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Endocrinology > Exam 3: Calcium/phosphate > Flashcards

Exam 3: Calcium/phosphate Flashcards

1
Q

Total Ca2+ concentration in blood

A

10 mg/dl

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2
Q

40% of total blood calcium is bound to ____ and 60% is ____

A

Plasma proteins; unbound

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3
Q

Of the unbound calcium 10% is complexed to which anions

A

Phosphate
Sulfate
Citrate

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4
Q

Of the unbound calcium 50% is

A

Ionized Ca2+

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5
Q

What is the only form of calcium that is biologically active

A

Ionized Ca2+

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6
Q

Hypocalcemia has what effects on body

A 
Hyper-reflexia
Spont. Twitching
Muscle cramps
Tingling
Numbness
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7
Q

Hypocalcemia lowers the threshold potential of

A

Muscle and nerves

Easier to excite

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8
Q

Chvostek sign = twitching of facial muscles elicited by

A

Tapping on CN7

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9
Q

Trousseau sign is a carpopedal spasm after

A

Inflation of sphygmomanometer (BP cuff)

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10
Q

Hypercalcemia neurologic signs

A

Hyporeflexia
Lethargy
Coma — death

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11
Q

Hypercalcemia can also lead to

A

Constipation
Polyurea
Polydipsia

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12
Q

Increase in concentration is associated with

A

Inc in total Ca2+

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13
Q

Changes in anion concentration is ____ proportional to changes in ionized Ca2+

A

Indirectly

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14
Q

Acidemia ultimately causes _____ in ionized Ca2+

A

Inc

Bc more H+ binds to albumin, displaces Ca2+

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15
Q

Alkalemia ultimately causes ____ in ionized Ca2+

A

Dec

Bc less H+ binds to albumin

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16
Q

Calcium homeostasis involves 3 organ systems

A

Bone
Kidney
Intestine

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17
Q

Overall calcium homeostasis involves 3 hormones

A

PTH
Calcitonin
Vitamin D

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18
Q

Role of PTH

A

Regulate Ca2+ ECF concentration

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19
Q

Dec plasma Ca2+ causes ____ PTH from parathyroid glands

A

Inc secretion

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20
Q

____ cells synthesize and secrete PTH

A

Chief

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21
Q

Secretion of PTH is regulated by

A

Plasma Ca2+ concentration

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22
Q

PTH is secreted when plasma Ca2+ concentration goes below _____

A

10 mg/dl

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23
Q

Maximal secretion of PTH occurs at

A

7.5 mg/dl

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24
Q

Chronic hypocalcemia leads to

A

Secondary hyperparathyroidism

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25
Q

Chronis hypercalcemia leads to

A

Dec synthesis/storage of PTH

Inc breakdown of stored PTH

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26
Q

Magnesium effect on PTH

A

Similar to Ca2+

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27
Q

Hypomagnesia

A

Stims PTH secretion

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28
Q

Severe hypomagnesia is associated w/

A

Alcoholism

Inhibits PTH synthesis, storage and secretion

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29
Q

Hypermagnesia

A

Inhibits PTH secretion

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30
Q

At the renal proximal tubule PTH inhibits _____ and results in

A

Renal phosphate reabsorption; phosphaturia

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31
Q

At the distal convoluted tubule PTH stimulates

A

Ca2+ reabsorption

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32
Q

PTH has ____ effect on kidney mediated by cAMP

A

Direct

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33
Q

PTH has ____ effect on intestine via activation of Vit D

A

Indirect

Inc calcium absorption via Vit D

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34
Q

PTH in bone: receptors located only on

A

Osteoblasts

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35
Q

PTH initially and briefly ____ bone formation

A

Inc

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36
Q

PTH causes an ___ in bone resorption

37
Q

Net effect of PTH over long haul in bone is

A

Bone resorption

Causes inc in Ca2+ and phosphate to ECF

38
Q

PTH stimulates renal 1a-hydroxylase which converts

A

25-hydroxycholecalciferol — 1,25 dihydroxycholecalciferol

39
Q

1,25 dihydroxycholecalciferol AKA

A

Active form of vitamin D

40
Q

Active vitamin D stimulates

A

Intestinal Ca2+ absorption

41
Q

Primary hyperparathyroidism MC caused by

A

Parathyroid adenoma

42
Q

Primary hyperparathyroidism causes glands to secrete lots of PTH which causes

A

Hypercalcemia

Hypophosphatemia

43
Q

Primary hyperparathyroidism causes excretion of excessive amounts of

A

Ca2+
CAMP
Phosphate

All can form kidney stones

44
Q

Kidney stones are formed as a result of Ca2+ precipitating as

A

Ca2+ phosphate
Ca2+ oxalate

Primary hyperparathyroidism

45
Q

Secondary hyperparathyroidism

A

Parathyroid normal

Stim to secrete PTH secondary to hypocalcemia

46
Q

Hypocalcemia in secondary hyperpara due to

A

Vit D deficiency

Chronic renal failure

47
Q

Other aspects of secondary hyperparathyroidism

A

High PTH

Low/normal plasma Ca2+

48
Q

How to differentiate primary and secondary hyperparathyroidism

A

Plasma Ca2+ low/normal (secondary)

