Síndrome de Klinefelter en las distintas edades: experiencia multicéntrica

klinefelter syndrome (ks) is the most common chromosomal aberration among men, with an estimated prevalence of 1:600 newborns. it is an x chromosome polysomy, with x disomy being the most common variant (47,xxy). the aim of this study was to establish the characteristics of ks presentation at different ages, including signs and symptoms, laboratory parameters and other diagnostic tests. the diagnosis of ks was more frequent in the age group between 11 and 20 years (46.8%). most of the patients (83.7%) showed the classic 47,xxy karyotype and 7.1% showed a 47,xxy/46,xy mosaicism. while mean prepubertal height was not different from the control population, it was significantly higher at puberty. patients consulted most frequently for small testes, infertility and cryptorchidism. in four cases the diagnosis was prenatal. 50% of our patients younger than 18 years presented neurocognitive disorders. the more frequent clinical findings were cryptorchidism in prepubertal patients; small testes, cryptorchidism and gynecomastia in pubertal patients. all our patients in tanner stage iii or more presented small testes. fsh and lh levels were normal in prepubertal patients and increased abnormally at puberty. on the other hand, most adults consulted for small testes, infertility and gynecomastia. 43.6% of patients had decreased libido, sexual and/or ejaculatory dysfunction. in adults average height (178.8 ± 9.0 cm) and weight (83.6 ± 21.0 kg), were higher than in the normal population, however 8 patients (19%) had a height less tan 170 cm. there was 62.5% of overweight / obesity (bmi ≥ 25.0 kg/m2) in the whole group of adult patients. 35.2% had eunuchoid proportions. all patients had testicular hypotrophc, with a median testicular volume of 3.5 ml (range 1-8 ml). total testosterone (tt) levels were normal in 45% of adult patients, showing significant correlation with age. all patients aged 40 or more years had subnormal tt levels. in patients who underwent semen analysis, severe