Endocrine pt2

Question 1

What is the treatment for hypoparathyroidism?

Answer 1

• High dose Ca⁺⁺
• Calcitriol
• Vitamin D

Question 2

Low ____ post-operatively can predict hypocalcemia.

Answer 2

PTH

Question 3

Why should most hypothyroid patients be deferred for elective surgeries?

Answer 3

↑ risk of CV complications

Question 4

What cells do pheochromocytoma’s originate from?

Answer 4

Chromaffin cells of the adrenal medula (catecholamine secreting tumor)

paraganglioma is an extra-adrenal pheochromocytoma

Question 5

What is the biochemical pathway for epinephrine development?

Answer 5

Phenylalanine → tyrosine
→ dopa → dopamine → NE → Epi

Question 6

How do pheochromocytomas present?

Answer 6

Signs: HTN, ↑HR
Symptoms: Headaches, sweating, N/V, anxiety, diaphoresis

Question 7

What are our goals for perioperative management of pheochromocytoma?

Answer 7

• Treat HTN (α blockers)
• Volume Expansion (fluids)
• Control arrhythmias (β blockers)

Question 8

When should phenoxybenzamine be initiated prior to pheochromocytoma resection?

Answer 8

1 - 3 weeks preoperatively.

phenoxybenzamine (dibenzyline) = alpha adrenergic antagonist

Question 9

What drug is use for α blockade alongside phenoxybenzamine?

Answer 9

Doxazosin (cardura)

may be as effective as phenoxybenzamine and may reduce intra and postop HoTN

Question 10

What medications should be started first for pheochromocytoma patient? Why?

Answer 10

α blocker before a β blocker

If a βblocker is started first then the unopposed α of the catecholamine can worsen vasoconstriction and precipitate HTN crisis & pulm edema.

Question 11

With anesthetic management of pheochromocytoma, what medications should be avoided?

Answer 11

• Ketamine
• Pancuronium

these stimulate catecholamine release

Question 12

Which VAA’s would be a good choice for pheochromocytoma?

Answer 12

Isoflurane or enflurane

Least cardiac depressant

Question 13

If a pregnant patient is diagnosed with pheochromocytoma, then when should it be resected?

Answer 13

2ⁿᵈ trimester (surgical resection)
1st trimester (initiate medical therapy)

elective section at term, avoid vaginal delivery

Question 14

If a pheochromocytoma is developed or diagnosed late in a pregnancy, what should be done?

Answer 14

Elective c-section as vaginal delivery may precipitate HTN crisis.

Question 15

PTH is secreted in response to ____ Ca⁺⁺.

Answer 15

low

Question 16

What common psychiatric drug will increase PTH secretion and decrease cell sensitivity to Ca⁺⁺?

Answer 16

Lithium

Question 17

What are signs of hypothyroidism?

Answer 17

• decreased metabolic activity
• cold intolerance
• lethargy
• decreased CO
• increased PVR

treatment: levoythyroxine

Question 18

What is myxedema?

Answer 18

Extreme hypothyroidism

• stuper, coma
• hypoventilation
• HoTN
• hypothermia
• hypernatremia

medical emergency, mortality 25-50%

Question 19

Anesthetic management of hypothyroidism consists of what considerations?

Answer 19

• May use ketamine for induction (if cardiac suppressed)
• may require less NMB d/t sk-m weakness
• regional preferred over GA
• PNB dose reduced
• more prone to respiratory depression
• delayed gastric emptying

Question 20

Parathyroid inferior glands are located _____ to the RLN?

Answer 20

ventral (anterior)

Question 21

Parathyroid superior glands are usually ____ to the RLN and at the level of ___?

Answer 21

Parathyroid superior glands are usually dorsal (posterior) to the RLN and at the level of cricoid cartilage

Question 22

The parathyroid is composed primarily of ______ and secretes ____?

Answer 22

The parathyroid is composed primarily of chief cells and secretes PTH

Question 23

What are the functions of PTH?

Answer 23

• increases osteoclast activity releasing calcium from bone
• increase calcium reabsorption in kidney
• increases urinary phosphate excretion
• increases GI absorption of calcium

increases serum calcium

Question 24

What is the function of calcitonin?

Answer 24

• released by C-cells in thyroid
• acts on kidneys and bones to restore calcium (decrease serum calcium)

Question 25

What is the total calcium concentration in the blood? How much of this is bound?

Answer 25

* 10mg/dL * 40% bound to albumin

Question 26

How much of unbound calcium is free ionized calcium?

Answer 26

* 50% of unbound calcium (remaining 60% of total calcium) *ionized calcium is the only form biologically active, important for sk-m contraction, coagulation, NT release, endocrine function*

Question 27

What are signs and symptoms of hyperparathyroidism?

Answer 27

"stones, bones, groans, moans" * Renal stones * skeletal issues * abdominal pain * psychiatric symptoms (fatigue, depression...) * cardiac symptoms

Question 28

Biphosphonates and cincacalcet have what effects on calcium and PTH?

Answer 28

* Biphosphonates: lower calcium but not PTH * Cinacalcet: lower calcium and modestly lowers PTH

Question 29

What is the only cure for hyperparathyroidism?

Answer 29

Surgery: parathyroidectomy * hypercalcemia can lead to organ damage and psychiatric issues * surgery is very effective with low morbidity (99% success)

Question 30

Parathyroid imaging consists of what modalities?

Answer 30

* sestamibi scan (Nuc med) * ultrasound * CT * MRI

Question 31

What anesthetic considerations should be made with hyperparathyroid surgery?

Answer 31

* titrate muscle relaxants * positioning issues (fragile) * avoid hypoventilation (acidosis can increase iCa²⁺) * intraop PTH testing * smooth emergence * evaluate for RLN damage

Question 32

What is characteristic of parathyroid crisis? Treatment?

Answer 32

* Ca²⁺ > 15mg/dL * Requires hydration and diuresis (loop diuretic) * glucocorticoids, calcitonin, dialysis

Question 33

For parathyroidectomy, what is the irvin protocol for intraoperative PTH testing?

Answer 33

* baseline * pre-excision * 5, 10, 20 minute after gland excision *>50% decline in post-excision PTH from baseline indicates successful operation*

Question 34

What is the primary function of the adrenal medulla?

Answer 34

* stores catecholamines * 80% stored as Epi * 20% stored as NorEpi * all derived from tyrosine

Question 35

What endocrine effects do catecholamines have?

Answer 35

* increase glycogenolysis, gluconeogenesis, glucagon secretion * decrease glucose uptake

Question 36

What vasoactive medications are commonly used for intraoperative blood pressure control with pheochromocytoma?

Answer 36

* phentolamine * SNP * NTG * Labetalol