CALCULATED WHOLE BLOOD VISCOSITY IS SPECIFICALLY ASSOCIATED WITH ABDOMINAL OBESITY, BUT NOT WITH OTHER COMPONENTS OF METABOLIC SYNDROME: A CROSS-SECTIONAL STUDY IN A CENTRAL ASIAN ADULT COHORT.

INTRODUCTION: Metabolic syndrome (MetS) is a heterogeneous condition, and its individual components may reflect haemorheological disturbances to differing degrees. Estimated whole blood viscosity (WBV), computed from haematocrit and total protein using the de Simone formulas, is a non-invasive marker of potential microcirculatory disturbance. Existing data on the relationship between WBV and MetS in Central Asian populations remain limited and conflicting. AIM: To evaluate the associations between estimated WBV and abdominal obesity as the leading anthropometric component of MetS, as well as its associations with the remaining components and the composite diagnosis of MetS, in an adult Central Asian population. MATERIAL AND METHODS: This cross-sectional study enrolled 359 adults (18-65 years) from Turkestan, Kazakhstan. WBV was calculated at two shear rates (208 s-1 and 0.5 s-1) using the de Simone formulas. MetS components were defined according to the IDF 2006 criteria. The Mann-Whitney U test and the χ² test (or Fisher's exact test) were used for bivariate comparisons; multivariable logistic regression was performed with WBV quartiles as predictors; models were adjusted for age, sex, ethnicity, smoking and alcohol consumption; BMI was added to all models except the one for abdominal obesity (because of collinearity with waist circumference). RESULTS: Abdominal obesity showed a strong dose-dependent association with WBV: the adjusted odds ratio (aOR) for the highest vs. lowest WBV quartile was 5.03 (95% CI 1.62-15.60; p=0.005) at 208 s-1 and 4.38 (1.45-13.22; p=0.009) at 0.5 s-1. The effect persisted with WBV as a continuous variable (aOR 3.04 per 1 cP at 208 s-1; p<0.001). The remaining components - elevated blood pressure, hypertriglyceridemia, low HDL-C and impaired glucose metabolism - showed no significant association with WBV quartiles after adjustment. The composite MetS was likewise not significantly associated with WBV after adjustment (aOR Q4 vs. Q1=1.20, p=0.52). CONCLUSION: Estimated WBV is specifically associated with abdominal obesity, but not with the metabolic or hypertensive components of MetS after multivariable adjustment. This finding is consistent with the biological role of haemoconcentration and plasma volume as the leading determinants of the de Simone formula parameters. Estimated WBV may represent a marker of anthropometric rather than metabolic disturbance in the Central Asian population and should not be regarded as an independent predictor of composite MetS in such cohorts.