BACKGROUND:Neuromuscular symptoms and impaired muscle energy metabolism have been described in subclinical hypothyroidism (sHT). AIM: The aim of the study was to evaluate the energy and substrate response to exercise in sHT patients using a standardized protocol and to test the effect of L-T(4) replacement in a double-blind, randomized, placebo-controlled fashion. PATIENTS AND METHODS: We studied 23 sHT patients and 10 matched euthyroid controls. Oxygen uptake (VO(2)), carbon dioxide output, and heart rate were measured during incremental step-up exercise. Blood glucose, lactate, pyruvate, free fatty acid, glycerol, and beta-hydroxybutyrate concentrations were measured at rest, every 2 min during exercise, and during 20 min of recovery. The exercise protocol was repeated after 6 months of placebo or L-T(4)-restored euthyroidism. RESULTS:Maximal power output (P = 0.02) and VO(2) max (P = 0.04) were reduced in sHT, and, with increasing workload, patients achieved higher heart rates (P < 0.03) at VO(2) values equivalent to those of controls. The respiratory quotient increments were significantly higher in patients than controls (P < 0.04). Blood lactate and pyruvate and their ratio rose with a steeper slope (P < 0.0001, P < 0.001, and P < 0.01, respectively) in patients than controls. Resting plasma free fatty acid and blood glycerol levels were significantly higher in patients than controls (P < 0.0003 and P < 0.003, respectively) throughout baseline, exercise, and recovery. L-T(4) replacement, while improving neuromuscular symptoms, did not produce significant changes in the energy or substrate response to exercise. CONCLUSIONS: The response to exercise is altered both in terms of tolerance and pattern of substrate utilization in sHT patients. Restoring stable euthyroidism does not correct this defect over a 1-yr period.
RCT Entities:
BACKGROUND:Neuromuscular symptoms and impaired muscle energy metabolism have been described in subclinical hypothyroidism (sHT). AIM: The aim of the study was to evaluate the energy and substrate response to exercise in sHT patients using a standardized protocol and to test the effect of L-T(4) replacement in a double-blind, randomized, placebo-controlled fashion. PATIENTS AND METHODS: We studied 23 sHT patients and 10 matched euthyroid controls. Oxygen uptake (VO(2)), carbon dioxide output, and heart rate were measured during incremental step-up exercise. Blood glucose, lactate, pyruvate, free fatty acid, glycerol, and beta-hydroxybutyrate concentrations were measured at rest, every 2 min during exercise, and during 20 min of recovery. The exercise protocol was repeated after 6 months of placebo or L-T(4)-restored euthyroidism. RESULTS: Maximal power output (P = 0.02) and VO(2) max (P = 0.04) were reduced in sHT, and, with increasing workload, patients achieved higher heart rates (P < 0.03) at VO(2) values equivalent to those of controls. The respiratory quotient increments were significantly higher in patients than controls (P < 0.04). Blood lactate and pyruvate and their ratio rose with a steeper slope (P < 0.0001, P < 0.001, and P < 0.01, respectively) in patients than controls. Resting plasma free fatty acid and blood glycerol levels were significantly higher in patients than controls (P < 0.0003 and P < 0.003, respectively) throughout baseline, exercise, and recovery. L-T(4) replacement, while improving neuromuscular symptoms, did not produce significant changes in the energy or substrate response to exercise. CONCLUSIONS: The response to exercise is altered both in terms of tolerance and pattern of substrate utilization in sHT patients. Restoring stable euthyroidism does not correct this defect over a 1-yr period.
Authors: Martin Feller; Marieke Snel; Elisavet Moutzouri; Douglas C Bauer; Maria de Montmollin; Drahomir Aujesky; Ian Ford; Jacobijn Gussekloo; Patricia M Kearney; Simon Mooijaart; Terry Quinn; David Stott; Rudi Westendorp; Nicolas Rodondi; Olaf M Dekkers Journal: JAMA Date: 2018-10-02 Impact factor: 56.272
Authors: Richard Birtwhistle; Kate Morissette; James A Dickinson; Donna L Reynolds; Marc T Avey; Francesca Reyes Domingo; Rachel Rodin; Brett D Thombs Journal: CMAJ Date: 2019-11-18 Impact factor: 8.262
Authors: P Rana; G Sripathy; A Varshney; P Kumar; M Memita Devi; R K Marwaha; R P Tripathi; S Khushu Journal: J Endocrinol Invest Date: 2011-04-20 Impact factor: 4.256
Authors: D Gallo; E Piantanida; G Veronesi; A Lai; L Sassi; V Lombardi; E Masiello; P Premoli; E Bianconi; C Cusini; S Rosetti; M L Tanda; A Toniolo; M Ferrario; L Bartalena Journal: J Endocrinol Invest Date: 2017-04-22 Impact factor: 4.256
Authors: A Tanriverdi; B Ozcan Kahraman; I Ozsoy; F Bayraktar; B Ozgen Saydam; S Acar; E Ozpelit; B Akdeniz; S Savci Journal: J Endocrinol Invest Date: 2018-11-19 Impact factor: 4.256
Authors: Daniele L Ignacio; Diego H S Silvestre; Elena Anne-Palmer; Barbara M L C Bocco; Tatiana L Fonseca; Miriam O Ribeiro; Balázs Gereben; Antonio C Bianco; Joao P Werneck-de-Castro Journal: Thyroid Date: 2017-02-10 Impact factor: 6.568