title: Correction of Hypothyroidism Leads to Change in Lean Body Mass without Altering Insulin Resistance.
abstract: BACKGROUND
  Hypothyroidism is associated with insulin resistance, dyslipidemia, and abnormal body composition. This study assessed changes in body composition and insulin resistance after thyroxine (T4) replacement in overt hypothyroidism.
  
  
  METHODS
  In this prospective longitudinal study carried out in a tertiary care center, adult nondiabetic patients with overt hypothyroidism were rendered euthyroid on T4. Anthropometry including skinfold thickness (SFT) at the triceps and subscapularis was recorded. Patients underwent testing for fasting plasma glucose, creatinine, serum insulin, T4, thyrotropin (TSH) and body composition analysis by dual-energy X-ray absorptiometry (DEXA) both before and at 2 months after restoration to the euthyroid state.
  
  
  RESULTS
  Twenty-seven patients (20 female and 7 male) aged 35.3 ± 11.0 years (min-max: 17-59 years) with overt hypothyroidism were recruited. Serum T4at the time of recruitment was 48.9 ± 24.6 nmol/l (normal range = 64.4-142 nmol/l). All patients had TSH ≥50 µIU/l. Following treatment, there was a mean body weight reduction of 1.7 kg (p = 0.01). Waist circumference as well as triceps and subscapularis SFT decreased significantly (p < 0.001). There was no change in fat mass (FM), percentage of fat (%FM) or bone mineral content in any of the specified regions or in the body as a whole. In contrast, mean lean body mass (LBM) decreased significantly by 0.8 kg (p < 0.01) in the trunk and 1.3 kg (p < 0.01) in the whole body. Insulin resistance and level of glycemia were not affected by treatment with T4.
  
  
  CONCLUSIONS
  LBM decreases significantly without affecting FM after correction of hypothyroidism. Insulin resistance was not influenced by T4treatment.
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Sangeetha
authors.initials: S
authors.lastname: Sirigiri
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Suresh
authors.initials: S
authors.lastname: Vaikkakara
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Alok
authors.initials: A
authors.lastname: Sachan
authors.affiliation: Department of Biochemistry, Sri Venkateswara Institute of Medical Sciences, Tirupati, India.
authors.forename: P V L N
authors.initials: PV
authors.lastname: Srinivasarao
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Sunil
authors.initials: S
authors.lastname: Epuri
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Anantarapu
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Arun
authors.initials: A
authors.lastname: Mukka
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Srinivasa Rao
authors.initials: SR
authors.lastname: Chokkapu
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Ashok
authors.initials: A
authors.lastname: Venkatanarasu
authors.affiliation: Department of Endocrinology, Tirupati, India.
authors.forename: Ravi
authors.initials: R
authors.lastname: Poojari
keywords: Body composition; Hypothyroidism; Insulin resistance; Lean body mass; Thyroxine