CALCIUM MEASUREMENT

Bones

blood

Calcium

Location: _ (99%), _ (1%)

Ionized Ca2+

Protein-bound Ca2+

Complex Ca2+

Calcium

Total Ca2+ in the blood is divided into 3 forms:

Ionized Ca2+

Calcium

3 forms:

Unbound, active, 45% of total Ca+2

Protein-bound Ca2+

Calcium

3 forms:

40% bound to albumin

Complex Ca2+

Calcium

3 forms:

10% carboxylated Ca+2

extracellular fluid

cytosol

Calcium

Remaining 1%: Found in the _ _; also found in the _ in the cells

Neuromuscular activity

Cardiac concentration

Cell permeability

Coagulation (Factor IV)

Structure of bones and teeth

Calcium

Functions (5)

200

Calcium is excreted at _ mg/day (urine and bile)

Parathyroid Hormone

Hypercalcemic Hormone

Parathyroid Hormone

Bone resorption – activated osteoclasts break down bones and subsequently release calcium levels into the bloodstream

Found in parathyroid glands

Activated Vitamin D (1,25-Dihydroxycholecalciferol)

Intestinal reabsorption and enhances the effect of PTH on bone resorption

Calcitonin

Hypocalcemic Hormone

Calcitonin

Bone deposition

Decreases calcium levels by making the calcium enter the bone repository

Hypocalcemia

PTH is activated due to the parathyroid gland sensing that there is hypocalcemia in the bloodstream

Parathyroid gland

secretes PTH which goes into the bone and kidney

Bone

PTH stimulates osteoclastic activity which releases Ca2+ and HPO4-

Kidney

PTH promotes absorption of Ca2+, excretion of HPO4-, and activation of renal 1-a-hydroxylase (important in the activation of Vitamin D)

Intestine

Once Vitamin D is activated:

Promotes intestinal absorption of Ca2+ and HPO4-

Kidney

Once Vitamin D is activated:

Promotes renal reabsorption of Ca2+ and HPO4-

Activated Vitamin D

Once Vitamin D is activated:

found in the small intestine

Hypercalcemia

When the parathyroid gland senses _ in the bloodstream, the secretion of PTH stops

Calcitonin

found in the medullary cells of the thyroid gland

2.13-2.63

2.24-2.53

REFERENCE RANGES FOR CALCIUM (BISHOP)
Total Calcium–Serum, Plasma
Child, <3 y	_-_ mmol/L (8.5-10.5 mg/dL)
Adult	_-_ mmol/L (9.0-10.1 mg/dL)

1.15-1.33

REFERENCE RANGES FOR CALCIUM (BISHOP)
Ionized Calcium–Serum
Adult	_-_ mmol/L (4.6-5.3 mg/dL)

1.15-1.27

REFERENCE RANGES FOR CALCIUM (BISHOP)
Ionized Calcium–Whole Blood
Adult	_-_ mmol/L (4.6-5.1 mg/dL

Primary Hypoparathyroidism

Primary Causes of Hypocalcemia

Vitamin D deficiency

Pseudohypoparathyroidism

Hypomagnesemia

Hypermagnesemia

Hypoalbuminemia (total only; ionized calcium not affected) – chronic liver disease, nephrotic syndrome, malnutrition

Acute pancreatitis

Renal disease

Rhabdomyolysis

Causes of Hypocalcemia

Neuromuscular irritability

Cardiac irregularities

Symptoms of Hypocalcemia (2)

Vitamin D

Calcium therapy

Treatment for Hypocalcemia (2)

Primary Hyperparathyroidism

Primary Cause of Hypercalcemia

Hyperthyroidism

Increased vitamin D

Benign familial hypocalciuria

Malignancy

Multiple myeloma

Milk alkali syndrome

Thiazide diuretics

Prolonged immobilization

Causes of Hypercalcemia

Mostly asymptomatic

Symptoms of Hypercalcemia

Neurological symptoms: Weakness, mild drowsiness, depression, lethargy, comatose

Severe Symptoms of Hypercalcemia

Serum

Plasma (lithium/ammonium heparin)

