Calcium, Magnesium, & Phosphorus pt. 2

Question 1

What are normal phosphorus levels

Answer 1

2.4 - 4.5 mg/dL

Question 2

What is the % of phosphorus in the bone compared to the blood?

Answer 2

85% in bone & 1% in blood

Question 3

What is the major role of phosphorus?

Answer 3

Bone formation

Question 4

List 5 other functions of phosphorus

Answer 4

1) Needed to make ATP
2) Metabolism of glucose, fats, & proteins
3) Helps excrete H+ ions in acid-base balance
4) Body controls balance through absorption & excretion loop
5) get it from diet & excrete via urine

Question 5

What is the difference between inorganic & organic phosphorus?

Answer 5

Inorganic → in the blood & what is measured
Organic → in the cells

Question 6

Phosphorus levels considered hypophosphatemia

Answer 6

Less than 2.5 mg/dL → considered severe when < 1 mg/dL

Question 7

List 8 causes of hypophosphatemia

Answer 7

1) Fluid shifts & losses thru kidneys
2) Prolonged antacid use
3) Corticosteroids, loop diuretics, increased Mg+ intake, excessive Alc intake, DKA
4) Increased glucose intake
5) TPN
6) Respiratory alkalosis
7) Low Vit. D levels
8) Malnourished or critically ill

Question 8

How do antacids cause hypophosphatemia & list 2 examples

Answer 8

Bind w phosphorus & increase excretion through stool
1) Ca++ carbonate (tums)
2) Aluminum

Question 9

How does increased glucose intake cause hypophosphatemia

Answer 9

Forces insulin & phosphorus out of the blood & into the cell

Question 10

How does TPN cause hypophosphatemia

Answer 10

There is NOT enough phosphorus & can cause phosphorus to go into the muscle

Question 11

List 6 Sx assoicated with hypophosphatemia

Answer 11

1) Decreased ATP production
2) Altered neural function
3) Altered musculoskeletal function
4) Blood disorder
5) Hypoxia to tissues
6) Mental fogginess, irritability

Question 12

Hypophosphatemia:

What happens due to altered musculoskeletal function?

Answer 12

Muscles get weak → pt on a ventilator will not be able to wean off even if they need to

Question 13

What is typical Tx for hypophosphatemia?

Answer 13

Oral supps → Potassium phosphate/ sodium phosphate (Neutra phos)

Question 14

What is the typical dose of oral potassium supplements for hypophosphatemia?

Answer 14

250-500 mg several times a day (weight based)
Levels checked 2-12 hrs after giving

Question 15

When might potassium supplements be given IV for hypophosphatemia?

Answer 15

Severe cases → usually under 1 mg/dL
Very irritating to the veins
Must be given slowly

Question 16

Phosphorus levels considered hyperphosphatemia

Answer 16

levels exceed 4.5 mg/dL

Question 17

Why does hyperphosphatemia occur?

Answer 17

Kidneys cannot excrete the phosphorus or extreme intake

Question 18

What is the most common cause of hyperphosphatemia?

Answer 18

Renal dysfunction

Question 19

List 2 other causes of hyperphosphatemia

Answer 19

1) Tissue injury → burns, heat stroke, low K+
2) Excess intake of phosphorus containing antacids & laxatives (help loosen stools)

Question 20

What almost ALWAYS accompanies hyperphosphatemia?

Answer 20

Hypocalcemia

Question 21

Clinical manifestations of hyperphosphatemia are related to ____

Answer 21

Hypocalcemia

Question 22

List 4 clinical manifestations of hyperphosphatemia

Answer 22

1) Chvostek’s sign
2) Trousseau’s sign
3) Cardiac irritability
4) Neuromuscular irritability

Question 23

List 3 things hyperphosphatemia can lead to

Answer 23

1) Bone disease
2) Hyperparathyroidism
3) Calcifications in tissues

Question 24

List 3 Tx options for hyperphosphatemia

Answer 24

1) Treat the cause!!
2) Dialysis if needed
3) Avoid phosphorus high foods

Question 25

List 11 foods high in phosphorus

Answer 25

1) Hard cheese 2) Cream 3) Nuts 4) Meats 5) Whole-grain cereals 6) Dried fruits 7) Dried vegetables 8) Kidney beans/ meat 9) Sardines 10) Sweetbreads (banana/ zucchini bread) 11) Foods made w milk

Question 26

What is the 2nd most abundant ICF cation after K+?

