Endocrinology AI Flashcards
(500 cards)
What are the two main forms of canine hyperadrenocorticism?
Pituitary-dependent (PDH) and adrenal-dependent (ADH)
What is the difference between pituitary-dependent and adrenal-dependent hyperadrenocorticism?
PDH is caused by excess ACTH secretion and bilateral adrenal hyperplasia, while ADH is caused by adrenal adenomas or carcinomas independent of pituitary control.
What is the normal function of the adrenal cortex?
The adrenal cortex synthesizes and secretes steroid hormones, including glucocorticoids and mineralocorticoids.
What are the three zones of the adrenal cortex?
Zona glomerulosa, zona fasciculata, zona reticularis
What hormones are produced by the zona glomerulosa?
Mineralocorticoids, such as aldosterone
What hormones are produced by the zona fasciculata and zona reticularis?
Glucocorticoids and sex hormones
What is the role of corticotrophin releasing hormone (CRH)?
CRH is synthesized and released by the paraventricular nuclei in the hypothalamus and travels to the anterior pituitary to stimulate the production of ACTH.
What is the initial hormone produced in the synthesis of glucocorticoids and mineralocorticoids?
Pregnenolone
What is hyperadrenocorticism (HAC)?
HAC is a condition characterized by excessive production of steroid hormones, especially glucocorticoids, from the adrenal cortex.
What are the two forms of spontaneous HAC?
Pituitary-dependent (PDH) and adrenal-dependent (ADH)
What percentage of HAC cases are pituitary-dependent?
80-90%
What causes pituitary-dependent HAC?
Excess ACTH secretion and bilateral adrenal hyperplasia
What are microadenomas and where do they arise from in pituitary-dependent HAC?
Microadenomas are tumors <10mm diameter and arise from the pars distalis (70%) or pars intermedia (30%)
What are macroadenomas and what are their characteristics?
Macroadenomas are tumors >10mm diameter, slow growing, and do not always produce neurological signs.
What is adrenal-dependent HAC caused by?
Adrenal adenomas or carcinomas
What are the two main types of tumors that cause adrenal-dependent HAC?
Adrenal adenomas and adrenal carcinomas
What are the differences between microadenomas and macroadenomas?
Microadenomas are smaller (<10mm diameter) and more common, while macroadenomas are larger (>10mm diameter) and slower-growing.
What is Cushing’s disease?
An alternate name for hyperadrenocorticism (HAC) in reference to the MD who first described the condition in people.
What is iatrogenic HAC?
HAC induced by exogenous prednisolone treatment
What is the role of cholesterol in the synthesis of steroid hormones?
All steroid hormones are derived from cholesterol.
How are steroid hormones transported in the blood?
Steroid hormones are transported in association with proteins such as transcortin due to their lipophilic nature.
Which enzyme is inhibited by Trilostane in the synthesis of steroids?
3 β hydroxysteroid dehydrogenase
What hormone is involved in the regulation of electrolyte balance?
Aldosterone, which is produced by the zona glomerulosa in the adrenal cortex.
What is the main cause of pituitary-dependent HAC?
Excess ACTH secretion and bilateral adrenal hyperplasia