Mg, Ca, PO4, and Bone Disease

Question 1

How much of bone is minerals vs. collogen

Answer 1

2/3 minerals + 1/3 organic collogen material

Question 2

4 Parts of Bone Anatomy

Answer 2

Periosteum – tough fibrous outer membrane with blood vessels and nerves

Compact Bone – hard tube beneath the periosteum

Spongy Bone – honeycomb structure at end of long bones that provides weight bearing strenght

Marrow – red vs yellow marrow

Question 3

Red vs. Yellow Marrow

Answer 3

1. Red Marrow – produces RBCs in spongy bone of long bones and flat bones of the skull, ribs, pelvis, breast bone, and spine
2. Yellow Marrow – fat reserve, in hollow bone shafts (femor/humorus)

Question 4

Where is PTH produced?

Answer 4

Parathyroid

Question 5

PTH Functions

Answer 5

PTH activates bone resorption
PTH increases renal re-absorption of Calcium
PTH stimulates renal production of active Vitamin D

excretion of Phosphates

Question 6

What conditions activate PTH

Answer 6

low serum levels of calciium

Question 7

What activates Vitamin D?

Answer 7

PTH

Question 8

Function of Vitamin D

Answer 8

Increases Calcium and Phosphate absorption by intestines

Enhances PTH effect on bone resorption

Question 9

Where is Calcitonin produced?

Answer 9

thyroid

Question 10

Calcitonin Function

Answer 10

Inhibits PTH action

Inhibits Vitamin D action

Question 11

What conditions initiate Calcitonin secretion

Answer 11

high serum levels of calcium

Question 12

How much of total calcium is stored in serum?

Answer 12

< 1.0%

45% free ionized, 40% bound to protein, 15% complexes

Question 13

TOTAL Calcium Normal Ranges:

Answer 13

Normal Child: 8.8 – 10.8 mg/dl

Normal Adult: 8.6 – 10.0 mg/dl

Question 14

Calcium Sample Requirements

Answer 14

Serum

Lithium heparin plasma

Question 15

Clinical Significance of Calcium Serum Levels

Answer 15

open heart or major surgery due to role in maintaining cardiac output/BP

Question 16

Calcium interfering substances

Answer 16

EDTA/Oxalate binds calcium

Aerobic collection decreases Calcium

Question 17

Calcium Methodology

Answer 17

Ion Selective Electrode

Orthocresolphthalein complexone (OCPC) – Ca binds forms purple complex

Chloranilic Acid

Fluorescene

Atomic Absorption

Question 18

Ionized Calcium

Answer 18

Neonate: 4.8 – 5.9 mg/dl
Normal Child: 4.8 – 5.5 mg/dl
Normal Adult: 4.6 – 5.3 mg/dl
24 hr Urine: 100 – 300 mg/day

Question 19

Location of Phosphates in body

Answer 19

80% Bone

20% Soft Tissue

<1% free unbound in Serum

Question 20

Phosphate Reference Ranges

Answer 20

Normal Neonates: 4.5 – 9.0 mg/dl
Normal Child: 4.5 – 5.5 mg/dl
Normal Adult: 2.2 – 4.5 mg/dl
Normal Urine: 0.4 – 1.3 g/day

Question 21

Phosphate Specimen Requirements

Answer 21

Serum

Lithium heparin plasma

Question 22

Phosphate Interfering Substances

Answer 22

Oxalate
citrate
EDTA (binds Ca+)
Hemolysis (intracellular phosphate released)
Collection time/circadian rhythm (24hr best)

Question 23

Phosphate Testing Methodology

Answer 23

formation of ammonium phosphomolybdate complex read by specrtophotometry

Question 24

Vitamin D clinical Significance

Answer 24

skeletal formation and mineral homeostasis

Question 25

Magnesium location in body

Answer 25

53% Bone 46% muscle, organ, soft tissue <1% serum)

