Peer-reviewed veterinary case report
Thyroid function tests during nonthyroidal illness syndrome and recovery in acutely ill dogs.
- Journal:
- Journal of veterinary internal medicine
- Year:
- 2024
- Authors:
- Bolton, Timothy A et al.
- Affiliation:
- Department of Small Animal Clinical Sciences · United States
- Species:
- dog
Plain-English summary
In this study, researchers looked at how a condition called nonthyroidal illness syndrome (NTIS) affects thyroid function tests in dogs that are seriously ill. They focused on 25 dogs that were sick but could recover, finding that many had low levels of a thyroid hormone called total thyroxine (TT4) when they were admitted. The researchers took blood samples at various times during the dogs' treatment and recovery, discovering that while most dogs had low TT4 levels at first, these levels improved significantly by the time they were discharged and continued to normalize over the following weeks. They recommend checking thyroid hormone levels again two to four weeks after a dog is discharged to get a clear picture of their thyroid health. Overall, the treatment for the dogs was effective, and their thyroid function returned to normal as they recovered.
Abstract
BACKGROUND: Nonthyroidal illness syndrome (NTIS) can result in thyroid function test alterations that mimic hypothyroidism. The duration of NTIS-induced changes in dogs is not well-described. OBJECTIVES: Document alterations in thyroid function tests during NTIS and recovery, and the time necessary for their resolution. ANIMALS: From 103 dogs sampled, 25 euthyroid dogs with acute, resolvable illness having a low serum total thyroxine (TT4) concentration on admission were analyzed. METHODS: Prospective observational study. Serum TT4 concentration was measured in 103 dogs within 4 hours of admission. If below the reference interval (RI), subsequent serum samples were obtained every 24 hours from admission until discharge (acute phase) and at 2 weeks and 4 weeks after discharge (recovery phase). Serum samples were submitted for batch measurement of serum TT4, free thyroxine (fT4), total 3,5,3'-triiodothyronine (TT3), and thyroid-stimulating hormone (TSH) concentrations. RESULTS: In the cohort of dogs analyzed, serum TT4, TT3, and fT4 concentrations were below the RI in 100%, 80%, and 16% at admission; 20%, 80%, and 0% at discharge; 4%, 8%, and 0% at 2 weeks; and 0%, 0%, and 0% at 4 weeks, respectively. Serum TSH concentration was within the RI in 100% at admission and discharge, and above the RI in 4% and 12% at 2 weeks and 4 weeks, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Naturally occurring NTIS in dogs induces alterations in thyroid function tests during acute illness and recovery. Measurement of serum TT4 concentration 2 to 4 weeks after discharge or serum fT4 concentration by ED during illness is recommended for accurate assessment of thyroid function in acutely ill dogs.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/38032018/