Elevated Regional Lipolysis in Hyperthyroidism

• Published in: The journal of clinical endocrinology and metabolism Vol. 87; no. 10; pp. 4747 - 4753
• Main Authors: Riis, Anne Lene Dalkjær, Gravholt, Claus Højbjerg, Djurhuus, Christian Born, Nørrelund, Helene, Jørgensen, Jens Otto Lunde, Weeke, Jørgen, Møller, Niels
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01.10.2002
• Subjects: Abdomen; Adipose Tissue - blood supply; Adipose Tissue - metabolism; Adult; Antithyroid Agents - therapeutic use; Biological and medical sciences; Blood Flow Velocity; Endocrinopathies; Energy Metabolism; Fatty Acids, Nonesterified - blood; Female; Femur; Food; Glucose Clamp Technique; Glycerol - blood; Humans; Hyperinsulinism; Hyperthyroidism - drug therapy; Hyperthyroidism - metabolism; Lipolysis; Medical sciences; Methimazole - therapeutic use; Microdialysis; Middle Aged; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Thyroid. Thyroid axis (diseases); Triiodothyronine - blood; Endocrinopathy; Immunopathology; Pancreatic hormone; Adipose tissue; Pathophysiology; Hyperthyroidism; Thigh; Thyroid diseases; Autoimmune disease; Insulin; Lipolysis; Abdomen; Target tissue resistance; Graves disease; Subcutaneous tissue; Comparative study
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2002-020174

Hyperthyroidism is characterized by increased levels of circulating free fatty acids (FFA) and increased lipid oxidation, but it is uncertain which regional fat depots contribute. The present study was designed to define the participation of femoral and abdominal fat stores in the overall stimulation of lipolysis in hyperthyroidism in the basal state and during insulin stimulation. We studied nine women with newly diagnosed hyperthyroidism (HT) and after (euthyroidism, ET) medical treatment with methimazol and compared with eight control subjects (CTR). All subjects were studied in the postabsorptive state and during a 3-h hyperinsulinemic euglycemic clamp with microdialysis catheters sc in the abdominal and femoral adipose tissue. Before treatment, patients had elevated circulating concentrations of triiodthyronine, FFA, and glycerol. Levels of interstitial glycerol (μmol/liter) in abdominal adipose tissue [485 ± 24 (HT), 226 ± 20 (ET) (P < 0.001), 265 ± 34 (CTR) (P < 0.001)] and in femoral adipose tissue [468 ± 41(HT), 245 ± 29 (ET) (P < 0.01), 278 ± 31(CTR) (P < 0.005)] were elevated in the basal hyperthyroid state, and these differences prevailed during the glucose clamp [230 ± 23 (HT), 113 ± 13 (ET) (P < 0.01), 132 ± 22(CTR) (P < 0.01) and 303 ± 39 (HT), 122 ± 15 (ET) (P < 0.01), 166 ± 21(CTR) (P < 0.01)]. These results suggest that femoral and abdominal adipose tissue contribute equally to the excessive rate of lipolysis in hyperthyroidism and that both tissues are resistant to the actions of insulin.