The differentiation between premature thelarche and pubertas praecox on the basis of clinical, hormonal and radiological findings

In a retrospective study of 39 girls (aged 10 months to 7 10/12 years) with premature breast development criteria for distinguishing between premature thelarche and precocious puberty were analysed. Serum estradiol levels and bone age were determined and a test with luteinizing hormone-releasing hormone (LHRH) performed (inclusion criteria). On the basis of the LHRH test and bone age, premature thelarche was diagnosed in 29 patients and precocious puberty in ten: while those with premature thelarche had a follicle-stimulating hormone (FSH) pattern of rise, in those with precocious puberty the rise in gonadotropin was of the LH type. The LH/FSH ratio 30 min after stimulation was < 1 (median 0.15 [0.03-0.34] in patients with premature thelarche, but > 1 (median 2.1 [1.34-5.67] in those with precocious puberty. Bone age was accelerated by at least 18 months in those with precocious puberty, but it corresponded to their chronological age or was only slightly accelerated in those with premature thelarche. These data thus indicate that premature thelarche and central precocious puberty can be reliably distinguished by the LHRH test and bone age.