Endocrine Flashcards
What is a significant difference in zoledronic acid and calcitonin in the emergency setting?
Zoledronic acid takes 48 hours to work, so if someone is having symptomatic hypercalcemia refractory to fluids then choose calcitonin
The initial step in evaluating hypercalcemia is what?
PTH
The big differentiation point in hypercalcemia is PTH dependent versus independent.
Dependent causes: hyperparathyroidism
Independent causes:
- Elevated PTHrp: hypercalcemia of malignancy
- Elevated vitamin D 1,25: granulomatous disease, lymphoma
- Elecated vitamin D 25: vitamin D intoxication
- Abnormal protein gap, SPEP: MM
The fasting glucose level that defines DM is _____.
126
Demand for insulin decreases or increases during illness?
Increases
This is why DKA often presents because of URIs or other illnesses.
What kind of insulin do patient’s implantable pumps give?
Implantable pumps give a slow drip of fast acting insulin, just like IV pumps but it’s in the subcutaneous tissue instead.
When insulin is labeled 100-U or 50-U, what does that mean?
It means the number of units per mL, so 100-U has 100 U/mL and 50-U has 50 U/mL.
Fast acting insulin delivered subcutaneously has a half-life of about ________________ hours.
3-4
If someone on an insulin pump is hypoglycemic, then one of two things likely happened: _______________________.
they weren’t eating enough or they overdosed themselves
The point is that pumps just give a basal rate and manual pushes, so hypoglycemia is not likely from pump malfunction. Pump malfunction – such as from infection, dislodgement, running out of insulin, or mechanical issue – will result in hyperglycemia.
What defines HHS?
Hyperglycemia and AMS (not of another etiology) without ketosis or acidosis
Review the ranges of potassium and what to do in DKA?
Less than 3.5: give IV potassium first before insulin (20-30 mEq/hr)
3.5 - 5.5: give IV fluids with potassium while giving insulin (20-30 mEq per liter)
Greater than 5.5: give IV fluids without potassium while giving insulin
In general you should not give bicarb to those with DKA. What are the exceptions?
Shock
Cardiac arrest
What blouses are recommended in DKA and HHS?
20 mL/kg
Why does pregnancy change levothyroxine dose needs?
Estrogen increases the amount of thyroxine-binding globulin (TBG) which decreases the amount of circulating T3 and T4.
Describe the pathophysiology of postpartum thyroiditis.
It is similar to Hashimoto’s thyroiditis. Postpartum thyroiditis presents with a brief hyperthyroid phase (due to the antibody attack and release of thyroxine) followed by a hypothyroid phase. It usually resolves and does not require treatment.
When a woman with hypothyroidism becomes pregnant, what is the management algorithm for her levothyroxine?
Increase her prepregnancy dose by 30% and recheck TSH in 4 weeks
Why is hyperthyroidism often missed in the elderly?
They are more likely to present with “apathetic hyperthyroidism” which presents with fatigue and weight loss. They are also more likely to be on beta blockers which will blunt the tachycardia that you’d normally see in someone with hyperthyroidism.
Keep hyperthyroidism in mind when an elderly patient has new-onset atrial fibrillation, new-onset worsening of heart failure, weight loss, or fatigue.
Under which circumstances should you treat subclinical hypothyroidism (elevated TSH with normal T4)?
- Convincing symptoms of hypothyroidism (unless the person is older than 70 and their TSH is less than 6.9)
- TSH 7 - 9.9: treat if younger than 70 regardless of symptoms
- TSH greater than 10
- Pregnant with history of spontaneous miscarriage
Note: obtain anti-thyroid peroxidase antibodies because if these are elevated it is an indicator that the person is going to progress to over hypothyroidism.
What is the one serious adverse effect of subclinical hypothyroidism?
Recurrent miscarriages
Steroid courses less than _____ weeks do not require tapering to prevent adrenal insufficiency.
3
A patient presents with new-onset hypothyroidism. What medications do you need to assess if they’re taking that could cause hypothyroidism?
Amiodarone
Lithium
What does vanillylmandelic acid test for?
Pheochromocytoma
Note: it is not the preferred screening test, though. The more sensitive test is urinary metanephrines and catecholamines.
What things can cause a falsely positive urinary metanephrines screen?
Things that alter the amount of catecholamines in the serum: TCAs, decongestants, cocaine, and methamphetamine
Review triggers of euglycemic DKA in those taking SGLT2 inhibitors.
