Unicel dxc800

The exposure variable, TPF, was measured by whole body DXA scan using QDR-4500 Hologic Scanner (Bedford, MA, United States). The outcome variable, SUA, was measured by 704 Multichannel Analyzer or Roche Hitachi Model 917 from 1999 to 2001, Beckman Synchron LX20 from 2002 to 2007, Beckman Coulter UniCel^® DxC800 from 2008 to 2016, and Roche Cobas 6000 (c501 module) in 2017 and 2018.
Other variables included age, sex, race, BMI, ratio of family income to poverty, education level, dietary intakes of energy and nutrients (protein, carbohydrate, and fat), prescription medication use, smoking status (whether smoked at least 100 cigarettes in life), heavy alcohol consumption (ever had 4/5 or more drinks every day), hypertension (mean systolic blood pressure ≥130 mmHg, mean diastolic blood pressure ≥80 mmHg, current use of antihypertensive medications, or self-reported physician-diagnosed hypertension) (19 , 20 (link)), diabetes (self-reported physician-diagnosed diabetes or glycohemoglobin (HbA1c) ≥6.5% in those without a self-reported diagnosis) (21 (link)), weak/failing kidneys (self-reported physician-diagnosed weak/failing kidneys or estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m²) (22 (link)), vigorous work activity and laboratory variables (blood urea nitrogen, cholesterol, triglycerides). These data can be found on the NHANES website.¹

SUA was measured after participants collected blood samples at the mobile examination center, and the samples were cryogenically stored until transported to the collaborating laboratory for analysis. Standardized trained technicians tested SUA concentrations using the Beckman Coulter UniCel® DxC800 (2011-2016) and the Roche Cobas 6000 (2017-2018) [23 ]. Hyperuricemia was initially identified as SUA levels exceeding 7.0 mg/dL in men and 6.0 mg/dL in women [24 (link)]. However, due to the ongoing debate regarding the appropriate cutoff value for elevated SUA levels, we performed a sensitivity analysis employing a cutoff value of SUA ≥6.8 mg/dL. This particular value was chosen as it aligns with the solubility of uric acid under normal physiological pH and temperature conditions [25 (link)].

The exposure variable, VFA, was measured by a dual-energy X-ray absorptiometry (DXA) scan of the entire body using a QDR-4500 Hologic Scanner (Bedford, MA, USA). The serum uric acid (SUA) concentration was detected on a Beckman Coulter UniCel^® DxC800 from 2008–2016 and a Roche Cobas 6000(c501 module) in 2017 and 2018. The HUA was defined by the cut-off values of 7.0 mg/dL for men and 6.0 mg/dL for women [17 (link)].