Obesity in children with narcolepsy: metabolic and endocrine comorbidities

Abstract

Study Objectives Narcolepsy with cataplexy is associated with obesity in children. We proposed to assess whether metabolic complications were linked to narcolepsy regardless of obesity. The second aim of the study was to compare endocrine comorbidities in obese children with narcolepsy and control patients. Methods We performed a case-control study in Pediatric Sleep Unit and Pediatric Endocrinology Unit of Woman Mother Child Hospital (Lyon, France) comparing twenty-two children with narcolepsy with 22 sex-, pubertal stage-, and BMI-matched non-syndromic obese patients. Clinical examination, biological measurements including an oral glucose tolerance test (OGTT) and abdominal ultrasound were performed. Results No difference regarding glucidic, lipid profile, hepatic, respiratory and cardiovascular parameters were found between narcoleptic and control subjects. Insulin sensitivity did not differ between the two groups. Control patients had more first-degree family history of overweight or obesity than children with narcolepsy (83% vs 50%, p=0.05). Prevalence of precocious puberty in children with narcolepsy was not higher than in control subjects, but all the cases of advanced puberty involved children with narcolepsy who were diagnosed before 11 years old. All cases of central hypothyroidism belong to the narcoleptic group who presented lower TSH and fTA values compared to control children (respectively p=0.03 and p= 0.001). Conclusions No difference regarding metabolic complications was found between children with narcolepsy and control subjects. Thus, metabolic disorders may be related to weight gain rather than a narcolepsy specific risk. The presence of hypothyroidism and advanced puberty suggest a global involvement of hypothalamic structures in children with narcolepsy.