Ultrasonographic Measurements of Adrenal Glands in Cats With Hyperthyroidism

Abstract

Feline hyperthyroidism is potentially associated with exaggerated responsiveness of the adrenal gland cortex. The adrenal glands of 23 hyperthyroid cats were examined ultrasonographically and compared to the adrenal glands of 30 control cats. Ten hyperthyroid cats had received antithyroid drugs until 2 weeks before sonography, the other 13 were untreated. There was no difference in adrenal gland shape between healthy and hyperthyroid cats: bean-shaped, well-defined, hypoechoic structures surrounded by a hyperechoic halo in 43/60 (71.6%) healthy cats and 34/46 (73.9%) hyperthyroid cats; more ovoid in 13/60 (21.6%) healthy cats and 9/46 (19.6%) hyperthyroid cats while more elongated in 4/60 (6.7%) healthy cats, 3/46 (6.5%) hyperthyroid cats. Hyperechoic foci were present in 9/23 (39.1%) hyperthyroid cats and 2/30 (6.7%) healthy cats. The adrenal glands were significantly larger in hyperthyroid cats, although there was overlap in size range. The mean difference between hyperthyroid cats and healthy cats was 1.6 and 1.7 mm in left and right adrenal gland length, 0.8 and 0.9 mm in left and right cranial adrenal gland height, and 0.4 and 0.9 mm in left and right caudal adrenal gland height. There was no significant difference between the adrenal gland measurements in treated and untreated hyperthyroid cats. The adrenomegaly was most likely associated with the hypersecretion of the adrenal cortex documented in hyperthyroid cats. Hyperthyroidism should be an alternative to hyperadrenocorticism, hyperaldosteronism, and acromegaly in cats with bilateral moderate adrenomegaly.

Feline Hyperthyroidism

“…Other studies have documented mild adrenomegaly in hyperthyroid cats compared with healthy euthyroid cats, and higher UCCR in hyperthyroid cats compared to healthy cats (de Lange et al, 2004;Combes et al, 2012). Taken together, these studies suggest that there is some degree of hypercortisolemia and adrenal gland hyperplasia in hyperthyroid cats.…”

Clinical Findings, Diagnostic Test Results, and Treatment Outcome in Cats with Spontaneous Hyperadrenocorticism: 30 Cases

“…Adrenal gland ultrasonographic descriptions (including adrenal gland width when available and subjective assessment of adrenal size) and abnormalities noted in other intra‐abdominal organs, as well as documentation and description of a pituitary mass on CT or MRI, were recorded only when the study was performed by a board‐certified veterinary radiologist. Normal ultrasonographic adrenal gland width was defined as 3.0–5.9 mm . Treatment modality, resolution of clinical signs, change in insulin dose in response to treatment, and survival time from diagnosis were recorded when available.…”

Feline Acromegaly

“…Bilateral adrenomegaly with adrenal thickness was found in 54% of acromegalic cats (Lourenço et al 2015). Adrenomegaly is not pathognomonic for HS, because it is also found in cats with hyperadrenocorticism, hyperthyroidism and hyperaldosteronism (Combes et al 2012). Adrenomegaly in conjunction with enlargement of other abdominal organs, in particular the kidneys should raise suspicion for HS.…”