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International Journal of Endocrinology
Volume 2012, Article ID 324835, 6 pages
Research Article

Clinical Presentation of Klinefelter's Syndrome: Differences According to Age

1Servicio de Endocrinología y Metabolismo, Unidad Asistencial “Dr. César Milstein”, Buenos Aires, Argentina
2Sección Endocrinología, Crecimiento y Desarrollo, Departamento de Pediatría, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
3División de Endocrinología, Hospital de Niños Dr. Ricardo Gutiérrez and, Centro de Investigaciones Endocrinológicas (CEDIE, CONICET), Buenos Aires, Argentina
4Servicio de Endocrinología, Metabolismo y Medicina Nuclear, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
5Consultorio de Endocrinología, Centro Médico Haedo, Haedo, Argentina
6Sección Andrología, División Endocrinología, Hospital Durand, Buenos Aires, Argentina

Received 29 July 2011; Accepted 8 October 2011

Academic Editor: Ana Claudia Latronico

Copyright © 2012 Néstor Pacenza et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of the study was to establish the characteristics of presentation of 94 patients with Kinelfelter's syndrome (KS) referred to the endocrinologist at different ages. 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. Half of the patients younger than 18 years presented mild neurodevelopmental disorders. The most frequent clinical findings were cryptorchidism in prepubertal patients, and small testes, cryptorchidism, and gynecomastia in pubertal patients. FSH, LH, AMH, and inhibin B levels were normal in prepubertal patients and became abnormal from midpuberty. Most adults were referred for small testes, infertility, and gynecomastia; 43.6% had sexual dysfunction. Testosterone levels were low in 45%. Mean stature was above the 50th percentile, and 62.5% had BMI  kg/m2. In conclusion, the diagnosis of Klinefelter syndrome seems to be made earlier nowadays probably because pediatricians are more aware that boys and adolescents with neuro-developmental disorders and cryptorchidism are at increased risk. The increasing use of prenatal diagnosis has also decreased the mean age at diagnosis and allowed to get insight into the evolution of previously undiagnosed cases, which probably represent the mildest forms. In adults average height and weight are slightly higher than those in the normal population. Bone mineral density is mildly affected, more at the spine than at the femoral neck level, in less than half of cases.