Calcium (F)

Question 1

What is calcium (Ca)?

Answer 1

It is the most abundant mineral in the body

Question 2

What are the fxns of Ca?

Answer 2

1) It fxns for blood coagulation
2) It fxns in enzyme activity
3) It fxns in the excitability of skeletal and cardiac muscle
4) It maintains blood pressure

Question 3

What is the distribution of Ca (/ where can Ca be found)?

Answer 3

99%: found in bones

1%: found in blood and extracellular fluid (ECF)

Question 4

What are the different forms of Ca (and their corresponding percentages)?

Answer 4

1) Ionized / free Ca: 45%
2) Total / bound Ca: 40%
3) Complexed w/ anions: 15%

Question 5

Where is total / bound Ca binded?

Answer 5

Albumin

Question 6

What are the anions that where Ca is complexed (for Ca that are complexed w/ anions)?

Answer 6

1) Phosphate

2) Citrate

Question 7

What are the factors that affects the conc. of Ca in the blood?

Answer 7

1) 1,25 dihydroxycholecalciferol / 1,25-(OH)2-D3
2) Parathyroid hormone (PTH)
3) Calcitonin

Question 8

What are the fxns of PTH?

Answer 8

1) It conserves Ca by increasing reabsorption in the kidneys
2) It activates bone resorption
3) It suppresses the urinary loss of Ca
4) It activates the conversion of inactive vit D3 in the kidneys

Question 9

What are the fxns of 1,25 dihydroxycholecalciferol?

Answer 9

1) It increases intestinal absorption of Ca
2) It increases reabsorption in the kidneys
3) It increases mobilization of Ca from bones (bone resorption)

Question 10

What secretes calcitonin?

Answer 10

Parafollicular C cells

Question 11

Where are parafollicular C cells present?

Answer 11

These are present in the thyroid gland

Question 12

What are the fxns of calcitonin?

Answer 12

1) It inhibits PTH and vit D
2) It inhibits bone resorption
3) It promotes urinary excretion of Ca

Question 13

What are the concepts that are related w/ hypocalcemia?

Answer 13

1) Vit D deficiency
2) Primary hypoparathyroidism
3) Hypomagnesemia
4) Pancreatitis
5) Renal tubular failure
6) Rhabdomyolysis

Question 14

What are the concepts that are related w/ hypercalcemia?

Answer 14

1) Primary hyperparathyroidism
2) Malignancies
3) Hyperthyroidism
4) Thiazide diuretics
5) Prolonged immobilization

Question 15

What are the sx considerations for Ca determination?

Answer 15

1) Serum / heparinized plasma should be used
2) EDTA and oxalate anticoagulants are unacceptable
3) Prolonged tourniquet application and forearm exercise should be avoided
4) The sx should not be exposed to air

Question 16

What is the composition of rgnt set for Ca determination?

Answer 16

1) Buffer

2) Color rgnt

Question 17

What is the principle of the test for Ca determination?

Answer 17

Colorimetric

Cresolphthalein complexone reacts w/ Ca ions (present in alkaline medium) forming a red-violet color

Question 18

What is the principle of rxn for Ca?

Answer 18

o-Cresolphthalein + Ca^++ (in the presence of OH^-) -> Ca^++ CPC complex

Question 19

What should be added to eliminate the interference of Mg?

Answer 19

8-hydroxyquinoline

Question 20

What is the process (/ steps) for Ca determination?

Answer 20

1) Prep the machine and the Ca rgnt (/ Ca working rgnt)
2) Prep the ff tubes (blank, standard, and sample) and add the working rgnt (1,000 uL)
3) Add the sx (20 uL) to the respective test tubes and incubate for 1 min
a. Blank: distilled H2O
b. Standard: Ca std
c. Sample: serum / heparinized plasma
4) Read and record A at 570 nm

Question 21

What is the volume of Ca working rgnt?

Answer 21

1,000 uL

Question 22

What is the volume of the sx?

Answer 22

20 uL

Question 23

What is the normal reference range for Ca?

Answer 23

8.5 - 10.5 mg/dL