Introduction: McCune Albright syndrome (MAS) is characterised by at least 2 of 3 features: polyostotic fibrous dysplasia (FD), café-au-lait skin pigmentation and autonomous endocrine hyperfunction. Growth hormone excess if present (GH) can worsen symptoms of FD.
Case report: A 3 year old girl presented with vaginal bleeding. A single café-au-lait patch was present (3 cm). A diagnosis of MAS was made, with a c.601>T mutation found in the GNAS gene. Gonadotrophin independent precocious puberty was treated with an aromatase inhibitor. On imaging she had cranial FD encircling the left optic nerve. There were concerns that GH excess associated with FD could compromise her vision. The IGF-I levels were in the upper normal ranges. A GH suppression test reduced the GH from 6.9 to 0.8 ug/l. Due to incomplete GH suppression she had overnight profiling (GH taken at 20min intervals from 8pm to 8am). The GH showed good variability (mean 3.9 μg/l, range 0.79.8 μg/l). In conjunction with a normal growth rate it was deemed to be an acceptable profile. Her height SDS ranged from +0.4 to +1.0 SDS. Two further overnight GH profiles followed by GH suppression tests were repeated at annual intervals. By the third profile the GH did not fall below 1 μg/l either on the overnight profile (mean 4.4 μg/l, range 1.111.8 μg/l) or suppress below 0.5 μg/l on the OGTT. Due to concerns about the impact of excess GH on FD she was commenced on a somatostatin analogue (Lanreotide LA injections), resulting in a reduction of IGF-I to within the mid-normal range for her age.
Conclusion: GH excess in MAS and is associated with a worsening of the fibrous dysplasia. Overnight GH profiling can aid in the diagnosis of GH hypersecretion, particularly when an OGTT is equivocal. This is crucial in patients with craniofacial fibrous dysplasia as early diagnosis and treatment of GH excess may prevent GH excess associated morbidity, specifically vision loss.
07 - 09 Nov 2018
British Society for Paediatric Endocrinology and Diabetes