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Hyperthyroidism due to an intrathoracic tumour in a dog with test results suggesting hyperadrenocorticism
Author(s) -
Stassen Q. E. M.,
Voorhout G.,
Teske E.,
Rijnberk A.
Publication year - 2007
Publication title -
journal of small animal practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.7
H-Index - 67
eISSN - 1748-5827
pISSN - 0022-4510
DOI - 10.1111/j.1748-5827.2006.00233.x
Subject(s) - medicine , dexamethasone , endocrinology , creatinine , thyroid , dexamethasone suppression test , polyuria , excretion , scintigraphy , diabetes mellitus
The elevated urinary corticoid/creatinine ratios of an 11‐year‐old Jack Russell terrier with polyuria were suppressible in a high‐dose dexamethasone suppression test, which was suggestive of pituitary‐dependent hyperadrenocorticism. The absence of physical and routine‐laboratory changes compatible with hyperadrenocorticism and the relatively high plasma thyroxine concentration were the impetus for additional studies of thyroid and adrenocortical functions. A high plasma thyroxine concentration (62 nmol/l; 5·0 μg/100 ml) suggested the presence of hyperthyroidism. Radiography, 99m TcO 4 − scintigraphy, ultrasonography, computed tomography and cytology revealed a hyperfunctioning intrathoracic thyroid tumour. In the low‐dose dexamethasone suppression test, the plasma cortisol concentration exceeded the reference value of 40 nmol/l (1·4 μg/100 ml) at eight hours after dexamethasone administration (0·01 mg/kg intravenously), a test result compatible with hyperadrenocorticism. In conclusion, this report represents the first case of a dog with an autonomously hyperfunctioning thyroid tumour in the thorax. The elevated urinary corticoid excretion and the positive low‐dose dexamethasone suppression test may be explained by alterations in cortisol metabolism, the stress of the hyperthyroid state or both.