Persistent cellular metabolic changes after hemithyroidectomy for benign euthyroid goiter.
BACKGROUND
The significance of perturbations of thyroid-stimulating hormone (TSH) and thyroid hormones within the laboratory reference ranges after hemithyroidectomy is unknown. Our aim was to examine changes in TSH and thyroid hormones after hemithyroidectomy for benign euthyroid goiter, focusing on tissue response by examining the mitochondrial membrane potential (MMP) of peripheral blood mononuclear cells (PBMCs) and basal oxygen consumption (V˙O2).


METHODS
In a prospective study on 28 patients and controls, we examined serum TSH and thyroid hormones before hemithyroidectomy and 1, 3, 6 and 12 months after hemithyroidectomy for benign euthyroid goiter. In the hemithyroidectomy group, flow cytometry was used to measure the MMP of tetramethylrhodamine methyl ester (TMRM)- and MitoTracker Green (MTG)-stained PBMCs, and V˙O2 was measured by an Oxycon Pro apparatus.


RESULTS
One year after hemithyroidectomy, TSH had increased from a median of 0.97 mIU/l (interquartile range, IQR: 0.69-1.50 mIU/l) to 2.10 mIU/l (IQR: 1.90-3.00 mIU/l; p < 0.001); free thyroxine (fT4) had decreased from a median of 16.0 pmol/l (IQR: 14.9-17.0 pmol/l) to 14.8 pmol/l (IQR: 14.1-16.4 pmol/l; p = 0.009), whereas total triiodothyronine variations did not differ from those in controls. Concomitantly, the MMP of TMRM- and MTG-stained PBMCs was increased by 58% (p < 0.001) and 22% (p = 0.008), respectively. V˙O2 was increased by 14% (p = 0.01).


CONCLUSIONS
Hemithyroidectomy for benign euthyroid goiter induced persistently increased TSH and decreased fT4, sustained mitochondrial hyperpolarization and increased V˙O2. Our results demonstrate a decrease after hemithyroidectomy of the metabolic state to which the individual is adapted, with persistent cellular metabolic changes in a hemithyroidectomized patient group which is normally considered clinically and biochemically euthyroid.
Department of Otorhinolaryngology, Head and Neck Surgery, Køge Hospital, Region Zealand, Køge, Denmark.
Tina
T
Toft Kristensen
Department of Clinical Pathology, Næstved Hospital, Region Zealand, Næstved, Denmark.
Jacob
J
Larsen
Department of Clinical Biochemistry, Næstved Hospital, Region Zealand, Næstved, Denmark.
Palle Lyngsie
PL
Pedersen
Department of Gynecology and Obstetrics, Næstved Hospital, Region Zealand, Næstved, Denmark.
Anne-Dorthe
AD
Feldthusen
Department of Clinical Biochemistry, Næstved Hospital, Region Zealand, Næstved, Denmark.
Christina
C
Ellervik
Department of Otorhinolaryngology, Head and Neck Surgery, Køge Hospital, Region Zealand, Køge, Denmark.
Søren
S
Jelstrup
Department of Internal Medicine, Næstved Hospital, Region Zealand, Næstved, Denmark.
Jan
J
Kvetny
Hypothyroidism; Mitochondrial function; Thyroid hormone; Thyroidectomy; Thyrotropin