Endocrine Abstracts

Introduction: Most of the information about childhood Klinefelter syndrome (KS) comes from newborn-screening follow-up programmes. A recent study of developmental progress in antenatally-identified KS boys has shown little difference from the reference population. Therefore, how do those boys referred to paediatric clinics differ from those in the community? How should care be planned in endocrine clinics?

Patients and Methods: A multidisciplinary clinic was established in 2009 for KS boys and extended with a joint adult transition service in 2015. 133 antenatal and postnatal referrals were received. The clinic database was analysed from 2009-2024 to examine the referral demographics and requirements for medical and other interventions.

Results: In 133 boys, the karyotypes were: 47,XXY (n = 110, 82.7%); 48,XXXY (n = 2, 1.5%); 49,XXXXY, (n = 9, 6.8%); 48,XXYY (n = 10, 7.5%); mosaic 46,XY/47,XXY (n = 1, 1%); 47,XYY (n = 1, 1%). In the 47,XXY boys (n = 110), [excluding the 21 (15.8%) diagnosed antenatally], the indication for karyotyping was: learning, speech or developmental delay 72 (65.5%); ambiguous genitalia 7 (6.4%); pubertal delay 2 (1.8%); dysmorphic features 8 (7.3%). In these XXY boys, 78 (71%) had learning difficulties, an Education, Health and Care Plan (EHCP) being required in 51 (46.4%). 57 (51.8%) had speech delay, 34 (31%) receiving therapy. Whereas in those diagnosed-antenatally (n = 21), only 4 (19 %) had learning difficulties, 3 (14.3 %) requiring an EHCP, and only 4 (19%) had speech delay needing therapy. Almost all the boys with complex karyotypes had speech and learning delay. Testosterone replacement therapy was required in 57.1% (n = 75), indications being: micropenis 8.3% (n = 11), gynaecomastia 21.1% (n = 28), pubertal boost 15% (n = 20), low bone mineral density 6.0% (n = 8), and low testosterone levels 6.0% (n = 8). 53.4% (n = 71) had reached adult height, median 180 cm (IQR: 11.9), range 152.5-200 cm. The median follow-up was 4.8 years (IQR: 5.5) range 0.31-12.4 years. In 58% (n = 77), transition to adult endocrinology had been completed.

Conclusions: The range of additional complex needs of boys with KS and variants referred to paediatric endocrine clinics differs markedly from those of unrecognised KS boys in the community and those antenatally-diagnosed. This highlights the need for establishing both specialist and transition clinics with multidisciplinary input.