Prevalence of Thyroid Incidentalomas in Adults Attending Clinics in Nnamdi Azikiwe University Teaching Hospital, Nnewi for Unrelated Conditions

For Reprint: [email protected] Trop J Med Res, Vol. 24, No. 1, 2025 Prevalence of Thyroid Incidentalomas in Adults Attending Clinics in Nnamdi Azikiwe University Teaching Hospital, Nnewi for Unrelated Conditions Chinedu G. Azubike1, 2, Michael E. Aronu1, Samuel I. Udobi1, Catherine N. Obasikene1, Kelechi U. Okoye2, Kelechi M. Uke2 and Eric O. Umeh1. 1Department of Radiology, Nnamdi Azikiwe, University, Awka, Nigeria. 2Department of Radiology, Nnamdi Azikiwe Teaching Hospital, Nnewi, Nigeria. ABSTRACT Background: Thyroid incidentalomas (TI) are asymptomatic nodules found incidentally during imaging for unrelated conditions. Highfrequency, high-resolution ultrasound has improved thyroid assessment, increasing detection rates up to 67%. While most lesions are benign, some carry a 10–15% malignancy risk depending on the investigative method. Objectives: The purpose of this study is to determine the ultrasound prevalence of TIs among recruited adult subjects in Nnewi. Materials and Methods: This was a crosssectional study of 400 subjects, scanned using a Mindray ultrasound machine with a 5-12MHz linear array transducer in the Department of Radiology, Nnamdi Azikiwe University Teaching (NAUTH), Nnewi. Subjects who are less than 18 years old, or with evidence of current thyroid disease, visible or palpable thyroid mass, or previous history of thyroid disease were excluded. The data obtained from the study were analyzed using the Statistical Package for Social Sciences (SPSS), Version 25.0. Measures of central tendency and dispersion were used to analyse continuous variables, while frequency was used to analyse both nominal categorical variables and binomial nominal categories. Crosstabulations were conducted for the relevant variables. Results: The study population consisted of four hundred adults, comprising 151 (37.75%) males and 249 (62.25%) females. The mean age of the subjects was 41.30±14.62. The prevalence of TIs was 36.5% and was significantly more common in females. Conclusion: Using high-frequency ultrasound has led to increased detection of incidental thyroid nodules during neck imaging. The prevalence of incidentalomas in this study was higher than values from older studies. Keywords: Prevalence, Thyroid incidentaloma, Thyroid nodules, Ultrasonography. OPEN ACCESS *Correspondence Michael E. Aronu Department of Radiology, Nnamdi Azikiwe, University, Awka, Nigeria/ Nnamdi Azikiwe Teaching Hospital, Nnewi, Nigeria. Email: [email protected] Tel: +2348068457890. Article Metrics Submitted: 25 July 2024 Accepted: 19 Sept 2025 Published: July-Dec 2025 Citation: Chinedu GA, Aronu ME, Udobi SI, Obasikene CN, Okoye KU, Uke KM, et al. Prevalence of Thyroid Incidentalomas in Adults Attending Clinics in Nnamdi Azikiwe University Teaching Hospital, Nnewi for Unrelated Conditions. Trop J Med Res. 2025:24(1);77-82. DOI: 10.5281/zenodo.17385468. Journal Metrics ISSN: p1115-0521, e3027-2890 Website: www.orientjom.org.ng E-mail: info. [email protected] Publisher: cPrint, Nig. Ltd Email:[email protected] Access Code www.tjmr.org.ng Original Article www.tjmr.org.ng 78 For Reprint: [email protected] Trop J Med Res, Vol. 24, No. 1, 2025 Prevalence of Thyroid Incidentalomas in Adults Chinedu GA et al., INTRODUCTION here is a general increase in the prevalence of thyroid incidentalomas due mostly to better technological advancements in high-frequency and high-resolution ultrasound probes in current use. This has led to a rise in many subcentimetre nodules previously undetectable by both ultrasound and clinical palpation.[1] A thyroid incidentaloma (TI) is defined as an unexpected, asymptomatic thyroid lesion fortuitously discovered during investigation of an unrelated condition.[2-6] They represent a clinical challenge; thus, there is a great need to assess the risk of each nodule for cancer. [2-3] Thyroid cancer is uncommon, accounting for about 1,000 new cases and 300 deaths in England and Wales per annum, while in the United States, there are about 12,000 new thyroid cancers and approximately 1000 deaths per annum.