Plasma Ca2+ high (primary)

49
Q

Hypoparathyroidism is a common consequence of

A

Thyroid surgery

50
Q

Hypoparathyroidism causes

A

Low PTH
Hypocalcemia
Hyperphosphatemia

51
Q

Pseudohypoparathyroidism

A

Gs receptor protein for PTH in kidney/bone is defective

Doesn’t activate adenylyl cyclase

52
Q

Pseudohypoparathyroidism AKA

A

Albright’s hereditary osteodystrophy

53
Q

Pseudohypoparathyroidism causes

A

Hypocalcemia

Hyperphosphatemia

54
Q

Pseudohypoparathyroidism physical characteristics

A

Short stature/neck
Obesity
Subcutaneous calcification
Shortened 4th metacarpals/tarsals

55
Q

Humoral hypercalcemia of malignancy

A

Malignant tumors secrete peptide that is similar to PTH

56
Q

Humoral hypercalcemia of malignancy causes

A

Hypercalcemia

Hypophosphatemia

57
Q

Humoral hypercalcemia of malignancy has similar findings to primary hyperpara except

A

Low PTH

Suppressed by hypercalcemia

58
Q

Humoral hypercalcemia of malignancy is treated w/

A

Furosemide — inhibits renal Ca2+ reabsorption

Etidronate — inhibits bone resorption

59
Q

Familial hypocalciuric hypercalcemia characterized by

A

Dec urinary Ca2+ excretion

Inc plasma Ca2+

60
Q

FHH caused by mutation of Ca2+ receptors in

A

Parathyroid glands

Kidney

61
Q

FHH has ___ PTH levels

A

high (not inhibited as it should be)

62
Q

Calcitonin is synthesized by

A

Parafollicular cell of thyroid

63
Q

Calcitonin is stored in

A

Secretory granules

64
Q

What stimulates calcitonin secretion

A

Inc plasma Ca2+

65
Q

Calcitonin inhibits ____ which leads to ___ plasma Ca2+

A

Osteoclast bone resorption; Dec

66
Q

Vitamin D promotes

A

Mineralization of new bone

67
Q

Vitamin D increases plasma levels of

A

Ca2+ and phosphate

68
Q

Vitamin D is a ___ hormone

69
Q

Major site of action of vitamin D

70
Q

In intestine vitamin D inc _____ absorption

A

Ca2+ and phosphate

71
Q

Vitamin D induces synthesis of

A

Calbindin D-28 K

72
Q

Calbindin D-28 K

A

Protein that binds 4 Ca2+

May act as shuttle or help to maintain gradient

73
Q

Vitamin D actions in kidney

A

Inc Ca2+ and phosphate

74
Q

Vitamin D in bone, acts synergistically w/ ___ to stimulate ____

A

PTH; osteoclast activity and bone resorption

75
Q

Vitamin D deficiency in children

76
Q

Rickets: insufficient amounts of ____ which causes ____

A

Ca2+ and phosphate

Growth failure/skeletal deformities

77
Q

Vitamin D deficiency in adults

A

Osteomalacia

78
Q

Osteomalacia characterized by

A

New bones failing to mineralize — softening of bones

79
Q

Deficiency of vitamin D effect on other organs

A 
CV disease
Cancer
Infection
MS
Childhood asthma
80
Q

Other functions of vitamin D

A 
Controls genes
Dec cell proliferation
Immunomodulator
Controls inflamm
Muscle strength
BP
81
Q

Vitamin D deficiency effect on muscles

A

Muscle weakness

82
Q

Vitamin D effect on BP

A

Inhibits renin secretion

83
Q

Vitamin D effect on inflamm

A

Lack of Vit D = inc CRP and IL-10

84
Q

In response to TB/LPS Vitamin D genes are upregulated which causes inc production of

A

Cathelicidin — powerful antimicrobial

85
Q

Chronic renal failure characterized by dec production of

A

Active Vit D

86
Q

Chronic renal failure has ___ PTH levels and ___ bone resorption of Ca2+

87
Q

Chronic renal failure causes

A

Osteomalacia

88
Q

Chronic renal failure exhibits ___ urine phosphate which ___ plasma phosphate

89
Q

Chronic renal failure ___ plasma Ca2+

Endocrinology (11 decks)

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