Endocrinology Flashcards
Treatment for subacute thyroiditis (de Quervain thyroiditis)
- Beta-blockers: control of thyrotoxic symptoms
- NSAIDs: pain relief
*Glucocorticoids for severe thyroid pain not responding to NSAIDs
Most accurate markers indicating resolution of diabetic ketoacidosis
- Serum anion gap
- Serum beta-hydroxybutyrate levels (not acetoacetate)
Best initial test to Dx acromegaly
Insulin-like growth factor-1 (IGF-1)→significantly ↑↑ level compared to the average for age-matched equivalents►positive screen
Confirmatory test for acromegaly
Measure GH after 100 g of glucose is given orally
- Positive if GH remains high (>5 ng/mL)
- Normally a glucose load completely suppresses levels of GH
Why don’t you have hyperkalemia and salt loss in secondary adrenal insufficiency caused by pituitary disease?
Aldosterone production is mainly dependent on the renin-angiotensin system not from ACTH
*Salt wasting, hyperkalemia, and death are associated with aldosterone deficiency
Use of Metyrapone test. How does it work?
- Assess ACTH production
- Block cortisol production→↑ACTH levels
*A failure of ACTH levels to rise→suggests pituitary insufficiency
Most common cause of panhypopituitarism
Pituitary adenomas
Most common presentation of glucagonoma
- Glucose intolerance
- Necrolytic migratory erythema→annular erythematous dermatitis, blistering and erosions
- Weight loss
- Normocytic normochromic anemia
- Diarrhea, thromboembolism
What is the differential diagnosis in a patient with polydipsia and polyuria? Initial steps in management.
- Diabetes insipidus, psychogenic polydipsia, Diabetes mellitus
- 1st step to evaluate→measure urine osmolarity
- 2nd step→Water deprivation test
Most sensitive test to diagnose pheochromocytoma
Plasma free fractionated metanephrines
Specific findings at the physical exam of Graves disease
- Ophthalmopathy-exophthalmos (proptosis)
- Periorbital edema
- Pretibial myxedema
How are the potassium deposits in DKA and why?
Excess of glucagon→hyperglycemia, ketonemia, osmotic diuresis►net renal loss of K+→depletion of total body K+ stores
*Despite reduction in K+ stores→serum [K+] may be ↑ due to acidemia and ↓insulin activity►redistribution of K+ to the extracellular fluid compartment
Which androgen can be used as a diagnostic marker of androgen-producing adrenal tumors?
Dehydroepiandrosterone sulfate (DHEAS)
*produced predominantly in the adrenal glands that
How do you differentiate hyperthyroidism due to thyroiditis and exogenous thyroid hormone use (factitious thyrotoxicosis)? What do they have in common?
- Common→Radioactive iodine uptake (RAIU) decreased
- Differentiate:
- ↑Thyroglobulin→thyroiditis (subacute or silent), iodide exposure
- ↓Thyroglobulin→Factitious thyrotoxicosis
Why are the thyroid antibodies (antithyroid peroxidase/antithyroglobulin) important to evaluate hypothyroidism?
If TSH is less than double the normal and antibodies are positive→replace thyroid hormone
How can you suspect Hypoparathyroidism induced by low magnesium?
- Low Calcium
- Low Phosphorus (different from other causes of hypoparathyroidism➡High Phosphorus)
Mechanism by which hypomagnesemia induce hypocalcemia
↓Mg→⬆resistance to PTH and ⬇PTH secretion
What potassium level do you expect in a hyperglycemic crisis (DKA or HHS)? Why?
- Normal or slightly elevated serum potassium
- Insulin deficiency→put K+ out of cells
- Osmotic diuresis→excessive urinary K+ loss
*Total body potassium deficit (3-5 mg/kg)
Which is the implication of a total body potassium loss in a Hyperglycemic Hyperosmolar State?
Insulin therapy→abruptly decrease K+ - severe hypokalemia
*K+ reposition during initial insulin therapy
Most likely secondary cause of bone loss when presented with ⬆creatinine, anemia and hypercalcemia?
Multiple myeloma
*⬆Total protein might be found
Cause of Osteitis fibrosa cystica and clinical presentation
- Primary Hyperparathyroidism➡⬆Resorption in cortical bone with subperiosteal thinning and cystic degeneration▶hypercalcemia (constipation, fatigue, etc)
- Secondary hyperparathyroidism➡chronic renal failure
*X-ray: lytic lesions with multifocal involvement
Clinical presentation of myopathy in Cushing syndrome
- Painless progressive proximal muscle weakness, atrophy, no tenderness (may interfere with daily activities)
- Lower extremity more involved
- ESR and CK normal
Cause of myopathy in Cushing syndrome
Glucocorticoid-induced myopathy: Direct catabolic effects of cortisol on skeletal muscle➡muscle atrophy
Common findings of chronic primary adrenal insufficiency
- Hyponatremia: hypovolemia-induced antidiuretic hormone secretion
- Hypoglycemia: cortisol deficiency
- Peripheral eosinophilia: normally inhibited by corticosteroids
*History of weakness, fatigue, anorexia, weight loss
Markers of Nonclassic congenital adrenal hyperplasia
- Hyperandrogenism
- ⬆ 17-hydroxyprogesterone
*Cause by partial ⬇ 21-hydroxylase activity
How do you differentiate central vs nephrogenic diabetes insipidus?
Vasopressin stimulation test
- Central➡⬇urine volume, ⬆urine osmolality
- Nephrogenic➡no effect on urine volume or osmolality
Treatment for hyperprolactinemia
- Dopamine agonists: Cabergoline>Bromocriptine
- Transsphenoidal surgery when not responding to medications
- Radiation (rarely needed)
- Asymptomatic does not need treatment
What is the Kallman syndrome and which is the etiology?
