Endocrine Abstracts

Introduction: Monosomy 18q represents a partial deletion of the long arm of chromosome 18, with an estimated prevalence of 1:100 000. This syndrome is characterized by a highly variable phenotype. The symptoms and their severity depend on which part of the chromosome is missing. Most common manifestations are hypotonia, developmental delay, short stature, growth hormone deficiency, hearing loss and external ear anomalies, intellectual disability, palatal defects, dysmorphic facial features, skeletal anomalies, and mood disorders.

Case presentation: The patient, a 14 year old male, was first evaluated at the Pediatrics Department due to mild cognitive delay, postnatal proportional short stature, and absence of pubarche. He was born at 39 weeks old, with abnormal weight (46 cm, < 5th centile, –2.1 SDS). He had dysmorphic features, hypotonia, his heigh was 141 cm (< 5th percentile, – 2.7 SDS) and his body mass index (BMI) was 14.8 ( –2.58 SDS) and Tanner stage 1. The lab tests showed hemoglobin 15.4 g/dl (13.9 – 16.3), IGFBP-3 3.22 (3.3 – 10), IGF1 91 (173 – 414), LH 1.2 mIU/ml (1.2 – 8.6), FSH 1.6 mIU/ml (1.3 – 19.3), total testosterone 0.4 ng/ml (1.6 – 7.5), free testosterone 0.36 pg/ml (0.3 – 1.7), TSH 3.23 mUI/ml (0.38 – 5.33), with negative celiac disease screening, normal phospho-calcium metabolism, hemoglobin, renal, glucose and lipid profile. The bone maturation was 3 years delayed concerning his chronological age. The clonidine test suggested GH insufficiency. Cerebral MRI was unremarkable. Genetic study: 18q23 deletion in an array and confirmed in FISH. Karyotype 46, XY, del (18) (q23). He started supplementation with testosterone 50 mg every 4 weeks. He transitioned to adult Endocrinology department at 18 years old and maintained testosterone supplementation. He had a normal testes. Testicular ultrasound: normal testicular. Echocardiogram and renal ultrasound, performed to screen for comorbidities associated with this syndrome, found no changes. In the last evaluation: Weight: 41.5 kg (< 5th percentile, – 4.1 SDS), height: 161.5 cm (< 5th percentile, –2.1 SDS). Tanner 5. Hormonal evaluation showed normal gonadotropins and testosterone, prompting testosterone deficiency reassessment.

Discussion: This case shows an uncommon cause of GH insufficiency. In patients with 18q23 deletion syndrome, GH deficiency is common, and there are case reports of concomitant hypothyroidism. In this case, the patient had, in addition to GH deficiency, an initial hypogonadotropic hypogonadism which has not been previously described.