[The significance and characteristics of the LHRH test in diagnosing precocious puberty development in girls: the stimulated LH/FSH quotient differentiates between central precocious puberty and premature thelarche].

LHRH tests (100 micrograms i.v.) were performed in 31 girls with central precocious puberty (PP); the girls were participating in an international multicentre trial for the treatment of PP with the LHRH agonist decapeptyl in microspheres, together with 18 girls with premature thelarche (PT). Assignment to these two groups was made after 6 months to 5 years of clinical follow-up. LH and FSH were determined centrally using a polyclonal RIA. Basal LH and FSH levels and stimulated LH levels were significantly higher in PP patients (p less than 0.001), but the stimulated FSH levels were not significantly different between the two groups. In the PP group, all stimulated LH levels were above the prepubertal range, whereas in the PT patients all stimulated LH levels were within the prepubertal reference limits. In PP and PT patients 52% and 56%, respectively, of the stimulated FSH levels were increased above the range for prepubertal girls. In 55% of the PP patients, stimulated LH levels were also above the reference range for the corresponding Tanner breast stage. In contrast, all stimulated LH levels of the PT group were within the reference limits for their breast stage. For FSH, 45% and 56% of the stimulated levels were above the normal ranges for the corresponding breast stages in the PP and PT groups, respectively. The LH-to-FSH ratio after LHRH stimulation was significantly higher in the PP than in the PT group (p less than 0.001). All but one of these ratios were above 1 in the PP patients and all ratios in the PT patients were below 1.(ABSTRACT TRUNCATED AT 250 WORDS)