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MM Test 3 > B6.050 Prework 1: Hyperparathyroidism > Flashcards

B6.050 Prework 1: Hyperparathyroidism Flashcards

1
Q

how many parathyroid glands are there

A

85% of people have 4

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2
Q

origin of superior parathyroid glands

A

arise from 4th brachial pouch

more constant in location than inferior glands

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3
Q

location and blood supply of superior parathyroid glands

A

usually within 1 cm of where the recurrent laryngeal nerve pierces the cricothyroid membrane
perfused by inferior thyroid artery

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4
Q

origin of inferior parathyroid glands

A

arise from 3rd brachial pouch

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5
Q

location and blood supply of inferior parathyroid glands

A 
typically within 1 cm of where inferior parathyroid artery enters the thyroid
more often ectopic than superior glands
-tracheoesophageal groove
-paratracheal fat
-thymus
perfused by the inferior thyroid artery
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6
Q

common locations of ectopic parathyroid glands

A 
15% within the thymus
1% intra thyroidal
3-5% within the posterior mediastinum or carotid sheath
aortopulmonary window
paraesophageal
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7
Q

primary cell of parathyroid

A

chief cells

properties vital to homeostatic function

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8
Q

function of chief cells

A

rapidly secrete stored PTH hormone in response to changes in blood calcium (seconds)
synthesize, process, and store large amounts of PTH in a regulated manner (hours)
replicate when chronically stimulated (days)

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9
Q

description of PTH production

A

synthesized as a larger precursor
pre-pro-PTH (115 AA)
transit across ER, pre sequence cleaved
in Golgi, pro sequence cleaved

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10
Q

biologically active form of PTH

A

intact PTH, 84 AA

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11
Q

function of PTH

A

peptide hormone that control the minute to minute level of serum ionized Ca2+

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12
Q

where are surface receptors for PTH located

A

bone and kidney

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13
Q

major physiological responses to PTH

A

bone resorption
renal reabsorption
increased renal synthesis of 1,25(OH)2D3
increased intestinal absorption of dietary calcium

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14
Q

how does PTH influence phosphate reabsorption in kidney

A

decreased reabsorption of phosphate

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15
Q

how does PTH influence phosphate absorption in intestines

A

increased absorption of phosphate

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16
Q

what receptor on the chief cell senses calcium levels in serum

A

CaSRs on cell surface

member of G protein coupled family of receptors

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17
Q

response to hypocalcemia

A

increased PTH secretion

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18
Q

response to hyperphosphatemia

A

VERY increase PTH secretion

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19
Q

action of calcitriol on PTH levels

A

inhibits PTH synthesis by interacting with vitamin D receptor

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20
Q

metabolism of PTH

A

half life = 4 min

metabolized by liver (70%) and kidney (20%)

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21
Q

impact of familial hypocalciuric hypercalemia on function of parathyroid

A

inactivating mutation
parathyroid glands less sensitive to calcium
at kidney increased reabsorption of Ca2+ and Mg
increased PTH, Ca2+, and Mg
decreased urine calcium

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22
Q

impact of familial hypoparathyroidism with hypercalciuria

A

activating mutation of the CaSR
decreased serum calcium and PTH
increased urine calcium

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23
Q

dietary forms of vit D

A

D3: cholecalciferol (animal products)
D2: ergocalciferol (plants)
+
7-dehydrocholesterol from UV light

24
Q

liver metabolism of vit D

A

activated to calcidiol (25OH vit D)
circulating form
this form is measured for vit D status
2-3 week half life

25
Q

kidney metabolism of vit D

A

activated to calcitriol (1,25(OH)2 vit D)
6-8 hour half life
exerts effects on body (increased intestinal Ca absorption, increased bone resorption, decreased renal Ca and phosphate excretion)

26
Q

direct effects of 1,25(OH)2D3

A

active form
binds to vitamin D receptor
promotes enterocyte differentiation / intestinal absorption of Ca and PO4
direct suppression of PTH release
regulation of osteoblast function
permissively allows PTH induced osteoclast activation and bone resorption