[2-3] The management of an incidental thyroid nodule is controversial. There is a dilemma between the need to avoid burdening the health care system with overinvestigation of benign nodules and the need to prevent the adverse effects that follow a delayed cancer diagnosis. [3-4] Ultrasonography is the most accurate and costeffective method of imaging the thyroid.[3-4]. Ultrasound (US) is also non-invasive, readily available, and non-ionising; thus, it is an ideal screening tool for nodular and diffuse thyroid diseases.[5-6] High-resolution US, with its improved sensitivity, has increased the frequency of detection of incidental thyroid nodules.[3,7] The risk of malignancy among detected TIs has been reported in some studies to be as high as 12.9%.[8] US-guided fine-needle aspiration cytology (FNAC) is the test of choice for determining the nature of nodules. It is imperative to reduce the number of unnecessary FNACs while identifying clinically significant malignant nodules. In a study conducted in Ibadan, Nigeria, in 2011 by Olusola-Bello et al2 the US prevalence of TIs was reported as 22.4%. Another study conducted in Cameroon in 2017 noted that TIs were very frequent, with a prevalence of 28.3%.[8] The prevalence of TIs is generally higher in females, with increasing age and in iodine deficiency[3,9] Thyroid incidentalomas are a global concern despite the dearth of research on the subject in Nigeria. With increasing detection due to more sensitive imaging, TIs often pose a clinical dilemma when found. To this end, many professional organizations have proposed ways to identify nodules that require active surveillance. For instance, in 2012, the American College of Radiology (ACR) convened committees to investigate incidental thyroid nodules. By 2015, these committees published a white paper that presented an approach to TIs. Two years later (2017), ACR TIRADS (thyroid imaging, reporting and data system) was created.[10,11] TIs carry a risk of malignancy. This underscores the importance of early detection and acquisition of data that reflects prevalent local ultrasound characteristics. Such data can also be considered regionally to nationally representative. In Nigeria and Sub-Saharan Africa, there is a paucity of data on this important matter, hence the need for this study. The purpose of this study is to determine the ultrasound prevalence of TIs among recruited adult subjects in NAUTH, Nnewi. MATERIALS AND METHODS This was a cross-sectional study done over six months (January 2023 - June 2023) on adult subjects recruited from Nnamdi Azikiwe University Teaching Hospital (NAUTH) in the Nnewi North Local Government Area of Anambra State, Nigeria, according to the 2006 Nigerian census12, Nnewi North has an estimated population of 155,443. The sample size for this study was calculated using the formula N = Z2 pq/e2 13. Using a prevalence of TIs estimated to be 33.4% by Tadesse et al14. When calculated and a 10% attrition rate added, this was rounded to 400 subjects recruited for the study. The inclusion criteria for this study are consenting adult subjects who are 18 years of age or older, who are T 79 Prevalence of Thyroid Incidentalomas in Adults Chinedu GA et al., For Reprint: [email protected] Trop J Med Res, Vol. 24, No. 1, 2025 either volunteers or patients referred for imaging to the Department of Radiology of NAUTH for reasons other than thyroid disease. The exclusion criteria include subjects less than 18 years old, evidence of current thyroid disease, a visible or palpable thyroid mass, previous history of thyroid disease, previous history of thyroid surgery or radioiodine therapy, family history of thyroid disease in a first-degree relative, pregnant women, and those who do not give consent for the study. Subjects’ socio-demographic information (like age, sex) as well as clinical information were collected and documented. The radiologist scanning the patient was accompanied by another radiologist, and the two were blinded from the patient’s information. The two were involved in making decisions on the scan findings so as to reduce intra-observer bias. Sampling was consecutive until the required number was obtained. The study was approved by the NAUTH Ethical Committee. The data collected was treated with confidentiality. The research was solely sponsored by the authors. There was no conflict of interest or direct benefit to the subjects. Non-consenting subjects were not discriminated against. The subjects were scanned using a Mindray ultrasound machine (model: DC-32 SN: 9Q98000221; manufactured 18-08-2019) with a 512MHz linear array transducer. Both lobes and the isthmus of the thyroid gland were scanned in the axial and longitudinal planes. Number, size and other ultrasound characteristics of thyroid nodules were recorded in the study data sheet. The ultrasound scan was free for the participants, with departmental approval. The data obtained from the study were analysed using the Statistical Package for Social Sciences (SPSS), Version 25.0 (IBM Corp., Released 2017, IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp.). Measures of central tendencies (mean and mode) and dispersions (range and standard deviation), were used to analyze continuous variables (like age of the subjects); while frequency was used to analyze nominal categorical variables (like sex), and binomial nominal categories (like presence/absence of nodules). Crosstabulations were conducted for the relevant variables. Results were displayed in tables and charts. RESULTS A total of 400 consenting adults were involved in this study. This comprised 151 (37.75%) males and 249 (62.25%) females. The mean age of the study subjects was 41.30±14.62 years, with a range of 1887 years. The highest proportion of the respondents, 141 (35.25%), were within 29-39 years of age, while the least frequent were those above 84 years of age (1%). (Table 1) Table 1: Age and sex distribution of subjects Age group (years) Sex Total freq. (%) Female Male 18-28 61 (24.5) 15 (9.9) 76 (19.0) 29-39 98 (39.4) 43 (28.5) 141 (35.2) 40-50 46 (18.5) 45 (29.8) 91 (22.7) 51-61 18 (7.2) 25 (16.6) 43 (10.7) 62-72 20 (8.0) 13 (8.6) 33 (8.3) 73-83 6 (2.4) 6 (4.0) 12 (3.0) 84 and above 0 4 (2.6) 4 (1.0) Total 249 (100.0) 151 (100.0) 400 (100.0) Of the 400 subjects, 254 (63.5%) had normal appearing thyroid glands, while 146 (36.5%) had incidental thyroid nodules; the prevalence of TIs was thus 36.5%. Among the ones with thyroid incidentalomas, 73.97% of subjects had a single nodule, followed by 17.80% of subjects with 2 incidental nodules, and 16.43% of subjects had nodules in multiple locations/lobes. The least common location was the isthmus. Subjects with nodules in the right or left lobe only are equal 56 (38.36%). (Table 2) 80 For Reprint: [email protected] Trop J Med Res, Vol. 24, No. 1, 2025 Prevalence of Thyroid Incidentalomas in Adults Chinedu GA et al., Table 2: Distribution of TIs among the study participants Variable Frequency Percentage (%) Thyroid nodule No 254 63.50 Yes 146 36.50 Number of nodules per subject One 108 73.97 Two 26 17.80 Three 12 8.21 Location (n=146) Isthmus only 10 6.85 Left only 56 38.36 Multiple lobes 24 16.43 Right only 56 38.36 The prevalence of TIs is 36.5%, with 29% being female subjects and 7.5% being male subjects. Female subjects had more incidental nodules with TIs noted in 116 out of 249 female subjects recruited, while 30 out of 151 male subjects had Tis. (Table 3) Table 3: Prevalence of thyroid incidentalomas among recruited subjects. Gender Prevalence of TI in either lobe (%) Total (%) No incidentaloma Incidentaloma Females 133 (33.25) 116 (29) 249 (62.25) Males 121 (30.25) 30 (7.5) 151 (37.75) Total 254 (63.5) 146 (36.5) 400 (100.0) The right lobe was the commonest location for TIs in males (53.3%), while for female subjects, the left lobe was the commonest site (41.4%). The isthmus was the least common site for incidental thyroid nodules in both males and females. (Table 4) Table 4: Prevalence of incidentalomas in both lobes of the thyroid gland among recruited subjects. Location of incidentaloma Gender (n=146) Total (%) Females Males Isthmus only 8 (6.9) 2 (6.7) 10 (6.8) Left only 48 (41.4) 8 (26.7) 56 (38.4) Multiple lobes 20 (17.2) 4 (13.3) 24 (16.4) Right only 40 (34.5) 16 (53.3) 56 (38.4) Total 116 (100.0) 30 (100.0) 146 (100.0) DISCUSSION Thyroid incidentalomas are unexpected, asymptomatic lesions inadvertently discovered during imaging investigation of the neck for an unrelated condition. When found, they are a clinical dilemma because they carry a risk of malignancy. Thus, early detection and acquisition of data that reflects prevalent local ultrasound characteristics are important. The overall prevalence of TI in this study was 36.5%. This value is higher than the values from previous studies. Olusola-Bello et al2 studied the prevalence of TIs in Ibadan, Nigeria, in 2011 and recorded a significantly lower value of 22.4%. Similarly, a lower prevalence of 19.6% was noted in the valley of Mexico in 2011.