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Parathyroid/ pituitary Flashcards

1
Q

Where is the superior parathyroid gland located?

A

Found posterior to the recurrent laryngeal nerve (RLN) and superior to the inferior thyroid artery.

If not here then: tracheoesophageal groove

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2
Q

Where is the inferior parathyroid gland located?

A

Anterior to the RLN and below the inferior thyroid artery.

If not here then: thyrothymic ligament

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3
Q

What is the function of parathyroid hormone (PTH)?

A

Absorbs calcium in the kidney, decreases bicarbonate (HCO3) and phosphate (PO4) absorption in the kidney, and increases calcium and phosphate by bone absorption through osteoclast activation. Activates Vit D.

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4
Q

What is the net effect of PTH on calcium and phosphate levels?

A

Net decrease in phosphate and increase in calcium.

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5
Q

What is the role of calcitonin?

A

Made by parafollicular C cells

Causes kidney calcium and phosphate excretion, inhibits calcium and phosphate resorption from bone by osteoclast inhibition.

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6
Q

What is the pathway for vitamin D synthesis?

A

7-dehydrocholesterol –> ingested or UV light –> Vitamin D3 –> liver (25-OH) –> Vitamin D3-25OH –> kidney (1-hydroxylation) –> 1,25-dihydroxycholecalciferol.

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7
Q

What does vitamin D do?

A

Increases intestinal calcium and phosphate absorption by activation of calcium binding protein.

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8
Q

What is the normal range for PTH?

A

10-16 pg/mL.

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9
Q

What cells produce PTH?

A

Made by chief cells in the parathyroid glands.

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10
Q

What triggers the release of PTH?

A

Released in response to low calcium and low vitamin D levels.

So patients with low vitamin D will have high PTH, must correct vitamin D before diagnosis of PHPT

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11
Q

What is the most common cause of primary hyperparathyroidism?

A

A single adenoma (80% of cases).

10-15% caused by hyperplasia, 4% more than 1 adenoma

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12
Q

What is the most common cause of hypercalcemia in the outpatient setting?

A

Primary hyperparathyroidism (PHPT).

Inpatient its cancer

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13
Q

What laboratory findings are associated with hyperparathyroidism?

A

High calcium, high PTH, low phosphate (may not be low if renal failure), Cl:phosphate ratio > 33, high urinary calcium

Labs can be subtle: A high Ca and a high normal PTH is still consistent with PHPT
Cl:phosphate ratio > 33
- PTH increases chloride levels
- Hyperchloremic metabolic acidosis

Increase in urine cAMP – unlike FHH

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14
Q

What is osteitis fibrosa cystica?

A

Bone lesions from calcium resorption, characteristic for primary hyperparathyroidism.

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15
Q

What is the first step in preoperative localization for parathyroid surgery?

A

Get an ultrasound of the neck and localize with a sestamibi scan with SPECT.

-If above did not localize: Next step is CT
-Sestamibi scan – used to find ADENOMAS. Not good for hyperplasia

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16
Q

What are surgical indications for parathyroidectomy?

A

All patients with symptoms: pancreatitis, kidney stones, cholelithiasis, PUD, constipation, depression, bone pain, osteoporosis

Asymptomatic patients with significant lab findings: serum/urinary calcium, creatine clearance, T-score <-2.5 or vertebral fracture

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17
Q

What is the treatment for a single adenoma in hyperparathyroidism?

A

Resect the adenoma.

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18
Q

What is the treatment for 4-gland hyperplasia?

A

Remove all 4 glands and re-implant half of a gland into the brachioradialis muscle.

  • Must re-implant into arm for MEN syndrome!!!!!
  • Other option is to resect 3 ½ and leave ½ in place, avoid this in MEN syndrome, b/c if you need to re-operative = poor tissues
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19
Q

parathyroid intraoperative procedure

A
  • Sit patient with head up (semi-Fowler’s position) (beach chair position), with arms tucked
  • Transverse incision 2 finger breathes above sternal notch
  • Make subplatysmal flap, superior flap to cricoid cartilage, inferior flap to sternal notch.
  • Divide midline raphe of strap mm
  • Dissect between muscles and thyroid (stay close to thyroid to avoid injury to RLN)
  • If adenoma, find the one targeted. Get pre-op PTH, then resect and send for frozen, check PTH immediately after excision, then in 5, 10, AND 20 minutes. Should drop by 50%.
20
Q

What is the Miami criteria for intraoperative PTH monitoring?

