disorders of the adrenal gland Flashcards
where is the problem located in the hypothalamic-pituitary axis for: primary, secondary, and tertiary disorder
primary = target organ
secondary = pituitary
tertiary = hypothalamus
*more organs involved
what is the predominant feedback loop w/in the endocrine system?
Negative
example of a positive feedback loop?
oxytocin
what types of hormones are produced in the 4 zones of the adrenal gland?
outer = Mineralocorticoids (Aldosterone)
middle = Glucocorticoids (Cortisol)
inner = Adrenal Androgens (DHEA)
medulla = Catecholamines (epi and NE)
aldosterone causes increased reaborptionn of ____ and increased excretion of _____.
Na and water
K+ and H+
aldosterone controls fluid volume**
describe cortisol secretion
it is pulsatile (stress), diurnal (circadian regulation), and under control of ACTH
long term high dose glucocorticoid therapy can cause…?
adrenal atropohy
primary overproduction of cortisol by adrenal glands inhibits _____.
ACTH secretion
what is the role of glucocorticoids (cortisol) in the body?
Protects against hypoglycemia Decrease insulin sensitivity Anti-inflammatory Suppression of immune responses Maintain vascular responsiveness to NE/Epi Inhibits bone formation Promotes increases in GFR
what effect can “weak” androgens have in males/females?
males –> limited physiological significance
females –> major source of androgens (pubic and axillary hair during early development), masculinization
How can you measure catecholamine levels?
urine test bc metabolites are excreted in the urine
what are some physiologic effects of catecholamines?
Increased rate and force of contraction of the heart muscle Constriction of blood vessels Stimulation of lipolysis in fat cells Increased metabolic rate Dilation of the pupils
effects of short-term stress response in the body
increased HR and BP, liver converts glycogen to glucose > releases glucose to blood, incr. metabolic rate
effects of long-term stress response in the body
retention of Na/H2O by kidneys, incr. blood volume and BP, proteins and fats converted to glucose or broken down, increased blood sugar, suppression of immune system
What type of test would assess for hypofunctioning? hyperfunctioning?
hypo = stimulation test
hyper = suppression test
what are adrenal lab tests?
Serum total cortisol 24-hour urinary free cortisol Plasma ACTH ACTH stimulation Dexamethasone suppression
when should you obtain a serum cortisol level?
btwn 8-9am
what lab values would indicate adrenal insufficiency?
serum total cortisol:
< 3 = very likely adrenal insufficiency
btwn 3-10 = inconclusive
> 10 = unlikely adrenal insufficiency
what is the ideal situation for using a 24-hr urinary free cortisol test?
suspected hypercortisolism
where is ACTH produced?
pituitary
what time of day should you measure plasma ACTH?
in the AM
when would you order an ACTH stimulation test?
to differentiate source of adrenal insufficiency (cortisol deficiency)
ACTH stimulation test: if cortisol level doubles where is the problem?
if it is a subnormal response where is the problem?
no problem. adrenal gland is functioning!
adrenal insufficiency
what is the dexamethasone suppression test confirm?
Confirm abnormal excess production
Dexamethasone Suppression Test: what result would indicate excess cortisol production
if cortisol level does not change
if suppressed = normal fx
Cushing’s syndrome?
Collection of signs and symptoms due to prolonged exposure to elevated cortisol
MC overal is excess d/t exogenous use
Cushing’s syndrome d/t endogenous reasons?
MC = Pituitary adenoma
adrenal hyperplasia
Adrenocortical tumor
Neuroendocrine tumor
Ectopic production
clinical manifestations of cushing’s syndrome?
HTN, central obesity (moon face), insulin resistance, purple striae, androgen excess (hirsutism), osteoporosis
what 3 signs would increase your suspicion for cushing’s?
characteristic body changes
HTN
glucose intolerance
what tests would you order to dx cushing’s?
what are results consistent w/ cushing’s?
24-hour urinary free cortisol levels = Elevated
Midnight salivary cortisol level = Elevated on 2 separate nights
Dexamethasone suppression test = No change in cortisol levels
Cortisol and ACTH levels for Adrenal hyperplasia or tumor?
cortisol = High
ACTH = low
*target organ problem! ACTH independent
Cortisol and ACTH levels for ACTH producing tumor – pituitary or ectopic?
cortisol = high
ACTH = high
*ACTH dependent
Management of Cushing’s syndrome?
excluded exogenous cortisol use?
pituitary tumor –> consider MRI
ectopic ACTH secreting tumor –> consider CXR and pelvic U/S
adrenal tumor –> palp mass? CT abd
Tx for exogenous corticosteroids?
taper to lowest therapeutic dose
Tx for pituitary adenoma in cushing’s syndrome
transsphenoidal resection
tx for adrenal hyperplasia in cushing’s syndrome
medical management
tx for adrenal tumor in cushing’s syndrome
adrenalectomy
tx for Ectopic ACTH syndrome in cushing’s syndrome
targeted at source of ectopic production
What medications can you use to tx cushing’s?
adrenolytic agents- mitotane
adrenal enzyme inhibitors- Ketoconazole, metyrapone
what is adrenal insufficiency?
primary, secondary, tertiary
primary -> glucorticoid defiencies
secondary -> insufficient ACTH secretion (long term corticoco’s)
tertiary -> insufficient CRH secretion
causes of primary adrenal insufficiency?