Question 26

Magnesium Reference Values

Answer 26

Adult Normal: 1.6 – 2.7 mg/dl

Question 27

Magnesium Clinical Significance

Answer 27

``` cardiovascular metabolism neuromuscular Activator of enzymes for glycolosis ion pumps neuromuscular transmissions ```

Question 28

Magnesium Sample Requirements

Answer 28

Serum Lithium heparin plasma 24 hour urine (diurinal variation)

Question 29

Magnesium Interfering Substance

Answer 29

Hemolysis | higher concentration do to intracellular magnesium released

Question 30

Magnesium Methodology

Answer 30

reference: Atomic Absorption | Calmagite, formazen dye, methythymol blue colormetric complexes/spectrophotometry

Question 31

physiological formation of Vitamin D

Answer 31

1. Diet or sunlight exposure obtains Vitamin D3 (cholecalciferol) inactive form 2. Liver converts to 25-hydrozycholecalciferol inactive form (stored in liver and removed by bile excretion) 3. Kidney converts 1,25-dihydroxycholecalciferol into active form Decrease in serum calcium cause PTH production which increases the renal production of active Vita D. Active Vitamin D increases intestinal Calcium absorption and increases PTH effect on bone resorption

Question 32

Vitamin D Target Organs

Answer 32

Intestines: increases calcium and phosphorus absorption Bone: enhances PTH effects of bone resorption of calcium Kidney: promotes renal reabsorption of Calcium and Phosphorus

Question 33

Function of Calcitonin

Answer 33

inhibit PTH action Inhibit vitamin D action

Question 34

Relationship of Calcium and Phosphorus

Answer 34

Calcium forms complexes with phosphates in plasma Reciprocal of each other Increase calcium in plasma = decreases phosphates since it binds it all Increase Phosphates in plasma = decrease calcium since it binds it all

Question 35

tissue sources of alkaline phosphatase.

Answer 35

4 Isoenzymes: structurally different with same job Liver Bone Placenta Intestines

Question 36

Role of Alkaline Phosphatase

Answer 36

catalyzes hydrolysis of phosphoesters at alkaline pH to free phosphates from organic phosphate esters

Question 37

Indicators of disease based on Alkaline Phos

Answer 37

Liver damage = higher alkaline phosphatase / liver damage = free flow of alk phos into bile and blood Pregnancy = higher bone and placenta alkaline phosphatase levels Crush injury = higher bone alkaline phosphatase

Question 38

elevated Alkaline Phosphatase How to determine bone or liver cause?

Answer 38

1. measure total ALP activity 2. heat sample at 56oC for 10 Minutes 3. measure total ALP activity if 20% total activity = LIVER (heat stable: liver lasts)

Question 39

Majority location of Copper

Answer 39

90% bound with ceruloplasmin (synthesized in liver)

Question 40

Causes of Deficiency in Copper

Answer 40

due to malnutrition malabsorption increased Zinc (competes for absorption)

Question 41

Causes of Excess Copper

Answer 41

Increased injestion (copper bakeware)

Question 42

Menkes Syndrome

Answer 42

decreased copper Recessive x-linked genetic disorder Mental deterioration, failure to thrive, kinky hair, early death

Question 43

Wilson's Disease

Answer 43

increased copper (Copper excretion impaired) Autosomal recessive Kayser-Fleisher rings: copper deposits in ring around iris Treatment: Administer zinc to compete with copper

Question 44

Zinc

Answer 44

competes with copper and iron Fctn: growth, wound healing, reproduction, immune system (activator for 300+ enzymes) Deficient: malabsorption, chronic liver/kidney disease, alcoholism

Question 45

Maganese

Answer 45

transported by albumin and transferrin / associated with enzymes Higher concentration in RBC’s (don’t want hemolysis in testing

Question 46

Osteomalacia:

Answer 46

decreased mineralization of bone matrix Causes: Vitamin D deficiency (serum Calcium and Phos are low) Lab would see low serum Calcium and Phosphates

Question 47

Osteoporosis

Answer 47

decreased bone density / skeletal fragility