Total thyroxine, triiodothyronine, and thyrotropin concentrations during acute nonthyroidal illness and recovery in dogs

• DOI: 10.1111/jvim.17059
• Publication Date: 2024-04-24T04:39:35Z
• Authors: Andrea Corsini; Francesca Del Baldo; Francesco Lunetta; Serena Ribichini; Massimo Giunti; Francesca Fidanzio; Federico Fracassi
• Keywords: Male; 0301 basic medicine; diagnosis; Veterinary medicine; 610; Thyrotropin; NTIS; 03 medical and health sciences; Dogs; thyroid‐stimulating hormone; SF600-1100; Animals; Dog Diseases; Prospective Studies; Longitudinal Studies; Settore MVET-04/B - Clinica medica veterinaria; thyroid gland; 600; euthyroid sick syndrome; diagnosi; Thyroxine; Acute Disease; Triiodothyronine; Female; hypothyroidism; SMALL ANIMAL; NTIS; diagnosis; euthyroid sick syndrome; hypothyroidism; thyroid gland; thyroid‐stimulating hormone

AbstractBackgroundAcute illness can result in changes in serum total thyroxine (tT4), total triiodothyronine (tT3), and thyrotropin (TSH) concentrations in euthyroid dogs defined as nonthyroidal illness syndrome, but longitudinal evaluation of these hormones during the recovery phase is lacking.ObjectivesTo longitudinally evaluate serum tT4, tT3, and TSH concentrations during the acute phase and recovery from acute illness in dogs.AnimalsNineteen euthyroid client‐owned dogs hospitalized for acute illness at a veterinary teaching hospital.MethodsProspective longitudinal study. Serum tT4, tT3, and TSH concentrations were measured at the admission (T0), at last day of hospitalization (T1), and during the recovery phase at 3, 7, 14, and 21 days after the discharge (T2, T3, T4, and T5), respectively.ResultstT4 and tT3 were below the reference interval (RI) at T0 in 3 (16%) and 18 (95%) dogs, respectively; tT4 normalized in all dogs early in the recovery phase, while low tT3 persisted at the end of the study in 16 (83%) dogs. Median TSH concentrations were increased at T5 compared with T1 (0.19 ng/mL [range 0.03‐0.65] vs 0.11 ng/mL [range (0.05‐0.26)], mean difference = 0.09 ng/mL; P = .03). Five (26%) dogs had TSH above the RI at least at 1 time point during the recovery phase. None of the dogs had concurrent low tT4 and high TSH during the study.Conclusions and Clinical RelevanceIn euthyroid dogs acute illness can interfere with evaluation of thyroid function up to 21 days during the recovery phase. Thyroid testing should be avoided or postponed in these dogs.