Thyroid Sensitivity and Metabolic Syndrome
The Association between Thyroid Hormone Sensitivity and Metabolic Syndrome in a Chinese Euthyroid Population: The Pinggu Metabolic Disease Study
Introduction
This study is centered on examining the potential relationship between sensitivity to thyroid hormones and metabolic syndrome (MetS), alongside its associated elements, in a Chinese population that is euthyroid, i.e., individuals having normal thyroid function. Metabolic syndrome refers to a cluster of conditions that occur together, increasing your risk of heart disease, stroke, and type 2 diabetes. These conditions may include increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels. The objective was to determine whether the sensitivity of the body's response to thyroid hormones might be a contributing factor in MetS and its components.
Methods
The team of researchers investigated a sample group of 3,573 participants hailing from the Pinggu Metabolic Disease Study. They recorded and examined multiple variables for each participant, which included serum-free triiodothyronine (FT3), free thyroxine (FT4), thyrotropin (TSH), total adipose tissue (TAT), visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) in the abdominal area, and the lumbar skeletal muscle area (SMA). Central thyroid hormone resistance was quantified using the Thyroid Feedback Quantile-based Index (TFQI) and the Chinese-referenced Parametric TFQI (PTFQI), Thyrotroph T4 Resistance Index (TT4RI), and the TSH Index (TSHI). Meanwhile, peripheral thyroid hormone resistance was assessed using the FT3/FT4 ratio.
Results
Results demonstrate significant associations between thyroid hormone sensitivity and MetS. Higher values of TSHI, TT4RI, TFQI, and PTFQI, and lower values of FT3/FT4 ratio were associated with a greater likelihood of MetS. In more detail, increased levels of TFQI and PTFQI were found to be linked with abdominal obesity, hypertriglyceridemia (excess levels of triglycerides in the blood), and hypertension (high blood pressure). Meanwhile, elevated levels of TSHI and TT4RI were associated with hypertriglyceridemia, abdominal obesity, and low levels of high-density lipoprotein cholesterol (HDL-C), often termed "good cholesterol". Furthermore, reduced levels of FT3/FT4 ratio were correlated with hyperglycemia (high blood sugar), hypertension, and hypertriglyceridemia. Observably, TSHI, TFQI, and PTFQI levels were negatively related to SMA, implying lower muscle mass, and positively related to VAT, SAT, and TAT, indicating higher fat mass (all p < 0.05).
Conclusions
The findings of the study suggest a significant association between reduced sensitivity to thyroid hormones and metabolic syndrome, along with its various components. This implies that thyroid hormone sensitivity could potentially affect the distribution of adipose tissue and muscle in the body. These findings underscore the possible role of thyroid hormone sensitivity in the onset and development of metabolic syndrome and the conditions associated with it. Future research may help to establish whether adjusting thyroid hormone levels could be an effective approach in managing metabolic syndrome.
Lv F, Cai X, Li Y, et al. Sensitivity to thyroid hormone and risk of components of metabolic syndrome in a Chinese euthyroid population. Journal of Diabetes. 2023 Jul. DOI: 10.1111/1753-0407.13441. PMID: 37429739.
I imagine that physicians may roll their eyes with the idea that thyroid resistance exists. . . how is it that we can agree that insulin resistance is a prominent issue but when it comes to other hormones we can't fathom the thought. Jason & Rita...aka Dr. De Leon and Dr. Gillespie.