- Major illness
- Fasting
- Alcohol abuse
- Discontinuation of insulin
- Intense exercise
Review the workup of galactorrhea.
First, women need to have a breast ultrasound and (if older than 30) a mammogram. If either of those is abnormal then you refer for biopsy.
Second, if the imaging is negative then do a serological workup including TSH and prolactin.
If the serological workup is negative, then you can provide reassurance and follow-up.
Note: also consider medicines and supplements as a cause of galactorrhea, such as antipsychotics.
What test helps differentiate constitutional pubertal delay from familial short stature?
Bone age
Pubertal delay presents with a chronological age greater than the bone age, whereas familial short stature presents with chronological age equal to bone age.
A normal growth velocity (on a chart or by report of maintaining percentile over years) is characteristic of which two causes of short stature?
Constitutional pubertal delay and familial short stature
Disorders of hormones that cause short stature such as hypothyroidism, Kallman syndrome, and CNS masses present with loss of growth velocity.
A patient with ESRD presents with labwork that seems to show primary hyperparathyroidism: elevated calcium, elevated vitamin D, and elevated parathyroid hormone. What is likely happening?
Tertiary hyperparathyroidism
ESRD causes secondary hyperparathyroidism by two ways: the kidneys fail to secrete phosphate and the kidneys fail to generate active vitamin D. Chronic secondary hyperparathyroidism can induce the parathyroid glands to become autonomous and fail to respond to hypercalcemia, called tertiary hyperparathyroidism.
The key to the labwork is that it looks like hyperparathyroidism (elevated PTH, elevated Ca, elevated vitamin D) but the phosphorous is also high!
Under which circumstances should you measure an ACTH level?
ACTH should be measured when you are concerned for Cushing’s syndrome (autonomous, inappropriate ACTH secretion) and there is a positive dexamethasone suppression test.
Strict glycemic control does not lower ________ risk in those with diabetes.
macrovascular
Better control does improve microvascular risks (retinopathy, nephropathy, and neuropathy), but data is inconclusive on if it helps prevent CAD.
The two indications for alendronate are ______________.
T score less than -2.5 or pathologic fracture
The two classes of oral T2DM medications that can cause hypoglycemia are _________________.
sulfonylureas (glyburide, glimepiride, glipizide) and meglinitides (nateglinide and repaglinide)
Paget’s disease presents with what findings and symptoms?
- Bone pain
- Multiple sclerotic lesions
- Increased uptake on bone scan
- Normal serum calcium
- Elevated alkaline phosphatase
- Bowing of legs if they are sclerotic
Which antithyroid medicine works faster?
Propylthiouracil
PTU also decreases the production of T4 and the conversion of T4 to T3.
Which antithyroid medicine can be given to pregnant women?
PTU
PTU for Pregnant women.
Why should you not give methylprednisolone for adrenal crisis?
It has less mineralocorticoid activity. Hydrocortisone is needed.
Sodium artificially goes down _____ for every 100 mg/dl glucose above 100.
1.6 mEq/L
What feature is more suggestive of pheochromocytoma on imaging, irregular shape or increased vascularity?
Increased vascularity
Irregular shape is more typical of adrenal carcinoma.
Which syndrome has a worse prognosis, HHS or DKA?
HHS
What are risk factors associated with HHS?
Elderly status
Functional limitations that prevent oral rehydration
Psychiatric medications
Infection
The two cardinal features of HHS are what?
Hyperglycemia-induced dehydration and AMS
*In the absence of ketoacidosis.
What insulin should you start in DKA or HHS?
Provided K is stable enough to start insulin gtt, generally start 0.14 U/kg/hr (usually about 10 U/hr). If glucose fails to drop by greater than or equal to 10% after one hour then bolus 0.14 U/kg.
What are the five I’s of DKA etiology?
Infection (PNA, UTI, sepsis)
Infarction (CVA)
Ischemic (MI)
Insulin deficit (noncompliance)
Intoxication
What hormone should you test in a person with subacute diarrhea, flushing of skin, and a new murmur?
Urinary 5-hydroxindolacetic acid
Carcinoid syndrome
Review the dosing of D10, D25, and D50 for hypoglycemia.
Remember it always multiplies to equal 50.
D50 = 1 mL/kg (usually a 50 mL in adults) 1 x 50 is 50
D25 = 2 mL/kg (usually a 100 mL in adults) 2 x 25 is 50
D10 = 5 mL/kg (usually a 250 mL bolus in adults) 5 x 10 is 50
Elevated PTH and elevated Ca is indicative of _______________ hyperparathyroidism.
primary
Secondary would be low Ca.
