PP075 - INTERPLAY BETWEEN HEART RATE VARIABILITY AND REVERSE TRIIODOTHYRONINE LEVELS IN EATING DISORDERS: A PILOT STUDY

PP075

INTERPLAY BETWEEN HEART RATE VARIABILITY AND REVERSE TRIIODOTHYRONINE LEVELS IN EATING DISORDERS: A PILOT STUDY

C. Piciocchi¹, D. Sorabella¹, A. Mariano², F. Frigerio³, I. Marini⁴, M. Pasquini⁴, M. Fontana², E. Poggiogalle^1,*

¹Experimental Medicine, ²Biochemical Sciences, Sapienza University, ³Human Sciences and Promotion of the Quality of Life, San Raffaele Open University, ⁴Human Neurosciences, Sapienza University, Rome, Italy

Rationale: The aim of this study was to investigate associations between heart rate variability (HRV) parameters, as a measure of autonomic nervous system, and the ratio between reverse triiodothyronine (rT3) and free triiodothyronine (FT3) levels in patients with anorexia nervosa (AN) and atypical anorexia nervosa (aAN).

Methods: Eligible participants were female inpatients aged 12 years or older with a diagnosis of AN or aAN according to DSM-5.

Anthropometric measurements were collected and body mass index (BMI) was calculated; HRV parameters were assessed. Whole blood samples were collected to determine circulating FT3 and rT3 levels.

Results: Thirty-two participants (AN n= 27, aAN n= 5), mean age 21 (18-24) years, were recruited. Partial correlation analysis controlled for age, revealed that rT3-to-FT3 ratio was positively related with SDNN (ρ 0.403, p 0.025), total power (ρ 0.395, p 0.028), LF power (ρ 0.415, p 0.020), and HF power (ρ 0.366, p 0.043). A tendency was observed between rT3 to FT3 ratio and VLF power (ρ 0.338, p 0.063).

Based on multiple linear regression analyses, the rT3-to-FT3 ratio significantly predicted SDNN (age-adjusted: B 0.428, SE 0.181, p 0.025; BMI-adjusted: B 0443, SE 0.187, p 0.025). Similar findings were observed for total power (age-adjusted model: B 0.010, SE 0.004, p 0.028, BMI-adjusted model: B 0.010, SE 0.005, p 0.029), LF power (age-adjusted: B 0.011, SE 0.004, p 0.020, BMI-adjusted: B 0.011, SE 0.005, p 0.021), and HF power (age-adjusted: B 0.011, SE 0.005, p 0.043, BMI-adjusted: B 0.012, SE 0.006, p 0.047).

Conclusion: Elevated values of time and frequency domains of HRV were observed, consistent with a predominance of vagal tone. Our findings support that the rT3-to-FT3 ratio could be a relevant, energy-related determinant of the sympathetic-vagal imbalance, although its implication in patients with EDs remains to be thoroughly elucidated.

Disclosure of Interest: None declared