Factors Associated with the Occurrence of Thyroid Nodules in Severely Obese Patients: A Case-Control Study

The impact of anthropometric parameters and sonographic characteristics on the choice of biopsy method for thyroid nodules: Fine-needle aspiration versus non-aspiration biopsy

Objective

The accurate diagnosis of thyroid nodules is crucial for effective management and the detection of malignancy. Fine-needle aspiration biopsy (FNAB) and fine-needle non-aspiration biopsy (FNNAB) are widely used techniques for evaluating thyroid nodules. In this study, we aimed to investigate the impact of anthropometric parameters and sonographic characteristics on the choice between FNAB and FNNAB in terms of diagnostic yield.

Material and Methods

This retrospective and cross-sectional analysis involved 188 cases with a total of 225 thyroid nodules. Each nodule initially underwent either FNAB or FNNAB and if the initial biopsy did not yield a diagnostic result, the nodule was re-biopsied using the alternate technique. Ultrasound was used to evaluate the nodules, with a focus on echogenicity, calcifications, size, vascularity, and the presence of a halo sign. Both FNAB and FNNAB were performed using a 25-gauge needle, with the only difference being the application of suction.

Results

FNAB demonstrated a higher diagnostic rate for nodules with a taller-than-wide shape (anteroposteriorto-transverse ratio ≥1), nodules sized 10-40 mm, nodules with volumes <0.5 cc, and hypoechoic nodules (P < 0.001 for all). FNAB also outperformed FNNAB in the assessment of the right-sided, inferior, and posterior nodules (P < 0.001), nodules with and without calcification (P = 0.041 and P = 0.020, respectively), and nodules with type 1 and type 2 vascularity patterns (P = 0.006 and P = 0.017, respectively). FNAB was effective in obese individuals (Body mass index ≥40 kg/m2), males with a waist circumference of <94 cm, females with a waist circumference of ≥80 cm, and females with a neck circumference of ≥34 cm (P = 0.011, P = 0.044, P = 0.029, and P = 0.008, respectively).

Conclusion

Anthropometric parameters and sonographic characteristics influenced the diagnostic yield of FNAB and FNNAB, with FNAB generally demonstrating superior results. Given the importance of obtaining an accurate diagnostic result from fine-needle biopsy, clinicians should consider both the sonographic features of the nodule and the anthropometric measurements of the patient when selecting a biopsy technique.

Establishment and validation of a multivariate logistic model for risk factors of thyroid nodules using lasso regression screening

Objective

This study aims to analyze the association between the occurrence of thyroid nodules and various factors and to establish a risk factor model for thyroid nodules.

Methods

The study population was divided into two groups: a group with thyroid nodules and a group without thyroid nodules. Regression with the least absolute shrinkage and selection operator (Lasso) was applied to the complete dataset for variable selection. Binary logistic regression was used to analyze the relationship between various influencing factors and the prevalence of thyroid nodules.

Results

Based on the screening results of Lasso regression and the subsequent establishment of the Binary Logistic Regression Model on the training dataset, it was found that advanced age (OR=1.046, 95% CI: 1.033-1.060), females (OR = 1.709, 95% CI: 1.342-2.181), overweight individuals (OR = 1.546, 95% CI: 1.165-2.058), individuals with impaired fasting glucose (OR = 1.590, 95% CI: 1.193-2.122), and those with dyslipidemia (OR = 1.588, 95% CI: 1.197-2.112) were potential risk factors for thyroid nodule disease (p<0.05). The area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the Binary Logistic Regression Model is 0.68 (95% CI: 0.64-0.72).

Conclusions

advanced age, females, overweight individuals, those with impaired fasting glucose, and individuals with dyslipidemia are potential risk factors for thyroid nodule disease.

