Premature : Clinical and Laboratorial Assessment by Immunochemiluminescent Assay

ABSTRACT artigo original In order to establish cut-off limits and to distinguish isolated premature thelarche (IPT) from (PP), we evaluated data from 79 girls with premature thelarche, comparing basal and stimulated LH and FSH serum concentrations with those from 91 healthy girls. A GnRH stimulation test was performed in 10 normal girls and in 42 with premature thelarche. Comparison MARIA F. BORGES among groups was performed by Kruskal-Wallis and Dunn’s tests. LH values were significantly greater in girls with IPT than in control groups. Basal go- KÁTIA D. PACHECO nadotropin concentrations were higher in patients with PP than in controls, but ANDRÉIA A. OLIVEIRA not different from patients with IPT. Peak LH levels after GnRH stimulation dis- tinguished those two groups, with a cut-off value of 4.0 IU/L, but still with min- CLÁUDIA V. C. RITA imal overlap. In conclusion, a girl with premature thelarche and LH peak value KARLA D. PACHECO above 4.5 IU/L has, indeed, PP, but values between 3.5 and 4.5 IU/L point to ELISABETE A. M. RESENDE careful follow-up. (Arq Bras Endocrinol Metab 2008;52/1:93-100) BEATRIZ H. J. LARA Keywords: Premature thelarche; GnRH test; Laboratorial assessment; Immu- BEATRIZ P. F ERREIRA nochemiluminescent assay

RESUMO Disciplina de Endocrinologia Telarca precoce: avaliação clínica e laboratorial pelo método imuno- [ Department], quimioluminescente. Faculdade de Medicina da Com o objetivo de estabelecer o valor de corte e distinguir telarca precoce Universidade Federal do isolada (TPI) de puberdade precoce (PP), avaliamos 79 meninas com telarca Triângulo Mineiro, Uberaba, MG, precoce, comparando as dosagens basais e pós-estímulo de LH e FSH com Brasil grupo-controle. O teste de estímulo com GnRH foi realizado em 10 meninas normais e em 42 com telarca precoce. Os testes de Kruskal-Wallis and Dunn foram usados na comparação dos grupos. Os níveis de LH foram significativa- mente mais elevados no grupo com TPI, quando comparados com controles. As gonadotrofinas basais foram mais elevadas naquelas com PP que nos con- troles, mas não diferiram do grupo com TPI. O pico de LH após GnRH distin- guiu estes dois grupos, com valor de corte de 4,0 UI/L, apesar de pequena sobreposição. Concluímos que uma menina com telarca precoce e LH pós-es- tímulo acima de 4,5 UI/L apresenta PP, mas valores entre 3,5 e 4,5 UI/L reque- rem seguimento cuidadoso. (Arq Bras Endocrinol Metab 2008;52/1:93-100)

Descritores: Telarca precoce; Teste de estímulo do GnRH; Avaliação laborato- rial; Ensaio imunoquimioluminescente

INTRODUCTION

REMATURE THELARCHE (PT) is a clinical condition characterized by isolated Pbreast development in girls before 8 years of age. In the absence of other clinical signs of sexual maturation, it has been considered as a variant of nor- ABE&M todos os direitos reservados mal development, and it is more prevalent during the first two years of life © when the hypothalamic-pituitary-gonadal (HPG) axis has not been sup- Recebido em 29/08/2007 pressed yet (1-3). Aceito em 02/10/2007 copyright

Arq Bras Endrocrinol Metab 2008;52/1 93 Premature thelarche Borges et al.

The pathophysiological mechanisms that cause PT SUBJECTS AND METHODS are unknown and have been hypothesized to result from 1) increased sensitivity to (4,5); Subjects The research protocol was approved by the Ethics 2) increased (E2) levels (6); 3) transient estro- gen secretion by follicular ovarian cysts (4); 4) increased Committee of the Faculdade de Medicina da Universi- estrogen production from adrenal precursors (7); 5) dade Federal do Triângulo Mineiro, Uberaba, (Brazil).