Table 4.

Multivariable quantile regression results for reference interval limits. Lower and upper bound are estimated as 0.025 and 0.9 quantile from the regression. Standard errors are estimated using the NY bootstrap strategy

Bound	Covariates	Coefficients	Standard Error	P-value
Lower	M probe	-0.834	0.135	< 0.001
	Age	0.041	0.017	0.017
Upper	M probe	-1.296	0.271	< 0.001
	Age	0.127	0.043	0.003
Median	M probe	-0.807	0.119	< 0.001
	Age	0.030	0.015	0.046