Endocrinology Flashcards
What is a Dexamethasone suppression test used to dx? What is a positive result?
It is used to diagnosis hypercortisolism (Cushing’s).
It is positive when a big dose of dexamethasone FAILS to decrease AM cortisol to <3
When do you surgically remove an adrenal ADENOMA?
As in, all the studies show that it is not secreting hormones.
Those at Increased risk of an adrenal malignancy having ALL of the following characteristics;
- size >4 cm
- density ≥10 Hounsfield units
- absolute contrast washout <50% at 10 minutes
What is the most common type of thyroid cancer? What is the biggest risk factor for thyroid cancer?
Papillary Thyroid CA
Radiation exposure during childhood (ex: Hodgkin’s lymphoma)
For treatment of hyperthyroidism, when do you use Methimazole and when do you need to treat with radioactive iodine?
You use radioactive iodine to treat a Toxic Adenoma.
Methimazole treats graves hyperthyroidism.
Methimazole won’t work in a toxic adenoma, because the adenoma just keeps making thyroid hormones indefinitely
How do you manage a pt with Prolactin >200 (normal is <20) in a woman with schizophrenia on Risperdone?
Pituitary MRI, it’s not safe to stop this person’s antipsychotic medication.
Evaluation for pituitary hypersecretion when a patient is taking a medication known to raise the prolactin level is difficult.
If PRL is elevated, but <50, you can assume it’s the meds.
If PRL>100, either the medication needs to be withheld to further assess or a pituitary MRI obtained to evaluate for prolactinoma.
Caution is warranted when discontinuation of an antipsychotic agent is being considered, and consultation with a psychiatrist is recommended prior to discontinuation. If the medication cannot be discontinued, a pituitary MRI is required to exclude the diagnosis of pituitary tumor.
What hypoglycemic agent can increase vulvovaginal candidiasis?
Empagliflozin (SGLT-2 inhibitor)
What factors decrease levothyroxine absorption?
Increase?
Decrease: Celiac Disease, Ca, Iron, PPIs
Increase: Testosterone, Estrogen
Androgens case a reduction in thyroxine-binding globulin, which consequently increases the proportion of metabolically active free thyroxine that is available. Therefore, you may have to reduce levothyroxine when you’re on hormones to prevent iatrogenic thyrotoxicosis.
What changes should you make to levothyroxine level for a woman with hypothyroidism who becomes pregnant?
You will have to increase the dose by 30% to start, then check regularly during pregnancy
What type of thyroid disease?
Pt hospitalized with STEMI s/p Cath:
Laboratory studies obtained at the time of cardiac catheterization:
Thyroid-stimulating hormone (TSH): 0.2 µU/mL (0.5-5)
Thyroxine (T4), total: 6.5 µg/dL (5-12)
Thyroxine (T4), free: 1.0 ng/dL (0.9-2.4)
Triiodothyronine (T3), total: 60 ng/dL (70-195)
Nonthyroidal illness syndrome (euthyroid sick syndrome) is characterized by reduced serum T3, low or low-normal serum T4, and normal or low (but detectable) serum TSH levels.
What is the difference between non thyroidal illness (euthyroid sick syndrome) and subclinical hypothyroidism?
Non thyroidal illness
- critically ill patient
- normal or low (but detectable) serum TSH levels
- reduced serum T3
- low or low-normal serum T4
Subclinical Hypothyroidism: They are hypothyroid based on labs, but not symptomatic.
- Low serum TSH level
- total and free T4 levels are near the lower limit of the normal range
- total T3 is reduced.
Besides IVF, what is the tx for myxedema coma?
IV Hydrocortisone first
Then, Thyroid hormones
In patients with myxedema coma, intravenous hydrocortisone should be administered before thyroid hormones to treat possible adrenal insufficiency.
What is the MCC of primary amenorrhea (never get periods)?
Gonadal Failure (Mullerian agenesis, androgen insensitivity)
This is associated commonly with Turner Syndrome
What is primary ovarian insufficiency?
Primary ovarian insufficiency is considered when a woman younger than 40 years of age develops secondary amenorrhea with two serum FSH levels in the menopausal range (>35 mU/mL [35 U/L]).
Do not confuse this with primary amenorrhea, when a woman never starts periods, which is usually caused by mullein genesis ass’d with Turner syndrome
After ruling out pregnancy, if the cause of secondary amenorrhea is not obvious from the history and physical exam, what is the next step in your evaluation?
FSH, TSH, and prolactin
What is the treatment for PCOS?
- weight reduction
- low dose OCPs (first line) or medroxyprogesterone (↓LH and androgenesis)
- spironolactone (treats acne and hirsutism)
- clomiphene (for women who want to get pregnant)
- metformin (for patients with features of DM or metabolic syndrome)
For someone with features of PCOS, when do you need to get pelvic US?
When testosterone >150 to r/o tumor
Dx of PCOS 2/3 of the following;
- Ovulatory dysfunction (amenorrhea, oligomenorrhea, infertility)
- Lab or clinical evidence of hyperandrogegism (hirsutism, acne)
- US evidence of polycystic ovaries
What is the definition of infertility?
Failure to conceive after 1 year of unprotected intercourse if <35 y/o
Failure to conceive after 6mo if >35 y/o
After making the diagnosis of primary hyperparathyroidism, what other lab must you check before undergoing surgery and why?
25-Hydroxyvitamin D deficiency is important to avoid postoperative hypocalcemia, which occurs due to rapid flux of serum calcium into bone (hungry bone syndrome)
What is the effect of Sarcoidosis on Ca/Phos/Vitamin D/PTH?
1,25-dihydroxyvitamin D is very high
Ca is high
Phos is high
PTH is super low
Macrophages within granulomas convert 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D without regulation by parathyroid hormone. An elevated 1,25-dihydroxyvitamin D level and suppressed parathyroid hormone is diagnostic of vitamin D-dependent hypercalcemia.
As vitamin D enhances absorption of both calcium and phosphorus, concurrent elevation of serum calcium and phosphorus is also suggestive of vitamin D-dependent hypercalcemia.
Derangement of what electrolyte can cause hypocalcemia?
Hypomagnesemia
Hypomagnesemia causes functional, reversible parathyroid hypofunction. So PTH will be wnl, just not working properly and causing low Ca
What is the cause of hypocalcemia after starting zolendronic acid for the treatment of osteoporosis?
Vitamin D Deficiency
This is why it is so important to check Vitamin D levels and correct deficiencies before starting these medications
What test is used to adjust treatment for chronic hypoparathyroidism?
24h urine Ca
You want to raise the Ca, but also avoid the symptoms of hyperCa, mainly kidney stones and renal failure.
Complications of prolonged hypercalciuria include nephrolithiasis and impaired glomerular filtration rate. Serum calcium, magnesium, creatinine, and urine calcium levels should be assessed on a regular basis. The goal calcium levels should be low-normal without hypercalciuria. The magnesium level should ideally be greater than 2 mg/dL (0.83 mmol/L), and creatinine levels should remain in the normal range. If the urine calcium level is greater than 300 mg/24 h (hypercalciuria), calcium and/or vitamin D replacement needs to be decreased
What are the indications for DEXA?
- all women >65 y/o
- <65 if FRAX >8.4% 10y risk
- glucocorticoids
What do the DEXA scores mean?
Osteopenia: T Score -1.0 to -2.4
Osteoporosis: T Score < -2.5
Note: Osteoporosis is also defined by a h/o a fragility fracture