27
Q

mnemonic for signs and symptoms of primary HPTH

A

stones
bones
groans
psychiatric overtones

28
Q

renal symptoms of HPTH

A 
renal stones
nephrocalcinosis
polyuria
polydipsia
uremia
29
Q

MSK symptoms of HPTH

A

osteitis fibrosa
radiologic osteoporosis
osteomalacia or rickets
arthritis

30
Q

abdominal symptoms of HPTH

A

constipation
indigestion, nausea, vomiting
peptic ulcer
pancreatitis

31
Q

psych symptoms of HPTH

A 
lethargy, fatigue
depression
memory loss
psychosis-paranoia
personality change
confusion, stupor, coma
32
Q

Ca2+ correction equation

A

corrects serum calcium for albumin

(4-Alb)*0.8 + Ca

33
Q

etiologies of hypercalcemia w/ elevated or mid to high normal PTH

A

pHPTH
FHH
differentiate by urine excretion (FHH is low, pHPTH is high)

34
Q

etiologies of hypercalcemia w/ low PTH

A

non-PTH mediated

measure PTH related peptide (PTHrp) and vit D metabolites

35
Q

PTHrp elevated

A

scan for malignancy

36
Q

elevated 1,25D

A

chest x-ray for lymphoma, sarcoid

37
Q

elevated 5D

A

check meds, vitamins, supplements

38
Q

management of mild hypercalcemia

A

<12 mg/dL

no immediate treatment

39
Q

management of severe hypercalcemia

A

> 14 mg/dL
volume expansion with isotonic saline
administer calcitonin
administer IV bisphosphonate

40
Q

primary cause of pHPTH

A

parathyroid adenoma (89-95%)
single gland
mostly composed of chief cells
oxyphil cells to a lesser extent

41
Q

other causes of pHPTH

A 
parathyroid hyperplasia (6%)
-four glands affected equally
-chief cell hyperplasia
parathyroid carcinoma (rare)
-very increased PTH (hundreds)
-Ca2+ > 14
42
Q

epidemiology of pHPTH

A

women most commonly affected
1% of gen pop
2% elderly pop

43
Q

diagnosis of pHPTH

A

increased serum chloride to phosphorus ratio >33:1

44
Q

surgical indications for pHPTH

A 
symptomatic disease (bones, stones, groans, psych overtones)
asymptomatic disease
- Ca over 1 mg/dL above upper limit
-creatinine clearance <60
-osteoporosis
-<50 years old
45
Q

FHH description

A 
benign, no ttx indicated
autosomal dominant
mild hypercalcemia with hypocalciuria
normal to slightly elevated PTH
high-normal to frankly elevated serum Mg level
46
Q

secondary HPTH

A

seen in patients with renal failure
an appropriate increase in PTH responds to chronically low calcium
most DO NOT need surgery

47
Q

treatment of secondary HPTH

A

dietary restrictions
phosphorus binding gels
calcium dialysate options

48
Q

eventual fate of parathyroid glands in secondary HPTH

A

eventually become autonomous

-even with correction of serum calcium via renal transplant, PTH remains inappropriately elevated (TERTIARY HPTH)

49
Q

surgery for secondary/tertiary HPTH

A

subtotal (3.5) / total parathyroidectomy with reimplantation

50
Q

what is hypercalcemia of malignancy?

A

present in 20% of cancer patients (esp lung)
malignant cells elaborate humoral mediators of hypercalcemia (PTHrp)
rarely result from direct bony destruction by tumor ingrowth

51
Q

endogenous PTH in hypercalcemia of malignancy

A

scarce or undetectable

requires suspicion of malignancy on part of physician

52
Q

cortical bone

A

outer part
dense and compact
maintains structural function of bone

53
Q

metabolic function of skeleton

A

storage for calcium, phosphorus, and carbonate

54
Q

trabecular bone

A

inside long bones and vertebrae

maintains metabolic function of bone

55
Q

T score

A

number of standard deviations from young adult mean density

56
Q

Z score

A

number of standard deviations from age matched mean density

applies to pre-menopausal females and males <50

MM Test 3 (31 decks)

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