Subclinical Hypothyroidism in PCOS: Impact on Presentation, Insulin Resistance, and Cardiovascular Risk

Abstract

Aim of Study. To assess status of thyroid function and thyroid disorders particularly subclinical hypothyroidism (SCH) in subjects with polycystic ovarian syndrome (PCOS) and impact of SCH on various clinical and biochemical parameters and cardiovascular risk in PCOS. Methods. Hundred females diagnosed with PCOS as per Rotterdam criteria and 100 normal controls were recruited and were subjected to elaborate anthropometric, clinical, and biochemical assessment. Results. Notable findings included significantly higher frequency of subjects with subclinical hypothyroidism (p = 0.0002), autoimmune thyroiditis (p < 0.001), and goitre (p = 0.02) in polycystic ovarian syndrome subjects compared to control subjects. Further SCH PCOS subjects were found to harbor significantly higher HOMA-IR (p < 0.05) and frequency of subjects with dyslipidemia (p < 0.05) compared to both euthyroid PCOS and euthyroid control subjects. Though frequency of subjects with cardiovascular risk factors was higher in SCH PCOS group than euthyroid PCOS group, it failed to reach statistical significance. Conclusion. We concluded that PCOS is associated with high incidence of SCH and AIT compared to normal population and SCH poses increased risk of cardiovascular disorder in PCOS.

Subclinical Hypothyroidism Impact on the Characteristics of Patients with Polycystic Ovary Syndrome. A Meta-Analysis of Observational Studies

“…The TG levels were significantly higher in SCH-PCOS patients than in euthyroid PCOS patients; previously higher levels of TG were reported in PCOS patients as a whole group [44]. In non-PCOS patients with SCH, TG levels were also found to be higher or not different from those found in healthy controls [10,44,46]. Thyroid hormones may also modulate the carbohydrate metabolism and a possible association between TSH and fasting glucose levels was previously reported [10].…”

“…In non-PCOS patients with SCH, TG levels were also found to be higher or not different from those found in healthy controls [10,44,46]. Thyroid hormones may also modulate the carbohydrate metabolism and a possible association between TSH and fasting glucose levels was previously reported [10]. It was also reported that metformin usage results in slight reduction of TSH levels [47].…”

“…However, the higher levels of TC in SCH-PCOS patients suggest that hypothyroidism may increase intestinal cholesterol absorption, overweighing the effects of decreased hepatic cholesterol synthesis [12,15]. Increased TC level in non-PCOS women with SCH was already demonstrated in most, but not in all, studies [10,42]. Equally higher levels of TC were reported in PCOS patients with TSH either >2.5 or <2.5 [40], but a positive correlation between TSH and TC levels was reported even in euthyroid non-PCOS subjects [43].…”

“…In 2 of the included studies [7,21] SCH-PCOS patients showed significantly higher fasting insulin levels. It was previously shown that patients with SCH, either with or without PCOS, may present decreased insulin sensitivity in adipose and muscle tissues and higher levels of fasting insulin [4,10,23]. Some data have suggested that a decreased blood flow in peripheral tissues is the pathogenic mechanism behind increased insulin levels in women with hypothyroidism.…”

“…High levels of T, fT, LH, PRL, fasting and postprandial insulin, and glycated hemoglobin (HbA1C), increased homeostasis model assessment of insulin resistance index (HOMA-IR), and decreased levels of SHBG may be present in SCH [5,9,10]. Furthermore, SCH seems to be an independent risk factor for infarction and it is more frequent in women with metabolic syndrome [9,11,12].…”