24-hour urine Ca2+

Specimen Collection

Specimen (3)

6 mol/L HCl

Specimen Collection

24-hour urine Ca2+ – acidified with _ _ _

1, 100

Specimen Collection

24-hour urine Ca2+ – acidified with 6 mol/L HCl

Add _ mL of HCl for each _ mL of urine

anaerobically

pH

Specimen Collection

According to Bishop, ionized Ca2+ must be collected _; as the _ increases, ionized Ca2+ decreases due to binding to proteins (albumin)

increase

decrease

anaerobically, normal

Specimen Collection

Hemolysis – false _

EDTA and oxalates – false _

Samples must be _ collected if ionized Ca2+ is the target; _ collection for total Ca2+

Atomic Absorption Spectrophotometry

Methods of Measurement

Reference method for total Ca2+

Orange

622 nm

Methods of Measurement

Atomic Absorption Spectrophotometry

Flame color:

Wavelength:

Liquid membrane

Methods of Measurement

Ion Selective Electrode

Clark and Collip

Methods of Measurement

Redox Titration Method

calcium oxalate

oxalic acid

potassium permanganate

Methods of Measurement

Clark and Collip

Measures serum calcium by precipitating calcium into _ _ converting it into _ _ and titrating it with _ _

Ferro and Ham

Methods of Measurement

Precipitation with chloranilic acid

Ortho-cresolphthalein complexone (CPC)

Methods of Measurement

Formation of colored complexes between calcium and the dye with absorbance of 578 nm

578 nm

Methods of Measurement

Ortho-cresolphthalein complexone (CPC)

Formation of colored complexes between calcium and the dye with absorbance of _ _

8-hydroxyquinolone

Methods of Measurement

Ortho-cresolphthalein complexone (CPC)

Uses _-_ to inhibit Mg (promotes chelation of Ca2+)

Colorimetric Endpoint (CPC)

Procedure

Method

albumin

blue-green

610 nm

Procedure

Principle:

Calcium is released from _ with a solvent and complexes with a dye forming a colored chromophore which is _-_ and is measured at _ _

8-hydroxyquinoline

Procedure

Principle:

The addition of _-_ to the reagent prevents the binding of magnesium

proportional

Procedure

Principle:

The absorbance of the colored complex is _ to the total calcium content of the serum

50 uL

PROCEDURE
Reagent	Standard	Sample
10 mg/dL	_

50 uL

PROCEDURE
Reagent	Standard	Sample
Sample		_

1,500 uL

1,500 uL

PROCEDURE
Reagent	Standard	Sample
Calcium Base Reagent	_	_

50 uL

50 uL

PROCEDURE
Reagent	Standard	Sample
Calcium Color Reagent	_	_

600 nm

1 minute

Procedure

Principle:

Mix well and read %T/absorbance of each tube at _ _ against water blank after _ _ in room temperature

10 mg/dL

Computation

Abs of the sample/Abs of the standard x _ _

0.25

Computation

Conversion to SI unit:

mg/dL x _ = mmol/L

8.5-11.0 mg/dL

2.13-2.75 mmol/L

REFERENCE RANGES FOR CALCIUM
	Conventional	SI Unit
Adult	_	_

10.0-11.5 mg/dL

2.50-2.88 mmol/L

REFERENCE RANGES FOR CALCIUM
	Conventional	SI Unit
Children	_	_

10.5-12.0 mg/dL

2.63-3.0 mmol/L

REFERENCE RANGES FOR CALCIUM
	Conventional	SI Unit
Infants	_	_

50.0-150.0 mg/dL

24

REFERENCE RANGES FOR CALCIUM
	Conventional	SI Unit
Urine Calcium	_ per _ hrs