Endocrine Abstracts

Introduction: Within our single centre, the referral rate from the endocrine hypertension clinic to the sleep clinic is high. We have also observed a particular metabolic profile of those patients including raised normetanephrines which subsequently improve after treatment for sleep apnoea.

Illustrative cases: 56 year old man with a BMI of 33 kg/m² and multiple complications of obesity including NAFLD, gallstones and loss of libido. He was rarely refreshed after sleep and his partner confirmed loud snoring. His 24 hour urinary normetanephrines were raised at 11.2umol/24h (NR0-3.8) on one sample. Sleep apnoea was confirmed by the respiratory team and after treatment his normetanephrines normalised becoming normotensive on single agent therapy. 34 year old man with a BMI 42.4 kg/m² seen in clinic with headaches, hypertension, hypogonadotropic hypogonadism, raised urinary normetanephrine (peak of 12.3umol/24h) and plasma normetanephrine (1250 pmol/l NR <1180). His partner had witnessed many concerning apnoeas overnight and reported significant daytime somnolence. He was reviewed by the respiratory team who started CPAP and his plasma normetanephrines returning to within the normal reference range.

Discussion: The current theory is that the relationship between metabolic profile and the intermittent hypoxia experienced during sleep apnoea is bidirectional. Elevated sympathoadrenal activity may explain the increased cardiovascular morbidity associated with obstructive sleep apnoea.

Conclusion: We are currently in discussion with our respiratory, biochemistry and statistician colleagues to help design a feasibility study to investigate:

• Metabolic status assessment of patients seen in the sleep clinic at diagnosis and after establishment of appropriate treatment.

• We would like to assess 24 hour blood pressure, urinary/plasma metanephrines, fasting glucose/HbA1C, markers of inflammation (CRP, TNF-alpha, IL-6), an anterior pituitary profile, lipid profile and renin/aldosterone.

• Ideally, we would also like to assess pulse wave velocity and 24 hour ECGs.