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Clinical Laboratory > 13. Total and ionized Calcium | Total and ionized Magnesium > Flashcards

13. Total and ionized Calcium | Total and ionized Magnesium Flashcards

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1
Q

What are the 3 Forms of Calcium?

A
  1. Free / Ionized Calcium
  2. Complexed Calcium
  3. Plasma Protein-Bound Calcium
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2
Q

1| What is Free / Ionized Calcium?

A

Physiological ACTIVE Form

35 - 40% of Total Calcium Serum

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3
Q

2| What is Complexed Calcium?

A

Calcium that’s BOUND TIGHTLY to Variety of Anions

  • Bicarbonate; Lactate; Phosphate; Citrate

40 - 50% of Total Calcium Serum

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4
Q

3| What is Plasma Protein-Bound Calcium?

A

Associated with Albumin

80% of Total Calcium Serum

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5
Q

What Happens to the Levels of the Calcium Forms?

and Why?

A

Total Serum Calcium is UNCHANGED

Relative Distribution of 3 Forms is ONLY ALTERED

DUE to pH Changes in ECF

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6
Q

What are the General Functions of Calcium?

A

Skeletal Mineralisation

Blood Coagulation

Neural Transmission

Plasma Buffering Capacity

Enzyme Activity

Maintenance of Normal Muscle Tone

Excitability of Skeletal + Cardiac Muscle

Glandular Synthesis

Regulation of Exocrine / Endocrine Glands

Preservation of Cell Membrane = Integrity; Permeability

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7
Q

Where is Calcium Absorbed?

A

Duodenum

Upper Jejunum

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8
Q

When Does Calcium Absorption INCREASE?

A

Rapid Growth in Children

Pregnancy

Lactation

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9
Q

When Does Calcium Absorption DECREASED?

A

Advancing Age

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10
Q

What STIMULATES the Absorption of Calcium?

A

Vitamin D

Growth Hormone

Increased Dietary Protein

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11
Q

What MUST be the Ratio of Calcium : Phosphorus in the Intestinal Contents?

A

2 : 1

Calcium : Phosphorous

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12
Q

What Does INCREASED Ratio of Calcium : Phosphorus in the Intestinal Contents, Lead to?

A

Formation of INSOLUBLE Calcium Phosphates

  • INHIBITING Calcium Absorption
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13
Q

What Else INHIBITS Calcium Absorption?

A

Cortisol

EXCESSIVE Alkaline

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14
Q

How is the MAJORITY of Calcium LOST?

A

Urinary Excretion

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15
Q

What does the Plasma Concentration of Calcium Depend on?

A

Net Balance of Bone Mineral Deposition + Reabsorption

Intestinal Absorption

Renal Excretion

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16
Q

Which Hormones Regulate the Processes for Plasma Conc of Calcium?

A

Parathyroid Hormone, PTH

Calcitonin

1,25-Dihydroxyvitamin D

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17
Q

What are the Target Hormones for These Reg.Hormones?

A

Bone

Kidney

Intestine

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18
Q

What Happens when the Plasma Ionized Calcium Concentration DECREASES?

A

1) Parathyroid Glands Sense Change
2) Secrete PTH Immediately
3) PTH also acts on Kidney = Stimulate INCREASED Urine Phosphate Excretion + Calcium Reabsorption in Distal Nephron

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19
Q

What is the Role of Calcitonin?

A

Promotes Bone Growth

DECREASES Calcium Levels in Blood

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20
Q

What Can Affect Calcium Metabolism

that ARE NOT ASSOCIATED

with Plasma Changes in Calcium (and Phosphate)?

A

Thyroid Hormone

Growth Hormone

Adrenal Glucocorticoids

Gonadal Steroids

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21
Q

Which Forms of Calcium are Measured in Total Calcium Investigation?

A

Plasma Protein-Bound Calcium

Free / Ionized Calcium (ITSELF TOO!)

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22
Q

What are the Analytical Method for Total Calcium Investigation?

A
  1. Spectrophotometric Determination = OF Coloured Complex

2. Atomic Absorption Spectrophotometry

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23
Q

What is the Analytical Method for Free / Ionized Calcium Investigation?

Study These Flashcards
A

Ion-Selective Potentiometry

24
Q

What is the Reference Range of Total Calcium Serum?

