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Mercy CLS 5: Chemistry > 13) Bone and mineral > Flashcards

13) Bone and mineral Flashcards

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1
Q

hydroxyapatite

A

Crystal lattice composed of calcium, phosphorus, and hydroxide

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2
Q

forms of Ca in blood

A

iCa — free or ionized – active form (50%)
Complexes with anions (10%)
Bound to protein (40%)

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3
Q

anions that bind Ca

A

Bicarbonate
Lactate
Phosphate
Citrate

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4
Q

The —– affects how well serum proteins bind free calcium.

How?

A

pH

Alkalosis: increased negative charges = increased binding of free calcium= ↓iCa
Acidosis: decreased negative charge = decreased binding of free calcium= ↑iCa

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5
Q

For each —– unit change in pH, there is a —- mg/dL inverse change in serum free calcium.

A

0.1
0.2

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6
Q

Distribution of Ca bound to proteins

A

80% to albumin
20% to globulins

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7
Q

Low proteins = low total ——-

A

calcium

Pseudohypocalcemia

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8
Q

——- is independent of protein levels, where ——- is dependent

A

iCa
total Ca

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9
Q

corrected total Ca for when albumin is not in normal range

A

Corrected Total Ca = Total Ca + [(normal albumin – patient albumin)0.8]

Cannot apply this in states of acidosis or alkalosis

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10
Q

total Ca RR

A

8.6-10.0 mg/dL

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11
Q

PTH effect on Ca levels

A

↑serum iCa, ↓ Phos

Mg needed

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12
Q

1,25-dihydroxycholecalciferol/Vitamin D3 effect on Ca levels

A

↑serum iCa, ↓ Phos

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13
Q

functions of Ca

A

Nerve impulse transmission
Cofactor in certain enzymes
Coagulation of blood
Skeletal mineralization
Preservation of cell membrane integrity and permeability

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14
Q

PTH acts on the…

A

kidney (Ca reabsorption, P secretion)
intestine (Ca absorption)
bone (resorption)

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15
Q

why is iCa the best measure of Ca status?

A
  • Biologically active.
  • Tightly regulated by parathyroid hormone (PTH) and vitamin D.
  • Measured in blood using ion-selective electrodes.
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16
Q

——- iCa values can cause seizures or cardiac arrest.

A

Low

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17
Q

—— iCa can cause nausea, constipation, and kidney failure if calcium salts are precipitated in the kidneys.

A

High

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18
Q

iCa concentration in plasma or serum is sensitive to both….

sample handling?

A

pH and temperature

Analyze within 30 mins, or within 4 hours on ice.
Analyzed immediately after uncapping the specimen.

pH should be measure with iCa. iCa and pH have an inverse relationship.

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19
Q

iCa RR

A

4.64 – 5.28 mg/dL

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20
Q

Increased urinary calcium concentration may be associated with an increase in….

A

osteoclastic bone resorption

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21
Q

urine Ca sample handling

A

24-hour urine specimens should be acidified with 5.0 mL of 6M HCL; solubilizes Ca crystals.

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22
Q

3 methods used to measure Ca

A

Colorimetric analysis
Atomic absorption
Indirect potentiometry

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23
Q

Approximately —% of extracellular phosphate occurs in inorganic form as hydroxyapatite crystals.

In plasma, most phosphate exists in the ——- form as mono- or dihydrogen phosphate ions.

A

85

inorganic

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24
Q

P RR

A

2.5-4.5 mg/dL

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25
Q

effects on intestinal and renal absorption of P

A
  • absorption ↑ when there is a ↓ in dietary Ca
  • Vit D ↑ absorption/reabsorption
  • GH ↓ renal reabsorption
  • PTH inhibits renal reabsorption
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26
Q

Reaction of ——– ion with ammonium molybdate to form a phosphomolybdate complex

A

phosphate

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27
Q

3 forms of circulating Mg

A

Free or ionized (55%)
Bound to proteins (30%)
Forming complexes with phosphate, citrate, and other ions (15%)

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28
Q

Since little Mg is found in plasma, what is recommended for measuring?

