SG 1.2: Cases of Adrenal Disorders

Question 1

what is in the differential for cushing?

Answer 1

1. simple obesity
2. PCOS
3. depression
4. Cushing

Question 2

what is the least useful in diagnosing cushing?

hirsutism, muscle weakness, menstrual irregularity, weight fain, bruising

Answer 2

weight gain

the others are more specific

hirsutism = androgen excess

muscle weakness = Cushing or hypothyroidism

menstrual irregularly = Cushing or PCOS

Question 3

which physical finding has the highest discriminate index posting to Cushing syndrome compared with features seen in patients with simple obesity?

Answer 3

red-purple striae and ecchymosis

HTN, truncal obesity and red plethora are also signs but not as discriminatory

Question 4

normal sodium, low K, normal bicarb, normal chloride, kidney and liver function tests are normal
fasting blood sugar is 160

TG are 432, total cholesterol is 195 and HDL is 44

which labs are concerning? can any of these changes be explained by excess hormones?

what test would you want to do next?

Answer 4

hypokalemia = excess mineralocorticoids = hyperaldosteronism

hyperglycemia = excess glucocorticoids

elevated TG = excess glucocorticoids

elevated WBC = elevated glucocorticoids which detach the neutrophils from the endothelium so neutrophil count increases; also causes leukocytosis too; doesn’t mean they have an infection though

screening tests for Cushing: midnight salivary free cortisol on separate nights or 24 hr urinary free cortisol or overnight 1 mg dexamethasone suppression test

8 am serum cortisol isn’t as helpful for cushing because it could be elevated in general or it’s elevated normally but when you check at midnight and it’s elevated it means a lot more – this test is good for adrenal insufficiency

dont do a CT of adrenal because lots of people have incidentinomas

Question 5

what further test would you order to establish a definitive diagnosis for Cushing?

Answer 5

low dose dexamethasone suppression test

but since all 3 screening tests were positive you probably didn’t really need any more tests

ACTH serum test is premature; not used for diagnosing Cushing

Question 6

what results from a low dose dexamethasone suppression test would indicate Cushing?

Answer 6

give dexamethasone for 2 days and check cortisol levels

if it’s suppressed by 90% by the 2nd day then that’s normal but if it isn’t then they have Cushing’s

Question 7

how do you establish if Cushing is ACTH dependent?

Answer 7

check ACTH

if ACTH is elevated then it’s ACTH dependent

Question 8

when would you do a high dose dexamethasone test for Cushing’s?

Answer 8

to determine where the ACTH is coming from

if cortisol repression is more than 50% then that’s an appropriate response and indicates pituitary ACTH production

if it doesn’t it indicates ectopic ACTH production

Question 9

what does the CRF stimulation test tell you about Cushing?

Answer 9

tells you if the ACTH is rom the pituitary or ectopic

if you give CRF and there’s elevated ACTH it indicates pituitary production

Question 10

once you establish Cushing diagnosis and ACTH dependency, what do you do next?

Answer 10

MRI of pituitary

ACTH dependent Cushing with ACTH production in the pituitary gland so do an MRI to see if there’s a tumor

Question 11

what is the significance of a normal finding of an mRI of the pituitary gland with someone who has ACTH dependent Cushing’s? what is the next best step?

Answer 11

inferior petrosal sinus sampling for ACTH measurement

this confirms ACTH is coming from the pituitary

Question 12

what is the differential diagnosis for HTN in a 67 year old?

Answer 12

1. essential HT
2. renal artery stenosis
3. primary aldosteronism
4. pehochromocytoma
5. hypothyroidism (usually diastolic HTN not systolic but still should consider this)

Question 13

what tests do you order when you suspect aldosteronism?

Answer 13

1. TSH and free T4
2. kidney US and doppler
3. echocardiography
4. plasma or 24 hr urint metanephrines
5. plasma aldosterone and renin activity
6. overnight 1 mg dexamethasone suppression test

5 is for aldosteronism and the others are to rule out stuff in the differential like hypothyroidism, renal artery stenosis, heart defect, pheochromocytoma, or Cushing’s

Question 14

what test would you order to establish definitive diagnosis of primary aldosteronism?

Answer 14

after you see elevated aldosterone and decreased renin levels then you should do a saline infusion test to confirm the diagnosis

2 confirmatory options are:
1. salt loading test with 24 hr urine collection for free aldosterone

2. saline infusion test for 4 hrs to see if aldosterone production can be suppressed

Question 15

if abdominal CT shows hypoechoic nodule in the medial limb of the left adrenal gland and a normal appearing right adrenal gland, what is the next best step?

Answer 15

adrenal venous sampling! just because the have a tumor doesn’t mean it’s causing increased aldosterone

if the patient was under 25 then may refer to the endocrine surgeon for left adrenalectomy but since he’s 67 it could be an adrenal incidentinoma; so even though there’s a tumor doesn’t mean it’s causing the elevated aldosterone

since it’s hypoechoic it means it’s a benign mass so a needle biopsy of the left adrenal mass isn’t necessary

if bilateral primary aldosteronism then you would start an aldosterone receptor blocker

Question 16

what do the results of an adrenal venous sampling tell you?

Answer 16

a ratio of cortisol:aldosterone over 4:1 compared to the “normal” adrenal gland is consistent with unilateral disease

cortisol corrected ratios less than 4:1 are consistent with bilateral adrenal aldosterone excess

Question 17

when you suspect acute severe adrenal insufficiency what interventions should be taken immediately?

Answer 17

take cortisol and ACTH first because you give any hydrocortisone because you want to know the baseline tests

once stabilized do a urinalysis, ECG, blood and urine cultures, CXR, saline infusion, check serum cortisol and ACTH

Question 18

what is the long term treatment once you stabilize someone with an acute primary adrenal insufficiency crisis?

Answer 18

1. glucocorticoid replacement is essential
2. mineralocorticoid replacement is almost always necessary

adrenal androgen replacement has some benefit in women but it’s controversial

patient education is essential

Question 19

what labs do you order to monitor glucocorticoid replacement during chronic medical therapy for a patient with primary adrenal insufficiency?

Answer 19

we dont do any lab tests

base the success on clinical symptom relief

adjust replacement therapy during times of stress like illness or surgery

Question 20

in addition to clinical assessment, which test may be most helpful to guide the appropriate mineralocorticoid replacement?

Answer 20

plasma renin activity

electrolytes are helpful too but renin is the best because depending on if the mineralocorticoid levels are too high or low the renin levels will be low or high, respectively