Horm Metab Res 2010; 42(5): 324-327
DOI: 10.1055/s-0030-1248261
Original Basic

© Georg Thieme Verlag KG Stuttgart · New York

Subclinical Hypothyroidism Affects Mitochondrial Function

J. Kvetny1 , L. Wilms2 , P. L. Pedersen3 , J. Larsen4
  • 1The Mitochondrial Research Unit, Department of Internal Medicine, Faculty of Health Sciences, University of Copenhagen, Denmark, Naestved Sygehus, Naestved, Denmark
  • 2Department of Pediatrics, Naestved Hospital, Naestved, Denmark
  • 3Department of Clinical Biochemistry, Naestved Hospital, Naestved, Denmark
  • 4Department of Clinical Pathology, Naestved Hospital, Naestved, Denmark
Further Information

Publication History

received 08.10.2009

accepted after second revision 21.01.2010

Publication Date:
22 February 2010 (online)

Abstract

The aim of the present study was to examine mitochondrial function in cells from persons with subclinical hypothyroidism and euthyroid controls. The participating persons were examined clinically and had basal oxygen consumption (VO2) determined. The concentrations of thyroid hormones and thyrotropine stimulating hormone were determined, and mitochondrial function in isolated mononuclear blood cells was examined by enzymatic methods [citrate synthase activity (CS)] and by flow cytometry (mitochondrial membrane potential by TMRM fluorescence and mitochondrial mass by MTG fluorescence). The ratio of T4/T3 was lowered in subclinical hypothyroidism patients compared to controls (2.5±0.5 vs. 2.9±0.4, p=0.005). VO2 was increased in persons with subclinical hypothyroidism compared to controls (adolescents: 134±27 ml O2/min*m2 vs. 119±27 ml O2/min*m2, p=0.006, adults: 139±14 ml O2/min*m2 vs. 121±17 ml O2/min*m2, p=0.001). The mitochondrial function, represented by citrate synthase activity, MTG, and TMRM fluorescence were all increased (CS in subclinical hypothyroidism vs. controls: 0.074±0.044 nmol/mg*min vs. 0.056±0.021 nmol/mg*min, p=0.005; MTG fluorescence in subclinical hypothyroidism vs. controls: 7 482±1 733 a.u. vs. 6 391±2 171 a.u., p=0.027; TMRM fluorescence in subclinical hypothyroidism vs. controls: 1 3449±3 807 a.u. vs. 1 1733±4 473 a.u, p=0.04). Our results indicate an increased mitochondrial stimulation, eventually caused by increased deiodination of T4 to intracellular bioactive iodothyronines in adults and adolescents with subclinical hypothyroidism.

References

Correspondence

J. Kvetny, MD.,DMSc 

Chief Physician, Ass. Prof. Endocrinological Clinic

Department of Internal Medicine & Faculty of Health Sciences

University of Copenhagen

Denmark

Naestved Hospital

4700 Naestved

Denmark

Phone: +45/56/514136

Fax: +45/56/513770

Email: [email protected]