A

A 50% drop in PTH compared to preoperative or highest intraoperative value before excision.

-If doesn’t drop need to explore all the other glands

21
Q

What is the most common cause of post-operative persistent hyperparathyroidism?

A

Missed adenoma in the neck. Get sestamibi scan

22
Q

What is the most common cause of secondary hyperparathyroidism?

A

Secondary hyperparathyroidism = hyperplasia
MCC is kidney disease, also caused by Vitamin D deficiency (low 1,25 OH hydroxyvitamin D)
Very High PTH, low-normal Ca, high PO4 (kidney disease)

23
Q

What is calciphylaxis?

A

Calciphylaxis – renal failure and 2ndary hyperparathyroidism.
- Ca-phos deposit in medium sized vessels.
- Sx: skin necrosis. DX: skin biopsy (calcium deposits).
- Tx: Do not debride. Treatment is parathyroidectomy. Can try sodium thiosulfate, cinacalcet
Medical Tx:
- sevelamer chloride (binds phosphate), calcitriol, Ca supplement
- Cinacalcet – increases sensitivity of parathyroid to Ca  decreases PTH, Ca, and phos
Surgical indications:
- Maxed out on cinacalcet/not tolerating, still with high PTH or phos
- PTH > 800
- Intractable symptoms, pruritis, bone pain
- Calciphylaxis
Surgical treatment:
- All need 4 quadrant BL exploration
- Subtotal parathyroidectomy (resect 3 glands) (preferred) but can also do total parathyroidectomy and implant in forearm

Persistently high PTH and phosphorous associated with CV morbidity, fractures, and mortality!!

24
Q

What is the treatment for pseudohypoparathyroidism?

A

Pseudohypoparathyroidism – Kidney insensitivity to PTH
Low Ca, high Phosphate, high PTH
Patients usually short, obese, stubby fingers with dimpling of knuckles with fist
Tx: oral calcium and vit D

25
Q

What defines tertiary hyperparathyroidism?

A

Tertiary hyperparathyroidism = autonomous secretion of PTH even after correction of secondary hyperparathyroidism (e.g. kidney transplant) OR secondary hyperparathyroidism that have hypercalcemia that is refractory to medical management
- High Ca and high PTH, low phos
- Initial management is medical likely 2ndary
- Surgical indications: Refractory to treatment hypercalcemia or basically any symptoms
- Surgery:
- All need 4 quadrant BL exploration
- Subtotal parathyroidectomy (resect 3 glands) (best)

26
Q

What is familial hypocalciuric hypercalcemia?

A

Familial hypocalciuric hypercalcemia – Autosomal dominant
- slightly high PTH and Ca. Low phosphate, high chloride, Low urine Ca (24 urine Ca < 100 = diagnostic)
- Defect in Ca receptor in kidney not detecting Ca, causing increased PTH, which causes increased Ca resorption in kidney
- Defect in CASR gene

27
Q

Bilateral 4 quadrant neck exploration is needed for:

A
  • No 50% drop in PTH intra op  only resect enlarged glands
  • Negative pre-operative localization surgery
  • For all 2ndary and tertiary hyperparathyroidism
  • 4 glands enlarged disease  If MEN I or IIa
  • If 2-3 enlarged parathyroid – excise all of them
28
Q

If can’t find intra-op:

A
  • 1st explore all 4 glands- must do this in MEN syndrome for all
  • Never resect normal glands, never biopsy normal glands
  • If missing inferior gland  check #1 thymus, and then intra-thyroidal
  • If missing superior gland  #1Tracheoesophageal groove, #2 retroesophageal, carotid sheathe, and paraesophageal spaces
  • Never do median sternotomy at initial operation
29
Q

