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Surgery > Parathyroid > Flashcards

Parathyroid Flashcards

1
Q

What is the embryologic origin of the parathyroid glands?

A

Superior glands develop from the fourth pharyngeal pouch, while inferior glands develop from the third pharyngeal pouch

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2
Q

What is the average size of a parathyroid gland?

A

<50 mg and 3x3x3 mm

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3
Q

What is the histologic appearance of a normal parathyroid gland?

A

Mainly chief cells, with occasional oxyphils

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4
Q

Describe the vascular supply of the parathyroid glands?

A

Afferent supply from the inferior thyroid arteries; efferent drainage to the superior, middle, and inferior thyroid veins.

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5
Q

To what does active, ionized serum calcium bind to under normal circumstances?

A

80% bound to albumin. 20% found in a citrate complex

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6
Q

What is the primary function of the parathyroid gland

A

To regulate calcium and phosphate in conjunction with vitamin D and calcitonin

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7
Q

What are the effects of PTH on bone?

A
  1. Stimulate osteoclasts
  2. Inhibit osteoblasts
  3. Stimulates bone resorption, releasing calcium and phosphate
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8
Q

What are the effects of PTH on the kidney?

A
  1. Increases reabsorption of calcium

2. Increases phosphate excretion

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9
Q

What are the effects of PTH on the GI tract?

A

Stimulates hydroxylation of 25-OH D

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10
Q

Define hypercalcemic crisis and its treatment.

A

Serum calcium >13 mg/dL and symptomatic. Treat with saline, diuretics, and if needed anti-arrhythmic medication

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11
Q

What is the role of Vit D as it relates to PTH?

A

Increased 1,25 OH D increases absorption of calcium and phosphate, promotes mineralization, and enhances PTH’s effect on bone

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12
Q

What is the role of calcitonin?

A

Inhibits bone resorption, increases urinary excretion of calcium and phosphate.

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13
Q

What cells produce calcitonin?

A

C-cells of the thyroid

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14
Q

What are the biochemical effects of hyperparathyroidism?

A
  1. Increased absorption of calcium from the intestines
  2. Increase vitamin D3 production
  3. Decreased renal calcium excretion

All three raise serum calcium levels

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15
Q

What are the signs and symptoms of hyperparathyroidism?

A

Kidney stones, bone pain, pathologic fractures, nausea, vomiting, constipation, pancreatitis, peptic ulcer disease, lethary, confusion, depression, paranoia

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16
Q

What are the common etiologies of hyperparathyroidism?

A
  1. 85-90% are solitary adenomas
  2. 10% are four-gland hyperplasia
  3. <1% are cancers
17
Q

What are the pre-operative tests for localizing the cause of hyperparathyroidism?

A

US, FNA of suspicious US findings, Sestamibi scan

18
Q

What are the serum lab values typical of hyperparathyroidism?

A

elevated plasma PTH, with inappropriately high serum calcium

19
Q

What is the treatment for solitary adenomas causing hyperparathyroidism?

A

Solitary parathyroidectomy

20
Q

What is the treatment of multiple gland hyperplasia causing hyperparathyroidism?

A

Remove 3 glands, or all four glands with reimplantation of one gland in the forearm.

21
Q

What is the most common cause of hypercalcemia in the outpatient population? What about the inpatient population?

A

Outpatient: Hyperparathyroidism
Inpatient: Hypercalcemia of malignancy

22
Q

What is the success rate of surgical correction for hyperparathyroidism?

A

98% cure from first operative procedure.

90% cure from second procedure of remaining gland is well localized per-operatively

23
Q

What are common causes of secondary hyperparathyroidism?

A
  1. Chronic renal failure

2. Intestinal malabsorption

24
Q

What is the treatment for patients with hyperparathyroidism as part of MEN syndrome?

A

Because of the high rate of recurrence, these patients require total parathyroidectomy with forearm reimplantation to facilitate potential reoperations.

25
Q

What are some of the signs and symptoms of secondary hyperparathyroidism?

A

Patients are often asymptomatic.

May present as bone pain from renal osteodystrophy and pruritus

26
Q

What are the treatments for hyperparathyroidism caused by chronic renal failure?

A

Nonsurgical: restrict phosphorus intake, give phosphorus-binding agents and calcium/vitamin D supplementation, adjust dialysate to maximize calcium and minimize aluminum. Surgical treatment is indicated for intractable bone pain or pruritus, or pathologic fractures in patients who have failed medical therapy.

27
Q

What is the surgical procedure of choice in patients with secondary hyperparathyroidism?

A

3.5 gland parathyroidectomy

28
Q

What is the cause of tertiary hyperparathyroidism?

A

Caused by autonomously functioning parathyroid glands, resistant to negative feedback, generally in the case of prolonged secondary hyperparathyroidism, which does not resolve once the primary cause has been address (for example, persistent hypercalcemia following renal transplantation)

29
Q

What is the treatment for tertiary hyperparathyroidism?

A

Generally, it is a short lived phenomenon. If persistent, surgical excision with 3.5 gland parathyroidectomy is indicated.

30
Q

What are the common etiology of hypoparathyroidism?

A
  1. Iatrogenic 2/2 surgery - usually following total thyroidectomy; often transient and only treated if symptomatic
  2. Congenital absence of all four parathyroid glands
  3. DiGeorge Syndrome: Absence of parathyroids along with thymic agenesis
  4. Functional: chronic hypomagnesemia
31
Q

What are the signs and symptoms of hypoparathyroidism?

A
  1. Numbness and tingling of circumoral area, fingers, and toes
  2. Anxiety and confusion
  3. Late manifestations include tetany, hyperventilation, seizures, and heart block
32
Q

What is the treatment of hypoparathyroidism?

A

Supplementation with calcium and vitamin D

33
Q

What is pseudohypoparathyroidism, and how do you treat it?

A

An inherited disorder in which target tissues are resistant to PTH effects. Patients remain hypocalcemic and hyperphosphatemic despite bone resorption from elevated PTH. Treatment consists of calcium and vitamin D supplementation.

34
Q

What is Chvostek’s sign, and what causes it?

A

Contraction of facial muscles when tapping on facial nerve. Caused by hypocalcemia

35
Q

What is Trousseau’s sign, and what causes it?

A

Development of capal spasms by occluding blood flow to the forearm. Caused by hypocalcemia.

36
Q

What are the signs and symptoms of parathyroid cancer?

A
  1. 40-50% present with firm, fixed mass.
  2. Extremely high calcium, PTH, and alkaline phosphatase
  3. Associated bone disease, renal insufficiency, and renal stones
37
Q

What are the gross and microscopic findings of parathyroid cancer?

A

Pale, while, adherent mass with a thick fibrous capsule and septations. Enlarged hyperchromatic nuclei and varied nuclear size.

38
Q

What is the treatment for parathyroid cancer?

A
  1. En bloc surgical resection of the mass and surrounding structures, ipsilateral thyroid lobectomy, and regional lymph node dissection.
  2. Postoperative radiation therapy and chemotherapy are NOT typically indicated
39
Q

What is the five year survival of parathyroid cancer?

A

70%

Surgery (9 decks)

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