Endocrine Abstracts

Background: Нypothyroidism (HT) is characterized by decreased overall energy expenditure and the basal metabolic rate. The reduced form of nicotinamide adenine dinucleotide (NADH) fluorescence in the tissue was shown to provide important information on the metabolic state of the mitochondria in terms of energy production. We hypothesize that the intensity of skin NADH fluorescence is associated with impaired energy metabolism in HT. The aim of this study was to evaluate the parameters of NADH fluorescence in the skin as potential biomarkers of impaired energy metabolism in HT.

Methods: We conducted a prospective controlled clinical experimental study. Twenty one patients with HT (7 with newly diagnosed and 14 with decompensated HT) along with sex - and body mass index (BMI) - matched 21 healthy controls (HCs) were recruited. Body temperature (T_body), local skin temperature (T_skin), HR (heart rate), thyroid stimulating hormone (TSH) and free T4 (FT4) were measured in all subjects. Skin NADH fluorescence was assessed by laser fluorescence spectroscopy (365 nm radiation source) on the dorsal forearm at rest (NADH_rest) and during local heating up to 35^oC (NADH_heat). The difference between NADH_heat and NADH_rest (ΔNADH_heat) was also calculated. To compare values between the HCs and the HT groups, the Student’s t-test or Mann-Whitney U test were used when appropriate. Data are presented as the mean±SD.

Results:

Conclusion: HT is characterized by an increase in the intensity of skin NADH fluorescence at rest and its increased utilization during a thermal test. These variables can be used as new promising markers of impaired energy metabolism in hypothyroidism.