Microcirculation and nadh fluorescence parameters in the skin of patients with overt hypothyroidism and their dynamics after achieving euthyroidism
Ryzhkova E.G., Morgunova T.B., Fadeev V.V.
Background: Hypothyroidism (HT) is associated with cardiovascular and metabolic disorders, which in some cases do not improve with levothyroxine sodium (LT4) replacement therapy.
Objective: Evaluation of microcirculation and reduced nicotinamide adenine dinucleotide (NADH) fluorescence in the skin of patients with newly diagnosed overt HT before and after achieving euthyroidism with LT4.
Materials and methods: Lipid profiles, complete blood counts, interleukin-6 (IL-6) levels, microcirculation, and NADH fluorescence amplitude (AFNADH) were assessed in forearm skin of 50 healthy volunteers and 14 patients with overt HT at rest, upon cooling to 10°C, and upon heating to 35°C and 42°C. The standard deviation (σ) and blood flow variation coefficient (Kv) were calculated, and wavelet analysis was used to determine the amplitudes of microcirculation fluctuations in the neurogenic (An), myogenic (Am), respiratory (Ar), and cardic (Ac) ranges.
Results: In overt hyperthermia, the microcirculation index upon heating to 42°C, Aм, Aс, and σ were lower than in healthy volunteers. No differences were found in other microcirculation parameters, nor in AFNADH at rest, upon cooling and heating to 35°C. After achieving euthyroidism, no statistically significant changes in microcirculation parameters or AFNADH were observed. During hyperthermia, levels of total cholesterol (TC), low-density lipoproteins (LDL), triglycerides, IL-6, and erythrocyte distribution width (RDW) were higher than in healthy volunteers. Positive changes in these parameters were noted after treatment.
Conclusion: Disturbances in cutaneous microcirculation during hyperthermia are manifested by a decrease in peak hyperemia upon heating to 42°C and a reduction in microcirculation variability due to a decrease in Aм and Aс, which persists after achieving euthyroidism. These changes are associated with dyslipidemia, increased IL-6, and RDW, with subsequent improvement during treatment. AFNADH parameters do not differ between patients with HT and healthy volunteers and do not change during treatment.
For citations: Ryzhkova E.G., Morgunova T.B., Fadeev V.V. Microcirculation and nadh fluorescence parameters in the skin of patients with overt hypothyroidism and their dynamics after achieving euthyroidism. Pharmateca. 2026;33(4):249-258. (In Russ.). DOI:
https://dx.doi.org/10.18565/pharmateca.2026.4.249-258
Authors’ contribution: E.G. Ryzhkova – conceptualization, data curation, formal analysis, investigation, methodology development, project administration, visualization, writing – original draft preparation. T.B. Morgunova – project administration, resources provision, supervision, writing – review and editing. V.V. Fadeev – resources provision, supervision, writing -review and editing.
Conflicts of interest: The authors confirm that they have no conflicts of interest to declare.
Funding: The study was conducted without any sponsorship.
Patient Consent for Publication: All patients provided informed consent for the publication of their data.
Authors’ Data Sharing Statement: The data supporting the findings of this study are available upon request from the corresponding author after approval from the principal investigator.
Keywords
hypothyroidism
levothyroxine
skin perfusion
intracellular metabolism
temperature testing
interleukin-6
lipid profile
About the Authors
Ekaterina G. Ryzhkova, Postgraduate Student, Department of Endocrinology and Metabolic Health, N.V. Sklifosovsky Institute of Clinical Medicine, I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia; e.g.ryzhkova@bk.ru; ORCID: https://orcid.org/0000-0003-0069-1692 (corresponding author)T.B. Morgunova, Cand. Sci. (Med.), Associate Professor, Endocrinologist, Professorial Clinic of Endocrinology and Diabetes, Moscow, Russia; tanmorgun@mail.ru; ORCID: https://orcid.org/0000-0003-1500-1586
V.V. Fadeev, Dr. Sci. (Med.), Corresponding Member of the Russian Academy of Sciences, Professor, Department of Internal Medicine, Faculty of Fundamental Medicine, Moscow Scientific Institute of Orthopaedics, Lomonosov Moscow State University, Moscow, Russia; walfad@mail.ru;
ORCID: https://orcid.org/0000-0002-3026-6315
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