Endocrine Abstracts

We present the case history of a 33-year-old male with Noonan syndrome diagnosed at 2 months of age, as he had typical facial features (hypertelorism, ptosis, low set ears, and small pointed chin), a heart murmur and bilateral cryptorchidism. At 22 months he underwent patent ductus arteriosus closure and at 24 months, the left testis was excised, for testicular torsion. He had learning difficulties and attended a special needs school and was intermittently reviewed in the paediatric clinic. At 13 years he was noted to be pre-pubertal, and there was no pubertal growth spurt. At 16 years, he was thought to be in early puberty. However, by 18 years, he did not have significant development of secondary sexual characteristics and had a bone age of 13–14 years. At that point he was commenced on i.m. testosterone (sustanon, 50 mg, 4 weekly). Owing to lack of parenteral support, non-compliance with treatment, and non-attendance to clinics, he did not receive testosterone replacement regularly.

By 22 years, he was 165 cm tall and was reviewed in the adult endocrine clinic with absent secondary sexual features, low libido, micropenis, chest wall deformity, and reduced muscle bulk. Investigations revealed low testosterone (1.1 nmol/l; NR 9.0–32). DEXA bone scan revealed osteoporosis (T score <−3.0). Associated vitamin D deficiency was treated. The patient was commenced on i.m. testosterone undecanoate (1000 mg, 12 weekly). Testosterone levels normalised (10–22 nmol/l) and this contributed to wellbeing, increased body hair and musculature.

This case report highlights the difficulties associated with recognition of delayed puberty in conditions like Noonan syndrome (complicated by cryptorchidism). Further, timely initiation of testosterone is vital in order to prevent osteoporosis. Patients with Noonan syndrome need regular follow up throughout childhood and puberty and into adulthood, in specialist multidisciplinary clinics.