Endocrine Abstracts

Background: Bardet Biedl syndrome (BBS) is a rare autosomal recessive disorder caused by ciliary dysfunction. It is characterised by rod cone dystrophy, polydactyly, renal dysfunction, cognitive impairment. Endocrine consequences are thought to include hypogonadism, obesity and polyuria. However little is known about the endocrine and metabolic abnormalities in adult patients.

Methods: One hundred and fifty-four patients with BBS were identified through two national BBS clinics; anthropometric measurements and fasting blood samples were taken in 130 patients. Date are reported as mean±S.E.M.

Results: Eighty-five patients (55.2%) were male. The age was 33.0±1.0 years (range 13–58 years) and BMI was 35.7±0.7; 102 (76.7%) were obese (BMI >30 kg/m²). The prevalence of metabolic syndrome was high (59.4%) and 24(15.6%) BBS patients had type 2 diabetes; one patient had type 1 diabetes. Polycystic ovary syndrome was present in 12/69 (17.4%) females and 35 (27.3%) patients had biochemical evidence of NAFLD.

Most BBS patients were euthyroid (77.2%), 10(6.5%) had hypothyroidism and one had hyperthyroidism. Twenty-four (19%) had subclinical hypothyroidism.

One hundred and two BBS patients (78.4%) were eupituitary. Of the remaining patients, 15 (11.5%) had an isolated low IGF1, five had mild hyperprolactinaemia (prolactin <1000 mIU/l) and seven patients had isolated low prolactin. One patient had significant hyperprolactinemia (prolactin=6391 IU/ml) and subsequent MRI showed pituitary hypoplasia.

Twenty-six (40%) males were hypogonadal (primary in four patients and secondary in 22 patients). Two patients had nephrogenic diabetes insipidus.

Four (3.9%) patients had stage 5 CKD, 4(3.9%) stage 4 CKD and 14 (13.7%) stage 3 CKD. Four patients had functioning renal transplants.

Conclusions: This is the first study to investigate endocrinopathies in a large BBS population. Despite previous reports, generalised pituitary hormone dysfunction is not prevalent but subclinical hypothyroidism and hypogonadism are common. The majority of patients are obese and the prevalence of metabolic syndrome and type 2 diabetes is high.