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Clinical Chemistry 2 > Magnesium and Calcium > Flashcards

Magnesium and Calcium Flashcards

0
Q

The averge human body(70kg) contain how many moles of Mg2+?

A

1 mole (25grams) Magnesium

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1
Q

4th most abundant cation in the body and 2nd most abundant cellular ion

A

Magnesium

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2
Q

% of Magnesium found in the bone

A

53%

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3
Q

% of Magnesium found in muscle and other organs and soft tissue

A

46%

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4
Q

% of Magnesium present in serum and Red blood cells

A

<1%

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5
Q

In the serum, about ___% magnesium is bound to protein, primarily albumin

A

34%

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6
Q

In the serum, about ___% magnesium exists in the free or ionized state(active)

A

61%

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7
Q

In the serum, about ___% magnesium is complexed with other ions (phosphate, citrate)

A

5%

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8
Q

It is the free ion that is physiologically activite in the body

A

Magnesium

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9
Q

Magnesium Serves as an essential cofactor of enzymes like:

A
  • Amylase
  • Acid Phosphatase
  • Alkaline Phosphatase
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10
Q

Clinical significance of magnesium

A
  • cardiovascular disorders
  • metabolic disorders
  • neuromuscular disorders
*others:
Hyperaldosteronism
Hyperparathyroidism
Hyperthyroidism
Hypercalcemia
Tubular disorder
Pyelonephritis
Glomerular mephritis
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11
Q

Sources of Magnesium:

A 
Raw nuts
Dry cereals
Hard drinking water
Vegetables 
Meat 
Fish
Fruit
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12
Q

The ___ ______ may absorb 20-65% of the dietary Magnesium depending on the need and intake

A

Small intestine

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13
Q

This largely controls the overall Magnesium in the body and also reabsorbs Magnesium in deficiency states or readily excrete excess Mg2+ in overload states

A

KIDNEY

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14
Q

25-35% of the nonprotein-bound Magnesium (that gets filtered by glomerulus) is reabsorbed by the:

A

Proximal Convoluted Tubule

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15
Q

This is the major regulatory site where 50-60% of filtered Mg2+ is reabsorbed in the:

A

Ascending Loop of Henle

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16
Q

2-5% of the filtered Mg2+ is reabsorbed in the

A

Distal Convoluted Tubule

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17
Q

Renal threshold for Mg2+ is approx.

A

0.60-0.85 mmol/L (=1.46-2.07 mg/dl)

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18
Q

Normally, only about _% of filtered Mg2+ is excreted in urine per day

A

6%

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19
Q

This hormone increases the renal reabsorption of Mg2+ in the intestine

A

Parathyroid Hormone (PTH)

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20
Q

These 2 hormones increases renal excretion of Mg2+

A

Aldosterone

thyroxine

21
Q

Causes of hypomagnesemia

A
  • reduced intake
  • decreased absorption
  • increased RENAL excretion
  • increased ENDOCRINE excretion
  • increased DRUG INDUCED excretion
  • miscellaneous
22
Q

Causes of Reduced intake of Magnesium

A
  • poor diet
  • prolonged magnesium deficient Intravenous(IV) therapy
  • chronic alcoholism
23
Q

Causes of decreased absorption of Mg2+

A
  • malabsorption syndrome
  • surgical resection of small intestine
  • nasogastric suction
  • pancreatitis
  • prolonged vomiting and diarrhea
  • Laxative abuse
24
Q

Causes of increased Renal excretion

A
  • tubular disorder
  • glomerulonephritis
  • pyelonephritis
25
Q

Causes of Increased ENDOCRINE excretion

A
  • hyperparathyroidism
  • hypercalcemia
  • hyperaldosteronism (causes paeudohypomagnesia due to increased water reabsorption)
  • Hyperparathyroidism
  • Diabetic Ketoacidosis (excess urinary loss of Mg associated with Glycosuria)
26
Q

Causes of Increased DRUG INDUCED Excretion

A
  • dirutecs: Loop diiretics like FUROSEMIDE (increases renal loss of Mg2+)
  • thiazide diuretics: require a longer period of use to cause hypomagnesemia
  • Antibiotics (gentamicin, cisplatin)
  • Cyclosporine: nephrotoxixity, hypertension & neurologic symptoms
  • Cardiac Glycosides: digitalis and digoxin
27
Q

Miscellaneous causes of Hypomagnesemia

A
  • excess Lactation: increased ise and loss thru milk production
  • Pregnancy: hyperexcitable uteruS, anxiety and insomnia
28
Q

Cardiovascular symptoms of Hypomagnesemia

A

Arrythmia
Hypertension
Digitalis roxicity

29
Q

Psychiatric symptoms of. Hypomagnesemia

A

Depression
Agitation
Psychosis

30
Q

Metabolic disorders causing hypomagnesemia

A

Hypocalcemia
Hypokalemia
Hyponatremia
Hypophosphatiemia

31
Q

Treatment of Hypomagnesemia

A

-oral intake of Magnesium lactate, Magnesium oxide, magnesium chloride or an antacid that contains Magnesium

32
Q

In severe ill px, this is the preferred tx

A

Magnesium sulfate solution giver parenterally

33
Q

Causes of Hypermagnesemia

A
  • decreased secretion
  • increased intake
  • miscellaneous
34
Q

Most common cause of hypermgnesemia

A

Renal failure

35
Q

Decreased excretion of Mg2+ causes

A

Acute or chronic renal failure, and hyperthyroidism

Hypoaldosteronism and hypopituitarism( decreased GH and thyroxine)

36
Q

Increased intake of these drugs leads to Hypermagnesemia

A
  • antacids, enemas, catharics

- therapeutic-eclampsia, MI, cardiac arrythmias

37
Q

Causes Pseudohypermagnesemia

A

Dehydration

38
Q

Treatment of hypermagnesemia

A
  • discontinue Mg2+ source
  • for severe Hypermagnesemia: immediate supportive therapy for cardiac, neuromuscular or respiratory abnormalities
  • for patients with Renal failure: dialysis
  • for normal renal dunction: Diuretic and IV fluid
39
Q

Specimen for det of Magnesium

A

Serum (nonhemolyzed)
Plasma (anticoag: Lithium heparin)
Urine (24hrs)

40
Q

Hemolysis causes falsely ____ Magnesium since Mg is 10x Grater in the intracellular fluid than in Extracellular

A

Falsely Increased

41
Q

This is added to remove the presence of Calcium during determination of Magnesium

A

Calcium shelter

42
Q

Unacceptable anticoags for determination of mg2+ because theyll bind to Mg2+

A

Oxalate
Edta
Citrate

43
Q

Positive result for mAgnesium in FES method

A

No color imparted to flame

44
Q

Reference method for measuring Magnesium

A

AAS- Atomic absorption spectroscopy

45
Q

3 most common colorimetric methods for Serum Magnesium measurement

A

Calmagit
Formazen
Methylthymol blue

46
Q

Positive result for measurement of Mg2+ in calmagite methodq

A

Reddish violet compound @ 532 nm

47
Q

Positive result for magnesium in Formazen dye method

A

Colored complex read @ 660 nm

48
Q

Positive result for Magnesium in Methylthymol blue method

A

colored complex

49
Q

Indicator used in Fluorometric Method for measuring magnesium

A

8-hydroxyquinoline indicator

50
Q

Reference Range for serum Mg2+

A

Serum, colorimetric: 0.63-1.0 mmol/L (1.26-2.10 mEq/L)

Clinical Chemistry 2 (11 decks)

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