Many times, adrenal masses are found incidentally on a CT scan. These are known as
an “adrenal incidentalomas.”
Rules to remember:
o If the adrenal mass is either greater than 6 cm in size OR is functional
(regardless of size) → surgical intervention is recommended
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o If an adrenal mass is less than 4 cm AND is non-functional → serial CT scans
are recommended every 4-6 months to assess the size of the adrenal mass to
make sure it is not growing
o How to determine functional status of an adrenal mass? Remember the 3 layers
of the adrenal cortex and the one layer of the adrenal medulla and know what is
produced in each layer to determine if it is functioning or not.
o Adrenal Cortex layers (remember by mnemonic GFR as in glomerular filtration
rate):
Zona Glomerulosa → check to see if aldosterone:renin ratio is elevated
(usually more than 20:1)
Zona Fasciculata → check 24 hour urine cortisol levels and if greater than
100 mg/dl → Cushing problem should be suspected
Zona Reticularis → Check 17 OH steroid (DHEA-S) levels. If elevated,
this layer is functioning.
Adrenal Medulla: Check urine VMA or urine metanephrine levels. If either
of these metabolites are elevated, concern is for pheochromocytoma
Pearl # 4: Systematic approach to workup hypercortisolism
First check 24 hour urine cortisol. If greater than 100 mg/dl, then you either have
Cushing syndrome, Cushing’s disease, or ectopic production of ACTH.
Next step is to check the ACTH level. If the ACTH level is suppressed, then the problem
is Cushing syndrome; CT or MRI of adrenals should be done. If ACTH level is elevated,
the patient has either Cushing’s disease (pituitary problem) or ectopic production of
ACTH (like lung cancer)
To distinguish between Cushing’s disease and ectopic production of ACTH, perform a
high dose (8mg) dexamethasone suppression test.
o If high dose dexamethasone suppresses cortisol, problem is Cushing’s disease.
MRI of the pituitary should be performed. If MRI of the pituitary is negative,
perform inferior petrosal sinus sampling.
o If high dose dexamethasone suppression test fails to suppress cortisol, the
problem is ectopic production of ACTH. Check CT scan of chest to rule out lung
cancer.
Pearl # 5: Must know diabetes mellitus high yield facts
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Type 1 DM → lack of insulin because of destruction of pancreatic beta cells →
associated with antibodies to glutamic acid decarboxylase
Type 2 DM → more common in obese individuals and can occur later in life. Insulin
resistance occurs.
Diagnose of DM is made when patient has two fasting glucose levels greater than or
equal to 126 mg/dl or a random glucose level greater than 200 mg/dl especially in the
context of signs and symptoms like polyuria, polydipsia, or unintentional weight loss.
Goal Hgba1C is less than 7%. Hgba1C is an average glucose in a 3 month period.
Pre-prandial glucose goal in a DM patient is 90-130 mg/dl. 2 hour post-prandial glucose
goal is less than 180 mg/dl.
Monofilament foot testing is the best way to prevent diabetic foot ulcers from occurring.
A common organism that causes diabetic foot ulcers is Staph aureus or beta hemolytic
streptococcus.
Eye exams in DM patients are recommended every 1 to 2 years
o If eye exam reveals hard exudates or microaneurysms → patient has non-
proliferative retinopathy → management is by tighter glucose control
o If eye exam reveals neovascularization or cotton-wool spots → patient has
proliferative retinopathy → treat with photocoagulation
Once again, the folks who write the Internal Medicine licensing exams don’t expect you to
have the depth of knowledge regarding hormone-related conditions, metabolism and diabetes
that an endocrinologist possesses. However, topics such as the ones mentioned in the pearls
above should assist you with the endocrinology section of the med school clerkship shelf and
ABIM board exams.
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