the 3rd month after diagnosis., Conclusions: Initial hematological parameters were not found as a predictor of partial clinical remission period in T1DM in children. However, a lower NLR and d-NLR, or a higher LMR at the time of diagnosis can be used as an indicator of a low daily insulin need at the 3rd month of T1DM., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Background: Various studies, mainly conducted in adults, have examined the hormonal axis in primary empty sella (PES), and reported various forms of pituitary deficiencies. We report our experience with PES in pediatric patients in terms of pituitary function, associated impairments, and responses to treatment., Methods: We reviewed 10,560 cranial and 325 pituitary magnetic resonance imagings (MRIs) performed at our university hospital between January 2010 and December 2020 and identified patients with PES. Patients with additional abnormal MRI findings, a history of cranial surgery or radiotherapy, autoimmunity, long-term use of chemotherapeutic or immunosuppressive agents or incomplete diagnostic evaluation were excluded. Clinical, radiological and laboratory evaluations were recorded., Results: The study included 17 patients [9 girls, 8 boys; median age 12.4 years (7.25, 4.3 - 17)]. The median size of the pituitary was 2 mm (0.7, 1.2 - 3). Based on age-dependent pituitary height measurements, fifteen (88%) patients had pituitary gland hypoplasia. Five patients presented with short stature, two had both pubertal delay and short stature, and one had pubertal delay. Nine patients presented with neurological symptoms such as headaches, tinnitus, tics, and dizziness. Five short patients had growth hormone deficiency. None of the patients had hyper- or hypoprolactinemia, adrenal insufficiency, hypothyroidism, or diabetes insipidus. There was statistically no significant association between the size of the pituitary gland and the severity of hypopituitarism (p = 0.42)., Conclusions: The high incidence of pituitary dysfunctions ascertain that this entity should not be considered a normal variant but, should instead be carefully evaluated with appropriate basal and dynamic hormonal testing.

Background/aim: Established reference values are critical for the interpretation of immunologic assessments. In particular, the proportion and absolute counts of T- and B- cell subpopulations are subject to change with age and ethnicity. We aimed to establish age- specific reference values for lymphocyte subsets using updated immunophenotyping panels., Materials and Methods: We studied a total of 297 healthy Turkish subjects aged 0 to 50 years, stratified into major age brackets in a cluster factor of 10 per age-group. The predetermined age intervals contained randomly allocated participants enrolled over a period of 6 months, who were homogenously distributed by sex. We analyzed a complete blood count test and simultaneously with detailed immunophenotyping enumerated the percent and absolute cell counts of lymphocyte subsets., Results: The percentage and absolute counts of lymphocyte subsets show a marked surge across the age-span. T helper, T cytotoxic, and the natural killer cell numbers were increasing from birth until 6 months, followed by a gradual decrease thereafter. B cell numbers were rising until 2 years, followed by a gradual decrease for the upcoming years, accompanied by a steady expansion of unclass-switched- and class-switched- B cells., Conclusion: We provide updated extensive reference intervals for lymphocyte subpopulations in Turkish people., (This work is licensed under a Creative Commons Attribution 4.0 International License.)