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Pathophys II > Parathyroid gland > Flashcards

Parathyroid gland Flashcards

1
Q

Patients have ______ parathyroid glands

A

4

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2
Q

Parathyroid glands produce

A

parathyroid (PTH) also called parathormone)
-released into the bloodstream by negative feedback mechanism
dependent on plasma calcium concentration

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3
Q

The half life of parathyroid hormone levels is________ and the average PTH level is:

A

4 minutes

average PTH level*****: 8-51 pg/mL

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4
Q

Hypocalcemia causes

A

release of parathormone

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5
Q

Hypercalcemia causes

A

suppression of synthesis and release of parathormone

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6
Q

Parathyroid hormone maintains

A

normal plasma calcium concentration*****

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7
Q

Calcium moves across these three interfaces:

A

GI tract, renal tubules, and bone

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8
Q

Calcitonin

A

opposes the effects of PTH

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9
Q

Calcitonin is secreted by

A

the parafollicular cells in the thyroid****

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10
Q

Calcitonin secretion is stimulated by

A

increased serum calcium (hypercalcemia)

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11
Q

Calcitonin lowers

A

blood calcium ***** in 3 ways:
inhibits osteoclast activity in bones (promotes bone storage of calcium)
inhibits renal tubular cell reabsorption of Ca2+
inhibits Ca2+ absorption in the intestines

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12
Q

The osteoclasts are found on the surface of bones and work by

A

breaking down bone tissue by digestion and degradation

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13
Q

Resorption is the

A

absorption into the circulation– osteoclasts break down the bone tissue and release minerals, resulting in the transfer of calcium from bone tissue to the blood

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14
Q

Vitamin D is ______ soluble

A

fat

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15
Q

Vitamin D increases

A

intestinal absorption of calcium, magnesium, and phosphate

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16
Q

Vitamin D maintains

A

calcium homeostasis and metabolism

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17
Q

Vitamin D receptors are found in

A

intestines, kidneys, bone, and parathyroid gland

  • helps transport proteins absorb calcium in the intestine
  • bone resorption
  • Reabsorption of calcium in the distal nephron
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18
Q

Vitamin D can be found from

A

the diet- Vitamin D2 (cholecalciferol) and Vitamin D3 (ergocalciferol)

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19
Q

The synthesis of D2 is dependent on

A

sun exposure

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20
Q

Both Vitamin D2 & D3 get hydrolyzed in

A

the liver to 25-hydroxyvitamin

then in the kidney it gets hydrolyzed again to 1,25-hydroxyvitamin D*****

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21
Q

The normal total (bound and free) serum calcium concentration is

A

9.5-10.5 mg/dL

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22
Q

Normal ionized calcium is

A

****4.75-5.7 mg/dL

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23
Q

Describe how acidosis and alkalosis affect calcium levels.*****

A

acidosis increases serum calcium

alkalosis decreases serum calcium

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24
Q

Approximately _____ of serum calcium is bound to albumin, ______ is ionized, and _____ is bound to chelating agents (phosphate, citrate, and sulfate)

A

50%; 40%; 10%

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25
Q

Ionized calcium fraction depends on

A

pH

26
Q

Protein binding

A

decreases as pH decreases

27
Q

Alkalosis (& calcium)

A

increases calcium binding to protein; decreases ionized fraction

28
Q

Acidosis (& calcium)

A

decreases calcium binding to protein; & increased ionized fraction

29
Q

Each 0.1 decrease in pH increases

A

ionized calcium by 0.05 mmol/L

30
Q

Biological functions of calcium include

A

bone formation, reservoir for ECF, blood clotting, excitability of nerve and muscle, metabolic regulation for action of hormones & enzyme activation

31
Q

Reduced production of PTH can be the result of

A

DiGeorge syndrome
CATCH 22 syndrome
autoimmune

32
Q

Disorders related to PTH include:

A

impaired PTH due to peripheral resistance
parathyroid gland adenomas**
reduced production of PTH

33
Q

Hyperparathyroidism is the

A

excess production of PTH***

34
Q

The most common cause of hyperparathyroidism is

A

hypercalcemia, defined as total serum calcium above 10.4 mg/dL

35
Q

Hyperparathyroidism can be classified as ****

A

primary (parathyroid gland destruction), secondary (appropriate response to hypocalcemia as seen in CKD), or ectopic

36
Q

Primary hyperparathyroidism can be due to

A

excessive secretion of parathormone due to:
benign adenoma (80-90%)****
hyperplasia (15%)
carcinoma (<1-5%)