[15]. Some other studies record similarly higher values, like 33.4% recorded by Tadesse et al.[14] in the Northwest of Ethiopia in 2019 and 28.3% by Moifo et a[3] in 2015 in sub-Saharan Africa. This difference in ultrasound prevalence depends on various factors like the population studied, the technology used (ultrasound probe frequency), the mean age and sex of the subjects sampled and radiation exposure, particularly in infancy or childhood. Certain modifiable factors may also influence prevalence, and they include the iodine status of the population, smoking, anthropometric indices, diabetes mellitus, previous history of thyroid disease, as well as a positive family history of thyroid disease.[3,7,17-19] The findings in this study show that TIs increase with age. This might be explained as normal physiologic age-related changes in the Thyroid gland.[20] The later studies record higher prevalence, likely due to better ultrasound technology (higher-frequency transducers), especially since Iodine deficiency is barely a problem in modern times.[14] TI was also much more common in females than in males, and findings in other studies corroborate this. In some of these studies, the female preponderance was statistically insignificant.[21] The study by Olusola-Bello et al.[2]. In Ibadan, Nigeria, the female preponderance was statistically insignificant (p=0.09), but statistically significantly higher female prevalence has also been reported.[3,14] The female-to-male ratio in this study is almost 4:1. There is little variation in the generally observed pattern/characteristics of thyroid incidentalomas 81 Prevalence of Thyroid Incidentalomas in Adults Chinedu GA et al., For Reprint: [email protected] Trop J Med Res, Vol. 24, No. 1, 2025 among researchers. The incidental nodules were predominantly single in this study (73.97%), and this is in agreement with several other studies.[2,14,17] Regarding size, most of the detected incidental thyroid nodules in this study were <1cm. Other studies also report most TIs as subcentimetre in size.[2-3,14,17,22] This is why they often escape clinical detection by palpation or self-observation by the patient! This was a hospital-based study and therefore, may not reflect the true prevalence in the community. The other limitation is the operator dependence of ultrasound even though will be reduced by the fact that data was collected by one the researchers under the supervision of a senior and experienced consultant radiologist. The strength of the study comes from the availability of ultrasound with advanced features and the high sensitivity and specificity of ultrasound as an imaging modality in thyroid studies. CONCLUSION The advent and widespread use of high-frequency and high-resolution ultrasound has led to an increase in the detection of incidental thyroid nodules during imaging of the neck. For instance, the prevalence of incidentalomas in the index study is 36.5%. Since most of them are small, nonpalpable and clinically innocuous, they pose a clinical problem especially when malignant. The limitation of the study is that it is a hospitalbased study, and the findings from it may not be easily generalisable to the general population. Many clinical and biochemical factors affect the prevalence of TIs that were not taken up by this study because of the economic base of the researchers at the time. We recommend a more detailed study that will take care of these in a wide population-based study because of the importance of these findings, to correctly manage thyroid incidentaloma among our people. Acknowledgements: Not applicable Authors’ contributions: Conception and design of the study – GCA, MEA, EOU. Data collection, generation of sonographic images/image editing – GCA, CNO, KUO, MUO. Data analysis and interpretation – SIU, MEA Drafting of the workGCA, CNO, KUO, KMU. Reviewing of the work for important intellectual content: MEA, SIU, EOU. Final proof reading and approval of the version to be used – All authors. Data availability: The datasets used and/or analyzed during the current study are available upon reasonable request from the corresponding author. Funding: No funding sources. 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