Answer 26

Magnesium

Question 27

Normal levels of magnesium

Answer 27

1.8 - 3.0 mg/dL

Question 28

List 4 things magnesium is needed for

Answer 28

1) Every step in DNA replication & transcription RNA 2) Create ATP (Na/K ATPase pump) action potential 3) Nerve conduction 4) K+ & Ca++ activity → esp. cardiac cells

Question 29

List 2 things we start to see without magnesium

Answer 29

1) Cardiac arrhythmias 2) Muscular dysfunction

Question 30

List 3 functions of magnesium

Answer 30

1) Peripheral vasodilation & affects peripheral resistance to bring BP down 2) Smooth muscle relaxant 3) Can Tx seizures (cerebral vasodilation)

Question 31

List 5 foods magnesium comes from

Answer 31

1) Grains 2) Nuts 3) Meats 4) Seafoods 5) Green vegetables

Question 32

Where is magnesium absorbed & excreted?

Answer 32

Absorbed in small intestine & excreted by the kidneys

Question 33

Where is most magnesium held?

Answer 33

In the kidneys → filters 6%

Question 34

Magnesium levels considered hypomagnesemia

Answer 34

Less than 1.8 mg/dL

Question 35

List 7 causes of hypomagnesemia

Answer 35

1) low intake or loss of Mg++ 2) Alcoholism 3) Poor nutrition/ calorie restriction 4) NG suction 5) Hypokalemia/ hypocalcemia 6) Metabolic acidosis 7) Diuretic use → washes everything out

Question 36

Since hypomagnesemia is usually r/t to low K+ & Ca++ what should we think?

Answer 36

Cardiac & neuro

Question 37

What is important to remember about hypokalemia in hypomagnesemia?

Answer 37

Hypomagnesemia increases hypokalemia & the hypokalemia will not respond to K+ replacement **MUST correct Mg+ first**

Question 38

List 5 Sx of hypomagnesemia

Answer 38

**All Sx of hypocalcemia** 1) Neuro irritability 2) Cardiac irritability → arrhythmias 3) Paresthesia 4) Chvostek's 5) Trousseau's

Question 39

What can long term hypomagnesmia lead to?

Answer 39

Osteoporosis

Question 40

Tx of mild hypomagnesemia

Answer 40

Corrected with diet or oral supplements → i.e. magnesium pills

Question 41

Tx of severe hypomagnesemia

Answer 41

IV replacement → magnesium sulfate must be given slowly (no more than 1-2 gm/ hr)

Question 42

What can happen if IV mag sulfate is given too fast?

Answer 42

It can cause life threatening arrhythmias

Question 43

Tx of hypomagnesemia can also cause ___

Answer 43

Diarrhea

Question 44

List 4 nursing care interventions for hypomagnesemia

Answer 44

1) Assess cardiac stability → heart rhythm, pulse, perfusion 2) Other electrolytes → K+ & Ca++ 3) Assess for dysphagia → increases risk of aspiration 4) Place on seizure precautions

Question 45

Possible test question: Which of the following electrolyte abnormalities does the nurse need to assess for/ put the patient on seizure precautions?

Answer 45

Sodium; Calcium; & Magnesium

Question 46

Magnesium levels considered hypermagnesemia

Answer 46

Levels exceed 3.0 mg/dL

Question 47

Why is hypermagnesemia considered rare?

Answer 47

The kidneys are usually able to handle the excretion

Question 48

What is the most common cause of hypermagnesemia?

Answer 48

Renal insufficiency

Question 49

List 2 other possible causes of hypermagnesemia

Answer 49

1) Too much magnesium containing laxatives/ antacids 2) Over Tx of pre-eclampsia

Question 50

List 5 clinical manifestations of hypermagnesemia

Answer 50

**Slows down everything** 1) Decreased DTRs 2) Muscle contractions 3) Bradycardia 4) Irritability 5) Depressed nerve function

Question 51

Tx of hypermagnesemia

Answer 51

Diuretics & NSS if kidneys are working

Question 52

How should hypermagnesemia be treated in someone with severe renal disease?

Answer 52

Treated w IV calcium gluconate → & dialysis for the kidney disease

Question 53

What should be avoided in patients with hypermagnesemia

Answer 53

ALL magnesium containing meds & IV solutions → i.e. LR

Question 54

List 2 nursing care interventions associated with hypermagnesemia

Answer 54

1) Assess for cardiac instability → hypotension due to vasodilation 2) Assess DTRs → decreased or absent

Question 55

Possible test question: What electrolyte imbalances can cause postural hypotension/ hypotension?

Answer 55

Hypermagnesemia & hypocalcemia

Question 56

List 2 things that always need to be monitored in a patient with pre-eclampsia

Answer 56

1) Neuro status 2) DTRs