Effect of IGF-1 on Thyroid Nodules and its Relation to Insulin Resistance
Authors: Abdelraouf Reham Mahmoud , Abelsalam Mona Mohamed , Bekhet Meram Mohamed , Ahmed Nesma Hussien 
Published: November 2024

Abstract

Background
The insulin/IGF-1 signaling pathway modulates the regulation of thyroid gene expression and it is an important factor in the proliferation and differentiation of thyroid cells. Numerous growth factors are identified in thyroid tissue: like epidermal growth factor (EGF), transforming growth factor- alpha (TGF-alpha), IGF receptor (IGF-R), insulin-like growth factor-1 (IGF-1), IGF1-receptor (IGF-R) and IGF binding proteins (IGFBPs) Overexpression of these growth factors and/or their receptors may play a role in the growth of the thyroid nodules. in addition to TSH, insulin is also a thyroid growth factor that stimulates the growth of thyroid cells.

Aim of Work
The aim of this study is to investigate the possible association between IGF-1 and thyroid nodules by determining the effect of serum IGF-1 on thyroid nodules and its u/s findings and to investigate IGF-1 relation with insulin resistance (IR) and whether IR also plays a role in the thyroid nodular formation and its ultrasonography(u/s) findings.

Patients and Methods
A total of 80 medically free euthyroid patients with thyroid nodules detected by clinical examination (palpation) and radiologically by neck u/s screening were selected from out patient endocrine clinic at Ain Shams University hospitals. for all participants the following was done: Glycemic profile (fasting plasma glucose (mg/dl), 2hours post prandial plasma glucose (mg/dl) and HBA1C(%)), Lipid profile (total cholesterol (mg/dl), LDL (mg/dl), HDL (mg/dl), triglycerides (mg/dl)),The thyroid function evaluation (free tetra iodothyronine (FT4)(ng/dl), (free tri iodothyronine (FT3)(pg./ml) and serum thyroid stimulating hormone (TSH)(uIU/ml), IGF-1 determined by enzyme linked immunosorbent assay (ELISA), Fasting serum insulin determined by (ELISA), HOMA-IR was determined for all patients as a quantitative method for insulin resistance. Neck u/s was done for all patients with TIRADS score of the nodule.

Results
The study conducted on 80 medically free euthyroid patients with thyroid nodules and revealed that IGF-1 was high in patients with thyroid nodules. but there was no statistical association with nodular number, size or volume, p value (0.184,0.75,0.25), respectively. there was a statistically significant association between IGF-1 and TIRADS score of the nodule, p value = (0.039). There was an association between HOMA-IR, volume and size of the nodules, p value (0.023,0.013), respectively. but no statistical significance with number of the nodules, p value (0.279). by logistic regression analysis HOMA-IR can’t be used as a predictor of nodular size and volume p value (0.384). there was a statistical significance between presence of metabolic syndrome and number of nodules, p value (0.048). also, there was no association between serum IGF-1 and HOMA-IR, p value (0.077).

Conclusion
IGF complex is involved in thyroid development and seems to play an important role in thyroid nodules formation. There is an association between IGF-1 and thyroid nodules but it may exert its effect through autocrine and paracrine pathways; therefore, the use of circulating IGF-1 levels in predicting and diagnosing thyroid nodules is not advisable. There is an association between metabolic syndrome and number of thyroid nodules, also a significant relationship was found between nodule formation and insulin resistance. Presence of Insulin resistance leads to higher nodular volume and size in non-diabetic euthyroid patients but HOMA-IR can’t be used as a predictor of nodular size or volume. However, these data must be confirmed by further studies in the future.