Association between serum estradiol level and appendicular lean mass index in middle-aged postmenopausal women

Table 4 Threshold effect analysis of serum estradiol level on appendicular lean mass index using two-piecewise linear regression model

Appendicular lean mass index	Adjusted β (95%CI), P value
Serum estradiol level
Fitting by standard linear model	0.001 (0.000, 0.002), 0.006
Fitting by two-piecewise linear model
Inflection point	85 (pg/mL)
Serum estradiol level < 85 (pg/mL)	0.004 (0.002, 0.007), < 0.001
Serum estradiol level > 85 (pg/mL)	-0.001 (-0.003, 0.001), 0.280
Log likelihood ratio	0.003

Age, race, educational level, body mass index, ratio of family income to poverty, moderate activities, total protein, blood urea nitrogen, serum uric acid, and serum calcium were adjusted.