Defective migration of neurons and failure of olfactory bulbs to develop➡⬇GnRH➡⬇FSH, LH, testosterone▶hyposmia/anosmia, Infertility, 50% Renal agenesis
*Failure to complete puberty; a form of hypogonadotropic hypogonadism
Best initial test for GH deficiency
Injecting GHRH➡normal response is ⬆GH
Treatment options for acromegaly
- Surgery: transsphenoidal resection (responds in 70% of cases)
- Medications:
- Cabergoline: Dopamine agonist➡❌GH release
- Octreotide or lanreotide: Somatostatin agonist➡❌GH release
- Pegvisomant: GH receptor antagonist➡❌IGF release from the liver
- Radiotherapy: for no response to surgery or medications
What is Euthyroid sick syndrome?
⬇T3,⬆reverse T3 (rT3), ⬇T4, TSH does not rise
*Clinically euthyroid patients with nonthyroidal systemic illness have low serum levels of thyroid hormones
Most common cause of hypercalcemia
Primary hyperparathyroidism and cancer 90% of cases
First-line treatment for acute hypercalcemia
- Saline hydration at high volume
- Bisphosphonate: Pamidronate, zoledronic acid (take several days to work)
Treatment for acute hypercalcemia when the first option does not work
Calcitonin➡❌Osteoclasts, onset of action is very rapid
Causes of primary hyperparathyroidism
- Solitary adenoma (80%-85%)
- Hyperplasia of all 4 glands (15%-20%)
- Parathyroid malignancy (1%)
Possible clinical presentation of primary hyperparathyroidism
- Asymptomatic
- Acute severe hypercalcemia
- Slower o chronic presentation➡Osteoporosis; Nephrolithiasis and renal insufficiency; muscle weakness, anorexia, nausea, vomiting, abdominal pain; Peptic ulcer disease (calcium ⬆gastrin)
Standard of care for primary hyperparathyroidism and which are the indications?
Surgical removal of involved parathyroid glands
- Bone disease (Ex, Osteoporosis)
- Renal involvement, including stones
- Age <50 yrs
- Calcium consistently 1 point above normal
Most common cause of hypocalcemia. Other causes.
- Primary hypoparathyroidism prior neck surgery (Ex, thyroidectomy)
- Other causes:
- Hypomagnesemia➡Mg is needed to release PTH
- Renal failure➡kidney 25 OH-D▶1,25 OH-D
- Vitamin D deficiency➡inadequate sunlight exposure or insufficient intake; Rickets and Osteomalacia
- Genetic disorders
- Fat malabsorption
- Hypoalbuminemia (no symptoms because free Ca is normal)
Treatment for primary hyperparathyroidism when the first line of management is not possible
Cinacalcet➡❌release of PTH
Most accurate test for Paget disease of bone. Best initial test.
- Radionuclide (technetium) bone scan
- Best initial: Plain film x-rays (lytic and sclerotic lesions, depending on disease stage)
*⬆Alkaline phosphatase; normal GGTP and Bilirrubin aid in diagnosis
Best initial test for hypercortisolism. What other options to rule out it?
- 24-hour urine cortisol (also more specific)
- 1 mg dexamethasone suppression test (sensitive, might be false positive)➡normally suppress morning cortisol level
Best initial test to determine the cause (source) or location of hypercortisolism
ACTH level
Treatment options for endogenous hypercortisolism when surgically removing the source (pituitary, adrenal or cancer) is not possible
- Pasireotide: somatostatin analog➡❌levels and activity of ACTH (for ACTH dependent Cushing sx)
- Mifepristone: ❌cortisol receptors throughout the body
- Mitotane: ❌steroidogenesis, also cytotoxic to adrenal tissue (for adrenal cancer cannot be fully resected or metastatic disease can’t be identified)
Most specific test of adrenal function (mainly for hypoadrenalism)
Cosyntropin (synthetic ACTH) test: measure cortisol before and after administration➡normally ⬆cortisol after giving it
Most common classic presentation of primary hyperaldosteronism
High blood pressure + Hypokalemia
Best initial test for primary hyperaldosteronism
Ratio of plasma aldosterone to plasma renin >20:1
Most accurate test to confirm unilateral adrenal adenoma
Sample of venous blood draining the adrenal➡⬆Aldosterone
Most common cause of primary hyperaldosteronism
- Solitary adenoma
2. Bilateral hyperplasia
Treatment for bilateral adrenal hyperplasia in primary hyperaldosteronism
Eplerenone or Spironolactone
Which treatment for Graves disease may worsen the ophthalmopathy?
Radioactive Iodine➡⬆thyrotropin receptor antibody
*Corticosteroids and antithyroid drugs➡minimize RAI effects
Most common cause of isolated, asymptomatic elevation of alkaline phosphatase in an elderly
Paget disease of bone
Greatest risk of complication if left untreated hyperthyroidism
- ⬆⬆T3, T4➡⬆Osteoclastic bone activity▶⬆bone resorption, ⬇bone density▶osteoporosis
- Also cardiac tachyarrhythmias (AFib)
*⬆Bone turnover➡Hypercalcemia, Hypercalciuria
Best initial and most accurate test for pheochromocytoma
- Best initial: Level of free metanephrines in plasma
- Most accurate: 24-hour urine collection for metanephrines
How do you look for a pheochromocytoma outside the adrenal gland?
Metaiodobenzylguanidine (MIBG) scanning
