25.1 Biochem: Diagnosis of adrenal disorders Flashcards
What disease affect the adrenal cortex and medulla?
Cortex: Cushings/Addisons
Medulla: Pheochryomacytoma
Where in the adrenal cortex are mineralcorticoids, glucocorticoids and sex steroids produced?
Mineralcorticoids (aldosterone): glomerulosa
Glucocorticoids (cortisol, some androg.): fasiculata
Sex steroids, androg., some cortisol: reticularis
Cortisol is synonymous with….?
Hydrocortisone
What are some steps in the steroid synthesis pathway?
Cholesterol–> pregnenolone–> progesterone (then either aldosterone, cortisol or T/E)
What are 4 actions of glucocorticoids?
Gluconeogenesis
Lipolysis
Mobilisation of AAs
Immunosupression
What can long term increases in cortisol lead to?
Weight gain, wasting, hypertension and hyperglycaemia
What are ACTH dependent and independent causes of hypercortisolism?
Depend: pituitary adenoma (Cushing’s disease), ectopic ACTH syndrome
Indep (Cushing’s syndrome): adrenal adenoma/carcinoma, nodular hyperplasia, administration of glucocorticoids
What is the most common cause of hypercortisolism?
Administration of glucorcorticoids (ACTH-independent)
What is the appearance of a person with Cushing’s?
Moon face, adiposity around torso Hirsutism Hypertension (short stature if pre-puberty) Red striae
How do we investigate Cushings?
Dexamethisone supression test and urine free cortisol
What is a condition where we have too little cortisol? What can occur?
Addisons, if organism is stressed then death etc. can occur.
What are some causes of adrenocortical insufficiency? (3)
Genetic (enzyme or metabolic defect), autoimmune, infectious disease (TB)
What are the electrolyte imbalances that occur in Addisons?
Low Na, high K+
What do we see in people with Addisons disease?
Sometimes thin, gum pigmentation, often vitiligo
What is CAH due to in most cases?
21-hydroxylase deficiency
What are the 3 presentations of CAH in females?
Infant: ambiguous genitalia
Child: premature pubic hair, enlarged clitoris
Adolescence: hirsutism and acne
(due to high DHEA)
What do we see in males with CAH?
Baby, 2-3 weeks: adrenal crisis
Toddler, 2-3 yo: premature sexual development
What is aldosterone regulated by?
K+
RAS
What does aldosterone do?
Increases reabsorption of Na/H2O
Increases excretion of K+ from distal tubule
What is Conn’s syndrome?
Mineralocorticoid excess (tumour that secretes aldosterone=high Na, low K)
