title: Presence of brown adipose tissue in an adolescent with severe primary hypothyroidism.
abstract: BACKGROUND
  Brown adipose tissue (BAT) generates heat during adaptive thermogenesis in response to cold temperature. Thyroid hormone (TH) receptors, type 2 deiodinase, and TSH receptors are present on brown adipocytes, indicating that the thyroid axis regulates BAT. It is unknown whether absent TH in humans would down-regulate development of BAT and its thermogenic function.
  
  
  OBJECTIVE
  The objective of the study was to examine BAT by magnetic resonance imaging (MRI) and infrared thermal imaging (IRT) in a pediatric patient with severe primary hypothyroidism before and after TH treatment.
  
  
  METHODS
  This study was a case report with longitudinal follow-up in a tertiary center.
  
  
  METHODS
  BAT fat fraction (FF) by MRI and skin temperature by IRT were measured.
  
  
  RESULTS
  An 11.5-year-old female was severely hypothyroid (TSH, 989 μIU/mL; free T4, 0.10 ng/dL; low thyroglobulin, 3.0 ng/mL). Low MRI measures of FF (56.1% ± 3.7%) indicated that BAT was abundantly present in the supraclavicular fossa. IRT showed higher supraclavicular temperature (36.0°C ±0.16°C) than the suprasternal area (34.3°C ± 0.19°C). After 2 months of TH replacement, she was euthyroid (TSH, 4.3 μIU/mL; free T4, 1.49 ng/dL; T3, 102 ng/dL) at which time supraclavicular BAT decreased (increased FF 60.7% ± 3.8%). IRT showed a higher, more homogeneous skin temperature throughout the upper thorax (supraclavicular, 37.1°C ± 0.23°C; suprasternal, 36.4°C ± 0.13°C). The overall size of the supraclavicular fat depot decreased from 84.79 cm(3) to 41.21 cm(3).
  
  
  CONCLUSIONS
  These findings document the presence of BAT and thermogenesis in profound hypothyroidism and suggest a role for TSH and/or TRH as a potential regulator of BAT.
authors.affiliation: Department of Pediatrics (M.S.K., M.E.G., V.G.), Division of Endocrinology (M.S.K., M.E.G.), and Department of Radiology (H.H.H., P.C.A., V.G.), Children's Hospital Los Angeles; and The Saban Research Institute (M.S.K., H.H.H., M.E.G., V.G.), Los Angeles, California 90027.
authors.forename: Mimi S
authors.initials: MS
authors.lastname: Kim
authors.forename: Houchun H
authors.initials: HH
authors.lastname: Hu
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Aggabao
authors.forename: Mitchell E
authors.initials: ME
authors.lastname: Geffner
authors.forename: Vicente
authors.initials: V
authors.lastname: Gilsanz
mesh_terms: D002001:Adipose Tissue, Brown / Q000378:metabolism* / Q000473:pathology*; D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000378:metabolism* / Q000473:pathology*; D007259:Infrared Rays; D008279:Magnetic Resonance Imaging; D012720:Severity of Illness Index; D022722:Thermogenesis / Q000502:physiology*