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Flashcards in Magnesium and Calcium Deck (51):
0

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

Magnesium

1

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

1 mole (25grams) Magnesium

2

% of Magnesium found in the bone

53%

3

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

46%

4

% of Magnesium present in serum and Red blood cells

<1%

5

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

34%

6

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

61%

7

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

5%

8

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

Magnesium

9

Magnesium Serves as an essential cofactor of enzymes like:

-Amylase
-Acid Phosphatase
-Alkaline Phosphatase

10

Clinical significance of magnesium

-cardiovascular disorders
-metabolic disorders
-neuromuscular disorders

*others:
Hyperaldosteronism
Hyperparathyroidism
Hyperthyroidism
Hypercalcemia
Tubular disorder
Pyelonephritis
Glomerular mephritis

11

Sources of Magnesium:

Raw nuts
Dry cereals
Hard drinking water
Vegetables
Meat
Fish
Fruit

12

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

Small intestine

13

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

KIDNEY

14

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

Proximal Convoluted Tubule

15

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

Ascending Loop of Henle

16

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

Distal Convoluted Tubule

17

Renal threshold for Mg2+ is approx.

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

18

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

6%

19

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

Parathyroid Hormone (PTH)

20

These 2 hormones increases renal excretion of Mg2+

Aldosterone
thyroxine

21

Causes of hypomagnesemia

-reduced intake
-decreased absorption
-increased RENAL excretion
-increased ENDOCRINE excretion
-increased DRUG INDUCED excretion
-miscellaneous

22

Causes of Reduced intake of Magnesium

-poor diet
-prolonged magnesium deficient Intravenous(IV) therapy
-chronic alcoholism

23

Causes of decreased absorption of Mg2+

-malabsorption syndrome
-surgical resection of small intestine
-nasogastric suction
-pancreatitis
-prolonged vomiting and diarrhea
-Laxative abuse

24

Causes of increased Renal excretion

-tubular disorder
-glomerulonephritis
-pyelonephritis

25

Causes of Increased ENDOCRINE excretion

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

26

Causes of Increased DRUG INDUCED Excretion

-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

Miscellaneous causes of Hypomagnesemia

-excess Lactation: increased ise and loss thru milk production
-Pregnancy: hyperexcitable uteruS, anxiety and insomnia

28

Cardiovascular symptoms of Hypomagnesemia

Arrythmia
Hypertension
Digitalis roxicity

29

Psychiatric symptoms of. Hypomagnesemia

Depression
Agitation
Psychosis

30

Metabolic disorders causing hypomagnesemia

Hypocalcemia
Hypokalemia
Hyponatremia
Hypophosphatiemia

31

Treatment of Hypomagnesemia

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

32

In severe ill px, this is the preferred tx

Magnesium sulfate solution giver parenterally

33

Causes of Hypermagnesemia

-decreased secretion
-increased intake
-miscellaneous

34

Most common cause of hypermgnesemia

Renal failure

35

Decreased excretion of Mg2+ causes

Acute or chronic renal failure, and hyperthyroidism

Hypoaldosteronism and hypopituitarism( decreased GH and thyroxine)

36

Increased intake of these drugs leads to Hypermagnesemia

-antacids, enemas, catharics
-therapeutic-eclampsia, MI, cardiac arrythmias

37

Causes Pseudohypermagnesemia

Dehydration

38

Treatment of hypermagnesemia

-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

Specimen for det of Magnesium

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

40

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

Falsely Increased

41

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

Calcium shelter

42

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

Oxalate
Edta
Citrate

43

Positive result for mAgnesium in FES method

No color imparted to flame

44

Reference method for measuring Magnesium

AAS- Atomic absorption spectroscopy

45

3 most common colorimetric methods for Serum Magnesium measurement

Calmagit
Formazen
Methylthymol blue

46

Positive result for measurement of Mg2+ in calmagite methodq

Reddish violet compound @ 532 nm

47

Positive result for magnesium in Formazen dye method

Colored complex read @ 660 nm

48

Positive result for Magnesium in Methylthymol blue method

colored complex

49

Indicator used in Fluorometric Method for measuring magnesium

8-hydroxyquinoline indicator

50

Reference Range for serum Mg2+

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