A CLINICALLY USEFUL METHOD FOR DETECTING GONADOTROPINS IN CHILDREN - ASSESSMENT OF LUTEINIZING-HORMONE AND FOLLICLE-STIMULATING-HORMONE FROM URINE AS AN ALTERNATIVE TO SERUM BY ULTRASENSITIVE TIME-RESOLVED IMMUNOFLUOROMETRIC ASSAYS

To study the feasibility of noninvasive sampling in pediatric patients , we examined the concentrations of LH and FSH in paired serum and uri ne samples from 65 children (age 0-15 y) with highly sensitive time-re solved immunofluorometric assays. The detection limits of the assays w ere 0.015 IU/L for LH and 0.018 IU/L for FSH. These sensitivity levels allowed quantification of the low prepubertal LH and FSH concentratio ns. The correlation between serum and urine gonadotropin values was ve ry good (r = 0.751,p < 0.001 for FSH; and r = 0.720, p < 0.001 for LH) , and the urine and serum concentrations were very similar. Correction of urinary gonadotropin concentrations for changes in urinary flow by standard methods using density [concentration x (0.02/density - 1)] o r creatinine (concentration/creatinine) did not improve the correlatio n. Therefore, measurement of urinary gonadotropins without correction can simply be used in the pediatric outpatient setting as a noninvasiv e alternative to serum determinations.