Age- and sex-specific reference values for plasma lipids and lipoproteins in thai adults: a national health examination survey analysis.

BACKGROUND: Age-, sex-, and country-specific reference values for lipoprotein levels are essential for identifying lipoprotein disorders, such as familial hypercholesterolemia (FH). However, the Thai-specific data are limited. This study aimed to establish age-and sex-specific reference percentiles for lipid and lipoprotein levels in Thai adults. METHODS: This study analyzed plasma lipid and lipoprotein levels from the 6th National Health Examination Survey (NHES-VI) conducted in Thailand. Data from Thai adults without cardiovascular disease or lipid-lowering medication were examined to determine age- and sex-specific percentiles. Participants were grouped into 5-year age intervals for both sexes to assess trends across the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles of lipid measurements. The weighting was applied to account for the complex survey design and ensure representativeness of the national population. The Kruskal-Wallis test was used to examine statistically significant differences in lipid levels between age groups within sex. A P-value < 0.05 was considered significant. RESULTS: 17,018 participants (7,244 men and 9,774 women) aged ≥ 20 years were included. Both total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels increased with age in both sexes. The highest median LDL-C levels were found in men aged 45-49 (129 mg/dL) and women aged 55-59 (137 mg/dL). The median and 95th percentile values of LDL-C across different age groups were 126 and 194 mg/dL in men, and 131 and 198 mg/dL in women, respectively. High-density lipoprotein cholesterol (HDL-C) levels were higher in women than in men across all age categories, whereas triglyceride levels were higher in men than in women in all age categories below 70 years old. These findings highlight important age-and sex-related differences that may inform clinical cut-offs for lipoprotein disorders in Thailand. CONCLUSIONS: This study establishes the first comprehensive, population-based reference values for lipids in the Thai adult population. Our data reveal notably high LDL-C levels compared with other populations, suggesting that the current universal diagnostic thresholds for lipid disorders may need re-evaluation in the Thai context. These findings provide a crucial evidence base for updating national clinical guidelines and public health strategies.