Endocrine

Question 1

Things that unmask occult pheochromocytomas?

Answer 1

Catecholamine surges can happen as a result of:

• Increased intra-abdominal pressure (eg tumor palpation, position changes)
• Sx procedures
• Medications, especially anesthetic agents
• Non-selective beta blockers that lead to unopposed alpha stimulation (need alpha blockers like phenoxybenzamine prior to beta-blockers in patients with pheos)

Question 2

How to calculate number needed to treat (NNT)?

Answer 2

NNT = 1/ARR 
ARR  = absolute risk reduction, difference between placebo and treated group

Question 3

Radioactive iodine treatment

Answer 3

Diffuse uptake of RAI in graves can lead to hypothyroidism in 6-18 weeks in > 90% patients. Can also acutely worsen Graves ophthalmopathy due to increased titers of thyroid-stimulating Abs.

When used to treat toxic nodular goiter and toxic adenoma uptake only by autonomous tissue and function of remaining normal tissue is adequate to prevent hypothyroidism.

Question 4

Glucagonoma

Answer 4

Weight loss
Necrolytic migratory erythema: erythematous papules that coalesce to form large induraged plaques with central clearing
GI sx: diarrhea, anorexia, abd pain

Dx: markedly elevated glucagon levels; MRI abd or CT

Labs show normocytic normochromic anemia, which may be due to ACD or direct effect of glucagon on erythropoiesis