Re-exploration parathyroidectomy

A
  • Higher chance of recurrent laryngeal injury and hypothyroidism
30
Q

Post op hypocalcemia

A
  • Check calcium levels only if symptomatic. Start with oral calcium and vitamin D
  • IV calcium only for severe symptoms: tetany, seizures, prolonged QT, calcium < 7.5
  • Perioral and hand numbness is not severe
  • Bone hunger: Normal PTH and low HCO3, low phosphate and mg
  • Graft/remnant failure – low PTH and normal HCO3
31
Q

Parathyroid CA

A
  • Ca > 14, and PTH > 300
  • en bloc resection, with adjacent thyroid lobe AND central neck dissection, MRND if nodes affected
  • Cinacalcet: treatment of hypercalcemia associated with parathyroid CA
  • MC mets to lung
32
Q

MEN I

A

-Parathyroid hyperplasia 90% chance - 1st to be symptomatic. Need to fix this first
-Pancreatic 40% - Gastrinoma #1 – MCC of mortality
-Pituitary 40% - #1 prolactinoma

33
Q

MEN IIa

A
  • Parathyroid hyperplasia 25%
  • Medullary thyroid cancer 90% - first to be symptomatic: Diarrhea. MCC of mortality
  • Pheochromocytoma 50%- nearly always benign. Treat this first
34
Q

MEN IIb

A

-Medullary thyroid cancer 90% - first to be symptomatic: Diarrhea. MCC of mortality
-Pheochromocytoma 50%- nearly always benign. Treat this first
-Mucosal neuromas, Marfan’s habits, musculoskeletal abnormalities

35
Q

Posterior pituitary

A

ADH – supraoptic nuclei. Osmolar receptors in the hypothalamus (high osmolarity increases release or low volume)

Oxytocin – paraventricular nuclei

36
Q

Anterior pituitary

A

No direct blood supply; from portal venous blood by passing neurohypophysis first
Releases: ACTH, TSH, GH, LH, FSH, prolactin

37
Q

Bi-temporal hemianopia

A

Pituitary mass compressing optic nerve (CN II) at chasm

38
Q

CI to transsphenoidal resection

A

Supracellar extension (dumbbell shaped), massive lateral extension

39
Q

Bromocriptine

A

dopamine agonist; can be used for all endocrine tumors in pituitary except ACTH

40
Q

Prolactinoma

A

MC pituitary tumor. MC microadenoma
Most don’t need surgery

Tx:
-Asymptomatic and Microadenoma < 1 cm: follow MRI
-Symptomatic or macro > 1 cm: Bromocriptine or cabergoline.
-Transphenoidal resection for failed medical tx, hemorrhage, visual loss, wants pregnancy, or CSF leak

41
Q

Acromegaly

A

-Insulin like growth factor – best test. MRI.
MC macroadenoma.
Surgery is 1st line: Transphenoidal resection.
Pegvisomant: GH receptor antagonist

42
Q

Sheehan’s syndrome

A

-Anterior pituitary ischemia 2/2 hemorrhage & hypotensive episode during child birth
-Trouble lactating, amenorrhea, hypothyroidism, adrenal insufficiency
-Tx: corticosteroids, hormone replacement

43
Q

Pituitary apoplexy

A

Bleeding into a pituitary tumor with subsequent destruction of the gland
-Tx: corticosteroids, hormone replacement

44
Q

Craniopharyngioma – Benign. MC children. Treatment is surgery if symptomatic.

A

Craniopharyngioma – Benign. MC children. Treatment is surgery if symptomatic. Diabetes insidious is frequent complication postoperatively.

45
Q

BL pituitary masses

A

MC mets

46
Q

Young patient, primary hyperparathyroidism wiht multigland disease…next best step

A

Genetic testing. Primary hyperparathyroidism is often earlist manifestation of MEN1. Changes opperative approach. MEN1= subtotal parathyroidectomy. MEN2A resect visibly enlarged glands.

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