Thyroid Function, Inflammation, and HDL-Cholesterol in Women with Acne: A Real-World Cross-Sectional Study Integrating Biochemistry and Thyroid Ultrasound

Background: Acne in adult women is increasingly recognized as a condition with systemic endocrine–metabolic correlates. Evidence linking acne to thyroid-related abnormalities and cardiometabolic risk markers remains mixed, and integrated real-world evaluations combining thyroid biochemistry, ultrasound metrics, inflammatory indices, and lipid profile are limited. Methods: We performed a cross-sectional observational analysis of 80 women with acne who underwent routine laboratory testing and thyroid ultrasound assessment. Thyroid status was defined using TSH (reference 0.4–4.5 mIU/L) and free T4 (0.8–1.8 ng/dL), with an additional TSH-only sensitivity definition (high TSH >4.5 mIU/L). Low HDL-cholesterol (HDL-C) was defined as 4.5 mIU/L) was strongly associated with low HDL-C (OR 13.13, 95% CI 1.48–116.04; p = 0.020). In a minimal adjusted model including NLR, high TSH remained associated with low HDL-C (adjusted OR 12.93, 95% CI 1.44–115.70; p = 0.022). HDL-C showed an inverse association with NLR (ρ = −0.28; p = 0.023). Endocrine profiling suggested a positive association between ACTH and log(TSH) (ρ = 0.62; p = 0.004), although this did not remain significant after FDR correction. Thyroid ultrasound metrics showed limited correspondence with thyroid biochemistry. Conclusions: In women with acne, elevated TSH is associated with substantially higher odds of low HDL-C, independent of inflammatory burden as proxied by NLR, while thyroid ultrasound morphology contributes limited functional information. These findings support integrated thyroid–metabolic assessment in adult female acne and motivate prospective studies incorporating acne severity measures and standardized testing to clarify clinical implications.