Chapter 23 - Parathyroid Flashcards

1
Q

Superior parathyroids derived from what?

A

4th pharyngeal pouch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Inferior parathyroids derived from what?

A

3rd pharyngeal pouch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Relation of superior parathyroids to surrounding structures?

A

Lateral to RLNs, posterior surface of superior portion of thyroid, above inferior thyroid artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Relation of inferior parathyroids to surrounding structures?

A

Medial to RLNs, more anterior, below inferior thyroid artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Most common ectopic location of inferior parathyroids?

A

Tail of the thymus; can migrate to the anterior mediastinum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Other ectopic sites of parathyroids?

A

Intrathyroid, mediastinal, near TE groove

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What % of patients have all 4 glands?

A

90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Blood supply to both superior and inferior parathyroids?

A

Inferior thyroid artery from thyrocervical trunk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Effects of PTH?

A

Increase serum Ca; increase kidney Ca reabsorpiton in distal convoluted tubule, decrease kidney PO4 absorption, increase osteoclasts in bone to release Ca and PO4, increase Vit D production in kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does vitamin D increase Ca?

A

Increases intestinal Ca and PO4 absorption by increasing Ca-binding protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Effects of calcitonin?

A

Decrease serum Ca; decrease bone Ca resorption (osteoclast inhibition), increase urinary Ca and PO4 excretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Normal PTH level?

A

5-40 pg/mL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Most common cause of hypoparathyroidism?

A

Previous thyroid surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What oncogene increases the risk for parathyroid adenomas?

A

PRAD-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What causes primary hyperparathyroidism?

A

Autonomously high PTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is the diagnosis of primary hyperparathyroidism made?

A

Increased Ca, decreased phos; Cl- to phos ratio >33, increased renal cAMP, HCO3- secreted in urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Acid-base disorder seen with primary hyperparathyroidism?

A

Hyperchloremic metabolic acidosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the bone lesion characteristic of primary hyperparathyroidism?

A

Osteitis fibrosa cystica (brown tumors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Symptoms of primary hyperparathyroidism?

A

Muscle weakness, myalgia, nephrolithiasis, pancreatitis, PUD, depression, bone pain pathologic fractures, mental status changes, constipation, nausea and vomiting, anorexia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Indications for surgery for primary hyperparathyroidism?

A

Ca >13, decreased Cr clearance, kidney stones, substantially decreased bone mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

% of patients with single adenoma?

A

80%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

% of patients with multiple adenomas?

A

4%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

% of patients with diffuse hyperplasia?

A

15%; pts with MEN I or IIa have 4-gland hyperplasia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Treatment for parathyroid adenoma?

A

Resection; inspect other glands to r/o hyperplasia or multiple adenomas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Treatment for parathyroid hyperplasia?
Do not biopsy all glands (risk hemorrhage); resect 3.5 glands or total parathyroidecomy and autoimplantation
26
Treatment for parathyroid adenocarcinoma?
Radical parathyroidectomy (with ipsilateral thyroid)
27
Ideal time for operation in pregnant patient?
2nd trimester; increased risk of stillbirth if not resected
28
Why draw intra-op PTH levels?
Helps determine if causative gland is removed; PTH should go to <1/2 the preop value
29
What is the half-life of PTH?
3-4 minutes
30
What is the most common location of a gland that was unable to be found on initial operation?
Normal anatomic position
31
What is postop hypocalcemia caused by following parathyroidectomy?
Bone hunger, hypomagnesemia, failure of parathyroid remnant or graf
32
What is the most common cause of persistent hyperparathyroidism?
1%; due to missed adenoma
33
What causes recurrent hyperparathyroidsim?
New adenoma formation, tumor implants that have grown, recurrent parathyroid carcinoma
34
Bone hunger will show what lab values?
Normal PTH, decreased HCO3-
35
Aparathyroidism will show what lab values?
Decreased PTH, normal HCO3-
36
What is sestamibi-technetium-99 good for?
Preferential uptake by overactive parathyroid gland; good for picking up adenomas (not for hyperplasia); best for trying to pick up ectopic glands
37
What patients show secondary hyperparathyroidism?
Renal failure
38
Lab values in secondary hyperparathyroidism?
Increased PTH in response to decreased Ca
39
Treatment for secondary hyperparathyroidism?
Control diet PO4, PO4-binding gel, decreased aluminum, Ca supplement, vitamin D/Ca in dialysate
40
When is surgery indicated for secondary hyperparathyroidism?
Bone pain (80-90% get relief); total parathyroidecomy with autotransplantation
41
What is tertiary hyperparathyroidism?
Renal disease has been corrected with transplant, but still oerproduces PTH
42
Treatment of tertiary hyperparathyroidism?
Subtotal or total parathyroidectomy with autoimplantation
43
Lab values seen in familial hypercalcemic hypocalciuria?
High serum Ca, low urin Ca (should be high if hyperparathyroidism)
44
What is the cause of familial hypercalcemic hypocalciuria?
Defect in PTH receptor in distal convoluted tubule of kidney; causes increased resorption of Ca
45
Treatment for familial hypercalcemia hypocalciuria?
Nothing. Ca generally not that high; NO parathyroidectomy
46
What is pseudohypoparathyroidism caused be?
Defect in PTH receptor in kidney, does not respond to PTH
47
5-year survival for parathyroid cancer?
50% 5 year survival
48
Lab values in parathyroid cancer?
High Ca, PTH, and alkaline phosphatase
49
Most common site of mets from parathyroid cancer?
Lung
50
% of patients with parathyroid cancer recurrence?
50%
51
What are the tumors of MEN syndromes derived from?
APUD cells
52
Inheritance of MEN syndromes?
Autosomal dominant, 100% penetrance, variable expressivity
53
Tumors associated with MEN I?
Parathyroid hyperplasia (usually 1st to become symptomatic), pancreatic islet cell tumors, pituitary adenoma; correct hyperparathyroidism 1st
54
Tumors associated with MEN IIa?
Parathyroid hyperplasia, pheochromocytoma, medullary cancer of thyroid; correct pheo first
55
#1 cause of death in MEN IIa/IIb?
Medullary thyroid cancer
56
Tumors associated with MEN IIb?
Pheochromocytoma, medullary cancer of thyroid, mucosal neuromas, Marfan's habitus, musculoskeletal abnormalities
57
Gene mutation associated with MEN I?
MENIN gene
58
Gene mutation associated with MEN II?
RET proto-oncogene
59
Other causes of hypercalcemia?
Malignancy, hyperthyroidism, immobilization, granulomatous disease, excess vitamin D, milk-alkali syndrome, thiazide diuretics
60
MOA of midramycin?
Inhibits osteoclasts (used with malignancies or failure of conventional treatment); has hematologic, liver, renal side effects
61
What causes a hypercalcemic crisis? Treatment?
Usually secondary to another surgery; furosemide, dialysis