Study These Flashcards
A

2.12 - 2.62 mmol / L

25
Which Specimen are Used for Total Calcium Investigation?
Serum Heparinized Plasma
26
What Can INTERFERE with Total Calcium Investigation?
Citrate; Oxalate; EDTA Hemolysis Icterus; Lipemia Paraproteins Magnesium
27
What is the Reference Range of Free / Ionized Calcium?
1.16 - 1.32 mmol / L
28
Which Specimen are Used for Free / Ionized Calcium Investigation?
Whole Blood Heparinized Plasma Serum
29
How Should Specimens for, Free / Ionized Calcium Investigation, be Transported?
Collected ANAEROBICALLY Transported on Ice + Stored at 4°C = TO PREVENT Loss of CO2 + Glycolysis; TO STABILISE pH
30
How does pH Changes Alter the Relative Distribution of Calcium Forms?
INCREASED pH = DECREASED Free / Ionized Calcium DECREASED pH = INCREASED Free / Ionized Calcium
31
What can Cause LOW pH Levels? and How?
Leaving Tourniquet on for TOO LONG! - This can INCREASE Value of Calcium Serum
32
What is the MOST COMMON Cause of HYPER-Calcemia (INCREASED Calcium Levels)?
Overproduction of PTH = Hyperparathyroidism
33
What Can Confirm the INCREASE of Calcium, in Urine?
24Hr Urine Examination
34
What Genetic Factor Causes INCREASED Calcium Levels?
Hypocalciuric Hypercalcemia - Where Individuals DO NOT Excrete Normal Amounts - HENCE INCREASED Levels of Calcium in Serum
35
What are the Other Causes of INCREASED Calcium Levels?
EXCESSIVE Vitamin D Immobilization Kidney Failure Hyperthyroidism Medications = Thiazide Diuretics
36
What are the Symptoms of HYPO-Calcemia (DECREASED Calcium Levels)?
Weakness Muscle Spasms Heart Rhythm Disturbance GI Disorders Impaired Growth = In Children
37
How Much of Total Magnesium is in Extracellular Fluid?
1%
38
How Much Magnesium is Ionized / Free Magnesium?
55%
39
How Much Magnesium is Plasma Protein-Bound Magnesium?
30% Associated with Albumin
40
How Much Magnesium is Complex Magnesium?
15% WITH - Phosphate - Citrate - Other Anions
41
How Much of Total Magnesium is in Intracellular Fluid or Bone Matrix?
99% 60% = Bone Matrix 40% = Skeletal Muscles, Blood Cells, Other Cells
42
What is the General Function of Magnesium?
Essential for MORE than 300 Cellular Enzymes - Transfer of Phosphate Groups; - Require ATP: - Transcription + Translation of DNA ------------------------------ Membrane Stabilisation Nerve Conduction Ion Transport Calcium Channel Activity
43
How is Magnesium Regulated?
GI Absorption Renal Excretion
44
What is the MAJOR Regulator of Magnesium?
Plasma Mg2+
45
What Happens in Magnesium DEFICIENCY?
1) LEADS to REDUCED Urinary Excretion 2) Prolongs Bone Storage of Mg ---------------------------- Plasma Electrolyte Abnormalities Cardiac Arrhythmias
46
Which Specimen are Used for Total Magnesium Investigation?
Serum NOT Plasma
47
Why is Plasma an UNACCEPTABLE Specimen for Total Magnesium Investigation?
Anticoagulant in Plasma INTEFERES with Most Procedures
48
What Analytical Method is Used for Total Magnesium Investigation?
Photometry = Absorbance of 520 nm
49
What is the Reference Method for Total Magnesium Investigation?
Atomic Absorption Spectrophotometry
50
How is Free / Ionized Magnesium Measured?
Magnesium Ion-Selective Electrodes, ISE
51
How does pH Changes Alter the Relative Distribution of Magnesium Forms?
INCREASED pH = DECREASED Free / Ionized Magnesium DECREASED pH = INCREASED Free / Ionized Magnesium
52
What is the Reference Range of Total Magnesium Serum?
0.75 - 0.95 mmol / L
53
What is the Reference Range of Free / Ionized Magnesium ?
0.44 - 0.6 mmol / L
54
What Conditions are Associated with HYPER-Magnesemia? (INCREASED Magnesium Levels)?
Impaired Kidney Function Diabetic Ketoacidosis Adrenal Insufficiency Hyperparathyroidism Hypocalcaemia (LOW Calcium Levels) Hyperkalemia (HIGH Potassium Levels)
55
What are the Symptoms of HYPER-Magnesemia? (INCREASED Magnesium Levels)?
Heart Rhythm Disturbances Muscle Weaknesses Nausea + Vomiting Breathing Difficulties
56
What Conditions are Associated with HYPO-Magnesemia? (DECREASED Magnesium Levels)?
Dietary Deficiencies / Malnutrition Absorption Insufficiency Increased Excretion Alcoholism Diarrhoea Medical Diuretics
57
What are the Symptoms of HYPO-Magnesemia? (DECREASED Magnesium Levels)?
Heart Rhythm Abnormalities Muscle Weakness + Cramps Confusion; Hallucination; Seizures

Clinical Laboratory (31 decks)

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