A

Suggested to measure in RBCs, mononuclear blood cells, or muscle biopsies.

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29
Q

Mg functions

A
  • Serves as a cofactor for more than 300 enzymes.
  • Cellular energy metabolism and membrane stabilization
  • Nerve conduction
  • Ion transport
  • Ca2+ channel activity
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30
Q

improves Mg absorption in small intestine

A

calcitriol

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31
Q

majority of Mg reabsorption occurs in the…

A

thick ascending loop of Henle (60%)

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32
Q

urine Mg sample handling

A

Samples collected in metal free tubes without preservatives (No EDTA, fluoride, or oxalate)

pH adjusted to 1 prior to running the assay

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33
Q

Gold standard for determining body magnesium status

Determines Mg deficiency

A

parenteral magnesium loading test (MLT)

Excretion of <70% of infused Mg = Mg deficiency

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34
Q

pH relationship to Mg

A

↑ pH = iMg ↓
↓ pH = ↑ iMg

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35
Q

Ortho-cresolphthalein complexone (CPC or OCPC) and arsenazo III

A

total Ca indicators

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36
Q

calmagite, methylthymol blue, formazan dye, mango or xylidyl blue, chlorophosphonazo III, and arsenazo

A

total Mg indicators

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37
Q

Secreted as an intact hormone, but breaks up into fragments in circulation

A

PTH

38
Q

relationship of Ca to PTH

A

↑ calcium concentration = ↓ PTH
↓ calcium concentration = ↑ PTH

39
Q

PTH 3 effects on kidneys

A
  • ↑ Ca reabsorption
  • ↑ P excretion
  • ↑ conversion of 1,25(OH)2 to Vit D3
40
Q

promotes meal-related intestinal absorption of Ca

A

activated vit D3

41
Q

Vitamin —– comes from food/supplements ingested (body can’t produce)

A

D2

42
Q

Vitamin —–, or ————, is a prohormone that can be transformed into physiologically active compounds by irradiation with ultraviolet light.

A

D3
cholecalciferol

43
Q

Pre-vitamin D is either ingested or synthesized in the skin from ————– through exposure to sunlight.

A

7-dehydrocholesterol

44
Q

inert Vit D3 is transported to the —— and converted to ———

A

liver
D25

45
Q

In the kidney, vit D25 undergoes further hydroxylation to become…

A

vit D1,25 (most active form)

46
Q

vitamin D deficiencies

A
  • Causes rickets among children
  • Precipitates and exacerbates osteoporosis among adults
  • Causes the painful bone disease osteomalacia.
47
Q

optimal D25 RR

A

20-50 ng/mL

48
Q

Calcitonin is synthesized and secreted by the parafollicular cells of the ———–.

A

thyroid gland

49
Q

Major calcium-regulating hormone because it tends to lower calcium and phosphorus

A

calcitonin

50
Q

Calcitonin tends to be increased in…

A

medullary thyroid carcinoma

51
Q

Used therapeutically for treatment of osteoporosis and Paget’s Disease

A

calcitonin

52
Q

2 principle causes of hypercalcemia

A

Malignancy (low PTH)
Primary hyperparathyroidism (high PTH)

53
Q

2 types of hypercalcemic malignancies

A

Local osteolytic hypercalcemia
Humeral hypercalcemia of malignancy (HHM)

54
Q

More serious symptoms are laryngeal spasm, convulsion, respiratory arrest, and tetany

A

hypocalcemia

55
Q

Characterized by excessive secretion of PTH in the absence of an appropriate physiological stimulus.

A

Primary Hyperparathyroidism (PHPT)

56
Q

> 60% of PHPT patients are ….