What is the pathophysiology of primary and secondary adrenal insufficiency?
Primary: destruction of the adrenal glands (from autoimmune disease, infection, hemorrhage, or infarction)
Secondary: hypothalamic insufficiency (such as from iatrogenic suppression or CNS disease)
What lab helps distinguish primary from secondary adrenal insufficiency?
Potassium
In primary adrenal insufficiency, aldosterone levels are low and so potassium levels are high. In secondary adrenal insufficiency, aldosterone levels are normal and potassium levels are normal.
Random blood glucose greater than ______ and symptoms of diabetes is diagnostic.
200
For people with severe, symptomatic hypercalcemia, the first line medication (after IV fluids) is _________.
zoledronic acid
Consider this in people with corrected Ca > 12
True or false: calcitonin is a rapid-acting medicatioin.
False
It peaks in 24 hours.
What is the dose of 3% hypertonic saline for severely symptomatic hyponatremia?
100-150 mL over 15 minutes, repeated for a total of 300 mL until symptoms resolve
How much does 100 mL of hypertonic saline (3%) raise the serum sodium?
3 mEq
The hyperpigmentation of Addison’s disease most commonly affects which body regions?
Axillary folds, mucosa, and nipples.
Review the layers of the adrenal gland.
Outer cortex:
- Zona glomerulosa: makes aldosterone
- Zona fasciculata: makes glucocorticoids
- Zona reticularis: makes androgens
Innere cortex:
- Adrenal medulla: makes epinephrine
Which steroid has the least mineralocorticoid properties?
Decadron
Explain the order that you need to give medicines for thyroid storm.
1) Propranolol: prevent cardiac decompensation
2) PTU: block the synthesis of new T3/T4
3) KI (1 hour after PTU): block the release of stored thyroid hormone
4) Dex: prevent adrenal insufficiency
What urinary product will be elevated in carcinoid syndrome?
5-hydroxyindoleacetic acid
What is the pediatric dose of 3% hypertonic saline for severe, symptomatic hyponatremia?
2 mL/kg
Review the causes of hypercalcemia.
Parathyroid-mediated:
- Sporadic hyperparathyroidism
- MEN-associated hyperparathyroidism
- Tertiary hyperparathyroidism
Non-PTH mediated:
- Hypercalcemia of malignancy
- Granulomatous disorders
- Exogenous use (iatrogenic or otherwise)
- Medication side effect (HCTZ, lithium)
Other random stuff:
- Hyperthroidism
- Acromegaly
Which T2DM medication can cause liver failure?
All of the thiazolidinediones
How does octreotide help reverse sulfonylurea toxicity?
Octreotide blocks the endogenous release of insulin
Per the ABEM boards, what is the goal of treating acute hypernatremia?
Correction to 140 in 24 hours
What is Chvostek sign?
Tapping the facial nerve near the ear causes facial muscle spasm
(“Cheek-vostek sign.”)
What are the uses of phentolamine and phenoxybenzamine in pheochromocytoma?
Phentolamine is used for titrating in a crisis. Phenoxybenzamine is for perioperative control.
Why is the sulfonylurea of choice glipizide (not glyburide or glimepiride)?
Lower risk of hypoglycemic events than either of those agents
A high fractional excretion of Na and Uosm>Sosm after rehydration in a hypernatremic patient is diagnostic of what?
Salt poisoning
Hypernatremia is often caused by dehydration. Recall that excretion of Na will be low in those who are dehydrated. DI can cause hypernatremia but will lead to dilute urine, not concentrated.
What is the average fluid deficit in HHS?
8-12 L
In adults with euthyroid goiter, the most common cause is ___________. In children, by contrast, the most common cause is _____________.
nontoxic multinodular goiter; Hashimoto’s (chronic lymphocytic thyroiditis)
In which case of thyroid storm would you not give beta blockers first?
In cases of heart failure
BB can induce hemodynamic collapse in patients with CHF from thyroid storm.
After an overdose of a fast-acting insulin, how long does a patient needed to be observed?
6 hours
What other medical intervention is thought to increase risk of metformin-induced lactic acidosis?
Iodinated contrast
It’s best to have patients hold metformin for two days after receiving contrast
Levothyroxine is the synthetic version of which thyroid hormone?
T4
T3 is triiodothyronine.