37
Q

With primary hyperparathyroidism, over

A

50% of patients are asymptomatic

38
Q

Symptoms are more common at

A

calcium levels above 11.5-12 mg/dL

39
Q

Manifestations of hypercalcemia involve primarily the

A

kidneys and skeletal system- calcium deposits in renal parenchyma or recurrent nephrolithiasis and skeletal pathology

40
Q

Diagnosis of hyperparathyroidism

A 
PTH assay
calcium levels
vitamin D levels
renal function
CT scans
has anything happened to the neck?
albumin?
41
Q

Medical management of hyperparathyroidism includes

A

used for mild, asymptomatic disease
mild hypercalcemia–>hydration
moderate to severe hypercalcemia (13-15)- IV saline hydration and furosemide to promote a Na/Ca diuresis

42
Q

Surgical management of hyperparathyroidism includes

A

definitive treatment
intraoperative PTH assay is measured before and at a 5-minute intervals after adenoma removal to confirm a rapid fall to normal

43
Q

With multiple-gland hyperplasia, all glands must be identified and either

A
  1. three are removed, with partial excision of the fourth (leaving a good blood supply)
  2. total parathyroidectomy is performed, with immediate transplantation of a removed, minced parathyroid gland into the forearm muscles
44
Q

Hypoparathyroidism is the

A

absence or deficiency in PTH secretion

resistance of peripheral tissues to the effects of the hormone

45
Q

Hypoparathyroidism results in

A

hypocalcemia

46
Q

Hypoparathyroidism tends to be

A

iatrogenic (removed surgically with thyroidectomy)

47
Q

Clinical signs of hypocalcemia include

A 
neuronal irritability
skeletal muscle spasms
tetany
seizures
fatigue and mental status changes
prolonged QT interval
Congestive heart failure (chronic)
hypotension (acute)
48
Q

Acute hypocalcemia can present with

A

stridor, laryngospasm, and apnea

49
Q

Tetany occurs because

A

normally calcium blocks sodium channels and inhibits depolarization of nerve and muscle fibers, reduced calcium lowers the threshold for depolarization

50
Q

Treatment for hypocalcemia includes

A

electrolyte replacement
calcium and vitamin D
hypomagnesemia is managed with oral or IV replacement

51
Q

Severe symptomatic hypocalcemia requires

A

10-20 mL of 10% calcium gluconate or 3-5 mL of 10% calcium chloride followed by a continuous infusion of calcium (1-2 mg/kg/hr)

52
Q

For anesthesia and hypocalcemia,

A

treat hypocalcemia prior to surgery

53
Q

Major anesthetic risks of hypocalcemia include

A

decreased cardiac contractility and dysrhythmias
tetany
altered response to muscle relaxants
risk for laryngospasm

54
Q

The treatment for overactive parathyroid gland is

A

surgical removal of the benign tumor

55
Q

Without treatment for overactive parathyroid gland,

A

problems of fatigue, bad memory, kidney stones, and osteoporosis will result

56
Q

Parathyroid surgery is performed

A

supine, arms tucked, gel head ring, 2 PIVs, antiemetic coverage, GA with NIMS monitoring ETT, inhalation agent, remifentanil infusion, no abx, ether screen and 2 clicks down on bed for neck extension

57
Q

The anesthetic management of parathyroidectomy includes:

A

concern for cardiac dysrhythmias secondary to elevated calcium–> hypercalcemia decreases the refractory period and increases ventricular excitability
NIMs ETT–> assess RLN
Careful positioning–> risk for fractures

58
Q

Postoperative complications of parathyroidectomy

A

are similar to thyroid surgery- recurrent laryngeal nerve injury, hematoma, hypocalcemia
-acute hypocalcemia- only if severe deficit preop or injury to all parathyroid glands

59
Q

The effects of neuromuscular blocking agents with parathyroidectomy are

A

unpredictable secondary to hypercalcemia- consider qualitative NMB monitoring

60
Q

Parathyroid surgery uses

A

large IV for PTH sampling
if it is impossible to site a peripheral IV that will drawback then an arterial line may be needed
consider saphenous IV
position NIBP cuff (above PTH sample IV) to function as a tourniquet

61
Q

PTH sampling during surgery involves

A
  1. baseline PTH sample
  2. scheduled PTH samples in OR are at:
    - -> time 0 (at removal of parathyroid as alerted by surgeon)
    - -> time 5, 10, and 15 min post parathyroid removal

Pathophys II (43 decks)

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