Calcium (F) Flashcards
What is calcium (Ca)?
It is the most abundant mineral in the body
What are the fxns of Ca?
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
What is the distribution of Ca (/ where can Ca be found)?
99%: found in bones
1%: found in blood and extracellular fluid (ECF)
What are the different forms of Ca (and their corresponding percentages)?
1) Ionized / free Ca: 45%
2) Total / bound Ca: 40%
3) Complexed w/ anions: 15%
Where is total / bound Ca binded?
Albumin
What are the anions that where Ca is complexed (for Ca that are complexed w/ anions)?
1) Phosphate
2) Citrate
What are the factors that affects the conc. of Ca in the blood?
1) 1,25 dihydroxycholecalciferol / 1,25-(OH)2-D3
2) Parathyroid hormone (PTH)
3) Calcitonin
What are the fxns of PTH?
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
What are the fxns of 1,25 dihydroxycholecalciferol?
1) It increases intestinal absorption of Ca
2) It increases reabsorption in the kidneys
3) It increases mobilization of Ca from bones (bone resorption)
What secretes calcitonin?
Parafollicular C cells
Where are parafollicular C cells present?
These are present in the thyroid gland
What are the fxns of calcitonin?
1) It inhibits PTH and vit D
2) It inhibits bone resorption
3) It promotes urinary excretion of Ca
What are the concepts that are related w/ hypocalcemia?
1) Vit D deficiency
2) Primary hypoparathyroidism
3) Hypomagnesemia
4) Pancreatitis
5) Renal tubular failure
6) Rhabdomyolysis
What are the concepts that are related w/ hypercalcemia?
1) Primary hyperparathyroidism
2) Malignancies
3) Hyperthyroidism
4) Thiazide diuretics
5) Prolonged immobilization
What are the sx considerations for Ca determination?
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
What is the composition of rgnt set for Ca determination?
1) Buffer
2) Color rgnt
What is the principle of the test for Ca determination?
Colorimetric
Cresolphthalein complexone reacts w/ Ca ions (present in alkaline medium) forming a red-violet color
What is the principle of rxn for Ca?
o-Cresolphthalein + Ca^++ (in the presence of OH^-) -> Ca^++ CPC complex
What should be added to eliminate the interference of Mg?
8-hydroxyquinoline
What is the process (/ steps) for Ca determination?
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
What is the volume of Ca working rgnt?
1,000 uL
What is the volume of the sx?
20 uL
What is the normal reference range for Ca?
8.5 - 10.5 mg/dL