Thyroid Nodules and Obesity

A widely discussed topic in the pathophysiology of thyroid nodules is the role of obesity, a state that leads to increased systemic inflammatory markers. Leptin plays a vital role in forming thyroid nodules and cancer through several mechanisms. Together with chronic inflammation, there is an augmentation in the secretion of tumor necrosis factor (TNF) and the cytokine interleukin 6 (IL-6), which contributed to cancer development, progression and metastasis. In addition, leptin exerts a modulatory action in the growth, proliferation and invasion of thyroid carcinoma cell lines via activating various signal pathways, such as Janus kinase/signal transducer and activator of transcription, mitogen-activated protein kinase (MAPK) and/or phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt). Through several proposed mechanisms, aberrant endogenous estrogen levels have been suggested to play a vital role in the development of both benign and malignant nodules. Metabolic syndrome triggers the development of thyroid nodules by stimulating thyroid proliferation and angiogenesis due to hyperinsulinemia, hyperglycemia and dyslipidemia. Insulin resistance influences the distribution and structure of the thyroid blood vessels. Insulin growth factor 1 (IGF-1) and insulin affect the regulation of the expression of thyroid genes and the proliferation and differentiation of thyroid cells. TSH can promote the differentiation of pre-adipocytes to mature adipocytes but also, in the presence of insulin, TSH possesses mitogenic properties. This review aims to summarize the underlying mechanisms explaining the role of obesity in the pathophysiology of thyroid nodules and discuss potential clinical implications.

Benign nodules of the thyroid gland and 25-hydroxy-vitamin D levels in euthyroid patients

BACKGROUND

The presence of nodules in the thyroid gland is common in iodine-deficient areas of the world. Recently, vitamin D levels were found to be lower than normal and sometimes deficient in malignant nodules of the thyroid.

OBJECTIVE

Evaluate the relationship between the serum vitamin D levels and benign thyroid nodules in euthyroid patients.

DESIGN

Cross-sectional.

SETTING

Tertiary care center in Turkey.

PATIENTS AND METHODS

Patients referred to the general surgery outpatient clinic and diagnosed with thyroid nodules were the study group. The control group consisted of healthy individuals without thyroid nodules. Age, BMI, thyroid ultrasonography, serum 25-hydroxyvitamin D, free T3, free T4, thyroid stimulating hormone, calcium, magnesium, phosphorous, total protein, albumin, glucose, creatinine levels and glomerular filtration rate (GFR) were compared between groups.

MAIN OUTCOME MEASURE

Serum 25-hydroxy-vitamin D levels and size of the thyroid nodules.

SAMPLE SIZE AND CHARACTERISTICS

Of 849 individuals, 453 were patients with thyroid nodules and 396 were healthy individuals.

RESULTS

The mean serum vitamin D levels of patients with thyroid nodules were significantly lower than controls (P<.001). Serum vitamin D levels along with serum total protein levels and eGFR were independent variables associated with the presence of a thyroid nodule (P<.001, p=.005 and P=.017, respectively).

CONCLUSION

These findings suggest vitamin D deficiency might be one of the pathophysiologic factors in development of thyroid nodules.

LIMITATION

Single-center and possible information bias.

CONFLICTS OF INTEREST

None.

Thyroid Nodules in Severely Obese Patients: Frequency and Risk of Malignancy on Ultrasonography

Background: We aimed to compare the thyroid ultrasonographic findings of severely obese versus nonobese individuals, and the frequency, characteristics, and risk of malignancy in detected nodules.Design: Case-control study including 67 adults with severe obesity (body mass index [BMI] ≥ 35 kg/m²) and 67 nonobese controls (BMI < 30 kg/m²). The participants underwent ultrasound evaluation of the thyroid and cervical subcutaneous tissue. The risk of malignancy in detected nodules was determined using the American Thyroid Association (ATA) 2015 and the Thyroid Imaging Reporting and Data System (TI-RADS) classifications. Fine-needle aspiration biopsy (FNAB) was performed in nodules for which the procedure was recommended according to the ATA-2015 or TI-RADS criteria, and the cytological evaluation followed the Bethesda classification.Results: The mean BMI values in the case and control groups were 47.0 ± 6.1 kg/m² and 22.8 ± 2.7 kg/m², respectively. There were no differences between groups regarding sex, age, total T3, and antiperoxidase (antiTPO) antibody positivity. When compared with controls, severely obese individuals showed a greater frequency of parenchymal hypoechogenicity (p = 0.042), cervical subcutaneous tissue thickness (p < 0.001), overall frequency of thyroid nodules (p = 0.038), and frequency of multiple nodules (p = 0.013). No significant differences were observed in terms of risk of nodular malignancy according to both the ATA-2015 and TI-RADS classifications in severely obese compared with nonobese individuals.Conclusions: Severely obese individuals (versus nonobese controls) presented increased parenchymal hypoechogenicity and frequency of thyroid nodules on ultrasonographic evaluation. However, no significant differences were observed in terms of risk of nodular malignancy between both groups according to the ATA-2015 and TI-RADS criteria. Thus, ultrasonographic thyroid screening of severely obese individuals is not justified.