Clin Lab - Adrenal Diagnostics Flashcards
(92 cards)
1
Q
What does HPA axis stand for?
A
Hypothalamic/Pituitary/Adrenal Axis
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Q
Major Hormones of the HPA Axis
A
- Corticotropin Releasing Hormone (CRH)
- Adrenocorticotropic Hormone (ACTH)
- Adrenal Cortex Hormones
–> Cortisol
–> Aldosterone
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Q
3 main types of cortex hormones
A
- Glucocorticoids
- Mineralocorticoids
- Androgens
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Q
Glucocorticoids function & example
A
Stress response
Ex - Cortisol
anti-inflammatory, gluconeogenesis, decr bone formation
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Q
Mineralocorticoids function & example
A
Water/salt balance, BP
Ex - Aldosterone
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Q
Androgens function
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secondary sex characteristics
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Adrenal Medulla hormones
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epi/norepi
- fight or flight
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Q
Causes of Primary disorder:
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- Adrenal tumor
- Autoimmune
- Genetic/Congenital
- Damage – trauma, surg, radiation
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Q
Causes of 2ndary disorder:
A
- Pituitary adenoma
- ACTH-producing tumor
- Pituitary damage – stroke, radiation, ischemia
- Genetic
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Causes of Tertiary (hypothalamus) disorder:
A
- Hypothalamus damage – stroke, radiation
- Tumor
- Genetic
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Q
Other causes for adrenal cortex issues
A
exogenous steroids
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Q
Exogenous causes
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corticosteroids
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Q
S/Sx of exogenous hypercortisolism - Cushing syndrome
A
high BP & sugar levels
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3 causes of endogenous hypercortisolism - Cushing syndrome
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primary, secondary, & tertiary hypercortisolism
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Describe of primary hyperaldosteronism & cause
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- excess production of cortisol from adrenal gland
- adrenal tumor
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Describe of secondary hyperaldosteronism & cause
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- excess release of ACTH causes incr cortisol release
- pituitary adenoma aka Cushing Dz
OR - ectopic tumor via small cell lung CA
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Describe of tertiary hyperaldosteronism & cause
A
excess release of corticotropin releasing hormone from hypothalamus
- Stress > PCOS, diabetes
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Low dose Dexamethasone Suppression Test
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Hypocortisolism diagnostics
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Describe the cosyntropin stimulation test procedure
- Synthetic ACTH (cosyntropin) administered IV
- Serum cortisol levels drawn at time of injection, 30 min after & 1 hr after injection
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- insufficient elevation of cortisol levels = primary adrenal insufficiency
- sufficient incr in cortisol after injection = secondary /tertiary hypocortisolism
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When is serum ACTH done?
in AM
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Secondary/tertiary causes of hypocortisolism disrupts...
both glucocorticoid & mineralocorticoid hormones
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Findings w/primary causes of hypocortisolism
- Hypoglycemia
- Hyperkalemia
- Hyponatremia
- Elevated BUN
- Hypercalcemia
- NAGMA (low CO2, normal anion gap)
Normal serum CO2 22-26
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Secondary/tertiary causes of hypocortisolism disrupts ...
only glucocorticoid hormones
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Findings w/secondary & tertiary causes of hypocortisolism
hypoglycemia
- don't see electrolyte abnormalities like w/primary adrenal insufficiency
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Initial diagnostic testing to prove cortisol level is low.
Early am serum or salivary total cortisol
- In early am, cortisol level should be highest
- AM cortisol < 3 = low
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Hypothyroidism FU testing Primary vs other causes: if primary causes..
- ACTH will be high
- Adrenal glands will NOT response to synthetic ACTH
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Hypothyroidism FU testing Primary vs other causes: if NOT primary causes..
- ACTH will be low
- Adrenal glands WILL respond to synthetic ACTH
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What are the FU test used to determine primary vs secondary causes of hypocortisolism?
1. Cosyntropin (synthetic ACTH) stimulation test
2. Serum ACTH level
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Describe Cosyntropin stimulation test procedure
- Synthetic ACTH (Cosyntropin) administered IV
- Serum cortisol levels drawn at time of injection, 30 min after & 1 hr after injection
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Interpretation of Cosyntropin stimulation test
- insufficient elevation of cortisol levels = primary adrenal insufficiency
- sufficient increase in cortisol after injection = secondary /tertiary hypocortisolism
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When should a serum ACTH be done?
in AM
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Interpretation of serum ACTH
- Elevated = primary adrenal insufficiency is likely
- Low = secondary/tertiary adrenal insufficiency is likely
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FU diagnostics for hypocortisolism
Used to determine cause
- If primary – image the adrenal glands & test mineralocorticoids - CT
- If secondary – image the pituitary – MRI, CT if we can’t
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Draw out chart for hypocortisolism Labs
DONE
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Describe Congenital adrenal hyperplasia
- inborn metabolic disorders in adrenal hormone biosynthesis
- most common is **deficiency in 21-hydroxylase enzyme**
- leads to hyperplasia of the adrenal glands
- hypocortisolism leads to increase ACTH
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Who is screened for congenital adrenal hyperplasia?
newborns
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Congenital Adrenal Hyperplasia pathophys
most cases are caused by lack of 21-hydroxylase
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What is tested in congenital adrenal hyperplasia?
17-hydroxyprogestesterone levels
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Actions of aldosterone
- acts on nephrons
- increases Na+ reabsorption
--> more K+ excreted
--> raises blood volume & therefore BP
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Hyperaldosteronism is usually what type of issue? Causes?
- usually a primary issue
- adrenal tumor/hyperplasia
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Hyperaldosteronism S/Sx
HTN
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Hyperaldosteronism lab findings
- Hypokalemia
- Hypernatremia
+/- hyperglycemia
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Hyperaldosteronism Diagnostics
Measure serum renin & serum aldosterone level
- morning blood sample; pt seated for 10-15 min
- renin - can measure level or can measure activity
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Primary hyperaldosteronism expected levels
- high aldosterone
- low renin activity
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Hypoaldosteronism is usually what type of issue? Causes?
- usually not an adrenal issue
- usually decr renin leads to decr aldosterone
- kidney dz
- Meds - ACEI/ARBs/DRI,NSAIDS, Heparin
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If it is an adrenal issue = Primary adrenal insufficiency: cause & testing
- autoimmune
- testing: AM cortisol levels, ACTH levels, then cosyntropin test
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Testing for hypoaldosteronism
serum aldosterone & renin activity
- incr renin & decr aldosterone
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Follow up testing for hypoaldosteronism
- anti 21-hydroxylase antibodies (autoimmune cause)
- imaging of adrenal glands - CT
