Reference Intervals for Whole-Blood Viscosity Measured Using the Fully Automated Scanning Capillary Tube Viscometer RHEOVIS 200 in Korean Adults

Accurate interpretation of whole-blood viscosity (WBV) requires population-specific reference intervals (RIs), as WBV is influenced by sex, age, and Hct. This study is the first to establish RIs for WBV using a fully automated scanning capillary tube viscometer, RHEOVIS 200 (Biorheologics, Jeonju, Republic of Korea), in Korean adults. WBV was measured in 438 adults at shear rates of 1 s⁻¹ (diastolic WBV) and 300 s⁻¹ (systolic WBV). RIs were determined using the non-parametric method according to CLSI guideline EP28-A3c, and median WBV values were compared by sex and age. At 1 s⁻¹, the RIs were 20.83-38.50 millipascal-second (mPa·s) in all adults, 25.97-39.26 mPa·s in men, and 20.14-35.08 mPa·s in women. At 300 s⁻¹, these were 3.74-5.50 mPa·s in all adults, 4.16-5.60 mPa·s in men, and 3.64-5.05 mPa·s in women. The median WBV was significantly higher in men than in women (P <0.01) and lower in the 20-30-yr group than in other groups (P ≤ 0.03). Sex-specific RIs are required for accurate WBV interpretation in Korean adults, and age-specific RIs require further validation. For WBV measurements using RHEOVIS 200, clinical laboratories should establish and continually verify their own RIs.