A

postmenopausal women

57
Q

better diagnostic measure for PHPT

A

iCa better than total Ca

58
Q

preferred sample for intraoperative management of parahyperthyroidism

A

K3-EDTA

59
Q

Chronic kidney disease compromises how the kidney functions
Fail to reabsorb Ca back into the blood (↑ urine Ca, ↓ serum Ca)
Fail to excrete phosphorus (↓ urinary phos, ↑ serum phos)
Fail to convert Vit D 25 to Vit D 1,25

A

secondary hyperparathyroidism

60
Q

secondary HPT tx

A

vitamin D

61
Q

tertiary hyperparathyroidism found in 1/3 of…

A

renal transplant patients

62
Q

1-3% of patients require parathyroidectomy

A

Tertiary Hyperparathyroidism

63
Q

hypoparathyroidism most commonly caused by…

A

parathyroid gland destruction during neck surgery (90%)

64
Q

PTH, Ca, and P all increased

A

tertiary HPT

65
Q

If phosphate levels remain elevated for a period of time, ———— may occur.

A

ectopic calcification

66
Q

levels decrease to about ½ the lower limit of normal

Respiratory failure
Impairment of cardiac contractility

A

hypophosphatemia

67
Q

present with significantly elevated blood levels of magnesium

A

pregnant patients given magnesium supplements to treat preeclampsia or eclampsia

68
Q

bone collagen structural feature

A

triple helix

69
Q

formation of collagen fibrils

A

Fibrillogenesis

70
Q

Collagen ——– represents the major component of bone.
Collagen ——– is the main component of cartilage.

A

type I
type II

71
Q

functions of bone

A
  • Providing mechanical protection for internal organs
  • Allowing the direction of motion
  • Facilitating the locomotion process
  • Providing a protective housing for blood-forming marrow
  • Serving as a reservoir for mineral ions
72
Q

composition of bone

A

~60% minerals
~35% organic matrix
~ 5% cells, and water

73
Q

Refers to the ordered deposition of apatite on a type I collagen matrix.

A

bone mineralization

74
Q

Formation of bone on sites where it has not been before.

A

bone modelling

75
Q

Formation of bone on surfaces previously containing bone.

A

bone remodelling

76
Q

Refers to the amount of bone renewed during the bone remodeling process.

A

bone turnover

77
Q

2 major types of bone

A

cortical
trabecular

78
Q

Occur as a layer of contiguous cells that in their active state are cuboidal.

A

osteoblasts

79
Q

Represent the most abundant cell in the skeleton

A

osteocytes

80
Q

Major stimulator of both the differentiation of preosteoclasts to osteoclasts and the activity of the mature osteoclast.

A

Receptor activator of nuclear factor kappa B-ligand (RANK-L)

81
Q

Protects the bone from osteoclastic activity by binding RANK ligand

A

Osteoprotegerin

82
Q

ideal bone biomarker

A
  • Structural protein released into the blood in a rate proportional to its incorporation into bone.
  • Fraction released should be unchanged by disease.
  • Should have a well-characterized function and should not be released unaltered during bone resorption.
  • Metabolic pathway and serum half-life should be known.
  • A bone marker should be a degradation product of a matrix component not found in any other tissue.
  • Serum levels of bone resorption markers should not be under separate endocrine control.
  • The marker should not be reused in new bone formation.
83
Q

gold standard bone techniques

A
  • Isotope bone scan
  • Bone biopsy (histomorphometry)
  • Whole body calcium kinetic studies.
84
Q

osteoporosis

A

A progressive systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fractures.

85
Q

most common type of primary osteoporosis

A

menopausal

86
Q

Side effect following transplant of kidney, heart, liver, lung, and bone marrow

pathogenesis not understood

A

secondary osteoporosis

87
Q

———— significantly enhance the loss of bone and increase the incidence of bone fractures

A

immunosuppressant drugs

88
Q

osteoporosis r/f

A

Caucasian race
Older age
Postmenopausal
Decreased dietary calcium
Decreased vitamin D
Physical inactivity
Tobacco use
Excess alcohol intake
Exposure to medications (e.g., loop diuretics, glucocorticoids, and anticoagulants)

89
Q

Leads to widening of the epiphyseal plate, skeletal abnormalities, and possible growth retardation

A

rickets

90
Q

Chronic, localized disease characterized by increased bone remodeling, bone hypertrophy, and abnormal bone structure

A

Paget’s disease

Mercy CLS 5: Chemistry (24 decks)

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