CRP and myalgic encephalomeyelitis/chronic fatigue syndrome: In multivariate models that adjusted for age, BMI, diabetes, cardiovascular diseases, prevalent fractures, serum albumin, and CRP, which were variables with P < 0.05 in univariate analyses, serum magnesium levels were independently associated with increased CFS scores (β = − 0.126, P = 0.005) (Table 2).