Endocrine Abstracts (2017) 51 P031 | DOI: 10.1530/endoabs.51.P031

Early puberty in Klinefelter syndrome

Pooja Vasista, James Greening & Vaya Tziaferi


Leicester Royal Infirmary, Leicester, UK.


Introduction: Klinefelter Syndrome (KS) is related to late puberty and infertility. Early puberty in KS is a rare occurrence; a case of early puberty in KS is presented.

Case report: A 10-year old boy, diagnosed with KS (47,XXY) during investigations for learning difficulties, was referred to the endocrine clinic with a history of facial acne since the age of 8 years. His examination showed pubic hair (stage 3) with testicular volume 4–5 ml on both sides. Serum Gonadotrophins were high, compatible with the diagnosis of KS, with satisfactory serum testosterone level. One year later, he was in stage 4 for pubic hair and stage 3 for axillary hair, while testicular size remained the same. His height velocity was 4.25 cm/year. By the age of 12 years, his height velocity had slowed down to 2 cm/year. Tanner staging showed stage 5 for genitalia with testicular size remaining unchanged. Bone age at this stage was 16 years, indicating precocious puberty. Subsequently, investigations were carried out to rule out neoplastic causes of precocious puberty as previously reported in KS, including tumour markers, Chest X-ray, abdominal US scan and MRI brain, which were reported to be normal. Screening for mutations in exons 8 and 9 of GNAS1 gene was negative. It was concluded that this boy had undergone central precocious puberty (Table 1).

Table 1
Age10 years11 years12 years
Pubic hair stage3+44
Genitalia stage5
Testicular volume4–5 ml4–5 ml4–5 ml
Height velocity (cm/year)4.252
LH (IU/l)212844
FSH (IU/l)456266
Testosterone (nmol/l)6.27.36.2
hCG (IU/l)47
Alpha-foetoprotein< 2< 2
17OHP (nmol/l)3.32.6
DHEA (nmol/l)2.94.3
Androstenedione (nmol/l)1.32.4

Conclusion: Precocious puberty in children with KS is rare; the common causes are idiopathic central precocious puberty and extragonadal germ cell tumours. In this case the diagnosis was made in retrospect but clinicians should be aware to investigate for germ cell tumours in children with KS presenting in early puberty if there are signs of virilisation even if testicular volume is small.

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