MC in US d/t autoimmune cortical destruction (addison’s dz), TB (worldwide), congenital deficiencies, infx, surg (s/p adrenalectomy)
clinical manifestations of adrenal insufficiency
Insidious onset w/ nonspecific symptoms (weakness, fatigue, anorexia, wt. loss), GI sxs (V/D, abd pain), hypotension, hypoglycemia, salt cravings,
**hyperpigmentation - classic
severe –> extremely low levels of cortisol
diagnostic studies assoc. w/adrenal insufficiency
CMP (hyperkalemia, hypercalcemia, hyponatremia)
eosinophilia
andi-adrenal antibodies
AM plasma cortisol (abn low)
plasma ACTH level
ACTH stimulation test (cortisol does NOT incr)
when do you order a radiographic eval of the adrenals for insufficiency?
if the lab workup reveals autoimmune adrenalitis
CT -> infx or malignancy
when should you order an MRI of the pituitary for adrenal insufficiency?
if secondary adrenal insufficiency points toward hypothalamic or pituitary source
Tx for primary adrenal insufficiency
requires both glucocorticoid (hydrocortisone) & mineralocorticoid (fludrocortisone) replacement
Tx for secondary and tertiary Adrenal insuffiency
only glucocorticoid replacement is necessary
what do you need to do if pt is on meds for adrenal insufficiency and they are going through a period of increased stress?
increase the steroids during the period of stress
Tx for adrenal crisis?
IV steroids Correct electrolyte abnormalities 50% dextrose to correct hypoglycemia Initiate volume resuscitation Search for underlying cause
Primary hyperaldosteronism
aka Conn’s syndrome d/t
adrenocortical adenoma or cortical hyperplasia
presentation of primary hyperaldosteronism
Hypertension Hypokalemia Muscular weakness Paresthesias Headache Polyuria & polydipsia
diagnostic workup for primary hyperaldosteronism
Elevated plasma and urine aldosterone
Low plasma renin levels
Ct scan of adrenals to evaluate for adrenal adenoma
management for primary hyperaldosteronism
Surgical removal of adenoma
Medical = spironolactone and antihypertensive agents
what is Pheochromocytoma
Rare tumor that arises from chromaffin cells that secretes catecholamines
80% to 90% located in adrenal medulla
10% are malignant
clinical manifestations for pheochromocytoma
Paroxysmal Palpitations (tachycardia), Headache and Episodic sweating Paroxysmal or sustained hypertension
less common: pallor, N, tremor, fatigue, anxiety, hypertensive retinopathy
describe a Pheochromocytoma “attack”
Usu. last 30-40 minutes
May be precipitated by displacement of abdominal contents (ie lifting, bending, deep palpation)
when to suspect a pheo?
Classic paroxysmal “attacks,”
refractory HTN or onset <20 y/o, idiopathic dilated cardiomyopathy, abd mass, family hx, incidentally discovered adrenal mass
what is the 1st line screening for dx of pheochromocytoma?
metanephrine (catecholamine metabolite) 24hr urine screen
what other tests can you order to dx pheo?
Clonidine suppression test
MRI of abd/pelvis to locate tumors
MIBG scintigraphy
Tx of pheochromocytoma
surgical resection
prior to surg
- alpha adrenergic blocker until BP and sxs controlled
- BB (propranalol) for tachy
Adrenal Incidentaloma
Mass lesion greater than 1 cm discovered incidentally by radiologic examination
higher prevalence in obese, HTN, and DM pt’s
workup for adrenal incidentaloma
Everyone gets plasma cortisol, serum ACTH, serum DHEA, plasma aldosterone
s/s of cushing’s –>
yes = 24 hr urinary free cortisol
no = 1-mg overnight dexamethasone suppression test
susp. for pheo?
24-hr urine metanephrines, catecholamines
when is FNA/bx indicated for adrenal incidentaloma?
Do it –> known primary malignancy elsewhere
Do NOT –> Biochemical evidence of pheo or known widespread metastatic disease
management of adrenal incidentaloma
documented pheo or carcinoma –> prompt surg.
pharmacologic to tx underlying
benign appearing on imaging:
>2cm –> consider resection
<2cm –> repeat imaging 6mo’s
repeat Dexamethasone suppr. test annually x4yrs
