Peer-reviewed veterinary case report
Thyroid hormone changes in dogs with untreated Addison's disease
By Reusch, C E et al.·Published in Journal of veterinary internal medicine·2017·Clinic for Small Animal Internal Medicine·View original on PubMed →
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Original publication title: Altered Serum Thyrotropin Concentrations in Dogs with Primary Hypoadrenocorticism before and during Treatment.
- Species:
- dog
Plain-English summary
A group of 30 dogs with newly diagnosed Addison's disease (primary hypoadrenocorticism) had their thyroid hormone levels checked to see if they showed signs of thyroid problems. Some of these dogs had increased levels of a hormone called thyrotropin (TSH), which can indicate thyroid issues, but they did not actually have hypothyroidism. After starting treatment with medications like prednisolone, most dogs saw their TSH levels return to normal within a few weeks to a few months without needing additional thyroid medication. This suggests that thyroid function should be carefully evaluated in dogs with Addison's disease to avoid misdiagnosis.
People also search for: dog Addison's disease treatment · dog thyroid problems symptoms · Addison's disease and hypothyroidism in dogs
Abstract
BACKGROUND: Thyrotropin (TSH) can be increased in humans with primary hypoadrenocorticism (HA) before glucocorticoid treatment. Increase in TSH is a typical finding of primary hypothyroidism and both diseases can occur concurrently (Schmidt's syndrome); therefore, care must be taken in assessing thyroid function in untreated human patients with HA. OBJECTIVE: Evaluate whether alterations in cTSH can be observed in dogs with HA in absence of primary hypothyroidism. ANIMALS: Thirty dogs with newly diagnosed HA, and 30 dogs in which HA was suspected but excluded based on a normal ACTH stimulation test (controls) were prospectively enrolled. METHODS: cTSH and T4 concentrations were determined in all dogs and at selected time points during treatment (prednisolone, fludrocortisone, or DOCP) in dogs with HA. RESULTS: cTSH concentrations ranged from 0.01 to 2.6 ng/mL (median 0.29) and were increased in 11/30 dogs with HA; values in controls were all within the reference interval (range: 0.01-0.2 ng/dL; median 0.06). There was no difference in T4 between dogs with increased cTSH (T4 range 1.0-2.1; median 1.3 μg/dL) compared to those with normal cTSH (T4 range 0.5-3.4, median 1.4 μg/dL; P=0.69) and controls (T4 range 0.3-3.8, median 1.8 μg/dL; P=0.35). After starting treatment, cTSH normalized after 2-4 weeks in 9 dogs and after 3 and 4 months in 2 without thyroxine supplementation. CONCLUSIONS AND CLINICAL RELEVANCE: Evaluation of thyroid function in untreated dogs with HA can lead to misdiagnosis of hypothyroidism; treatment with glucocorticoids for up to 4 months can be necessary to normalize cTSH.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/29024024/