Letter: Effect of posture on laboratory values

Increases in serum lipid and lipoprotein levels with movement from the supine to standing position in adult men and women

The effect of movement from the supine to the standing position on the magnitude of change in serum lipid and lipoprotein levels and its impact on the prediction of risk for coronary heart disease was investigated in 23 male and 18 female subjects. The mean age and body weight of the men was 34 years and 93 kg, respectively, while those of women were 36 years and 71 kg. Thirty minutes of standing following thirty minutes in the supine position was associated with hemoconcentration and a significant (P less than 0.05) plasma volume reduction of -13.8% for men and women combined. Posture-related increases in serum lipids and lipoproteins were similar among both men and women and averaged +12% for triglycerides, +9.3% for total cholesterol, +9.0% for low-density lipoprotein + very low-density lipoprotein cholesterol, and +10.4% for high-density lipoprotein cholesterol. Among men, the latter increased from 41.4 to 45.6 mg X dl-1 while among women, the increase was from 58.0 to 64.3 mg X dl-1. The total cholesterol/high-density lipoprotein cholesterol ratio was unaffected by the change in body position, thus strengthening the reliability of this ratio as a coronary heart disease risk measure. Our findings indicate that body position at time of blood withdrawal significantly influences lipid and lipoprotein levels, and, depending on the absolute concentration values of total or high-density lipoprotein cholesterol, can alter the predictive risk for coronary heart disease. Heart disease. Heart disease risk based on the Framingham probability tables and the multiplier for high-density lipoprotein cholesterol is unaffected by the change in body position.