The platelet to high-density lipoprotein cholesterol ratio is associated with thyroid hormone abnormalities based on NHANES 2007 to 2012 data.

Thyroid hormone abnormalities are closely associated with metabolic and cardiovascular diseases, yet easily accessible predictors remain limited. This study aimed to investigate the association between the platelet/high-density lipoprotein cholesterol ratio (PHR) and thyroid hormone levels, including thyroid dysfunction. Data from the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2012 were analyzed. Weighted multiple linear and logistic regression models were used to assess the relationship between PHR and thyroid hormone levels, as well as the prevalence of thyroid dysfunction. Subgroup analyses, smoothing curve fitting, and threshold effect analyses were also conducted to further explore potential associations. A total of 8440 participants were included, with a mean age of 47.83 ± 18.48 years and a mean platelet/high-density lipoprotein cholesterol ratio (PHR) of 20.64 ± 8.43. Significant differences in thyroid hormone levels were observed across PHR quartiles, with higher PHR quartiles associated with elevated FT3, TT4, and hypothyroidism prevalence, and lower FT4/FT3 and FT4/TT4 ratios.In unadjusted models, PHR was positively correlated with FT3 (β = 0.007, P < 0.001), TT4 (β = 0.017, P < 0.001), and hypothyroidism (OR = 1.024, P = 0.012), and negatively correlated with FT4/FT3 and FT4/TT4 ratios. After adjusting for potential confounders, these associations remained significant. The odds of hypothyroidism were higher in Q2 and Q4 compared to Q1.Nonlinear associations were observed in the threshold effect analysis, with inflection points for FT3 and TT4 at 10.050 and 24.706, respectively. Below these points, PHR showed a negative association with FT3 and a positive association with TT4, while the associations plateaued above the inflection points. PHR, a readily available biomarker, is significantly associated with FT3, TT4, and the prevalence of hypothyroidism. These findings suggest that PHR could serve as a promising marker for predicting thyroid hormone abnormalities, especially in resource-limited settings where routine thyroid screening is not feasible.