ESPE Yearbook of Paediatric Endocrinology

Brief Summary: this longitudinal study found no statistical difference between boys and girls regarding the timing of increase in nocturnal luteinizing hormone concentrations.

Puberty results from a gradual increase in GnRH secretion, that can be monitored by urinary gonadotropin measurements. Timing of normal puberty, initially described by Marshal and Tanner, is characterized by an important individual variability in humans^1,2. The difference in puberty timing between boys and girls as well as the higher incidence of reported precocious puberty in girls^3,4, compared to boys and delayed puberty in boys^5,6 compared to girls remain unexplained.

The aim of this study was to investigate the temporal association between activation of the hypothalamic-pituitary-gonadal axis, evaluated by urinary LH, and clinical signs of puberty onset in both sexes. Thirty subjects were included. They were examined by a single observer every 3 to 4 months during 5.5 and 5.8 years on average. Participants provided 24h-urine sample divided into nocturnal sleep and waketime at each visit for determination of LH concentration (U-LH). The cutoff level used for the determination of the onset of puberty was determined at 0.7 U/L.

The initial increase of U-LH concentrations was detectable only in nocturnal sleeptime samples and occurred at around the same age (9-10 years of age) in both sexes. The time between this gonadotropin increase and the appearance of the first clinical signs of puberty was significantly longer in boys (1.5 years) than in girls (0.1 years).

In conclusion, this study showed a sex-independent increase in urinary LH at age 9-10 in a small cohort, with a longer time span to clinical puberty in boys. This suggests that testes could require longer gonadotropin stimulation before reaching tanner stage 2 compared to breasts. However, one cannot exclude that breast development observed in some girls might initially be isolated thelarche or adipomastia.

References: 1. Marshall WA, Tanner JM. Variations in pattern of pubertal changes in girls. Arch Dis Child. 1969;44(235): 291-303.2. Marshall WA, Tanner JM. Variations in pattern of pubertal changes in boys. Arch Dis Child. 1970;45(239): 13-23.3. Bridges NA, Christopher JA, Hindmarsh PC, Brook CG. Sexual precocity: sex incidence and aetiology. Arch Dis Child. 1994;70(2):116-118.4. Chemaitilly W, Trivin C, Adan L, Gall V, Sainte-Rose C, Brauner R.Central precocious puberty: clinical and laboratory features. ClinEndocrinol. 2001;54(3):289-294.5. Bourguignon JP. Growth and timing of puberty: reciprocal effects. Horm Res. 1991;36(3-4):131-135.6. Sedlmeyer IL, Palmert MR. Delayed puberty: analysis of a large caseseries from an academic center. J Clin Endocrinol Metab. 2002;87(4):1613-1620.