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(UNI) Clinical (2nd Year) > Electrolyte Disturbances > Flashcards

Electrolyte Disturbances Flashcards

1
Q

Define hypokalaemia.

A

Plasma potassium levels < 3.0 mmol/L.

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2
Q

Which organ usually controls plasma potassium levels?

A

The liver.

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3
Q

What is ones normal dietary intake of potassioum?

A

50 mmol/day.

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4
Q

How should hypokalaemia be treated?

A

Potassium supplements (effervescent or slow release), replace thiazide or loop diuretics with potassium sparing diuretics.

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5
Q

Should scientific terms regarding electrolyte imbalances be used when talking to patients? Why?

A

No because it may confuse them and make them more worried than they need to be.

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6
Q

How is excess sodium excreted?

A

In the urine.

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7
Q

What percentage of the bodies sodium is freely exchangeable?

A

70%.

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8
Q

In the western world, how much sodium is taken in in the diet?

A

10-20x the normal requirement.

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9
Q

In mild cases of hyponatraemia, what symptoms do patients show?

A

None, at this stage it is asymptomatic.

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10
Q

What is the mortality in patients with 120-125 mmol/L sodium?

A

25%.

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11
Q

What is the mortality of patients with less than 120 mmol/L?

A

50%.

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12
Q

If serum sodium levels are less than 125mmol/L (mild), what symptoms may a patient experience?

A

Occasional headaches, confusion, vomiting. Especially if levels rapidly fall.

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13
Q

If serum sodium levels are between 120-125 mmol/L (moderate), what symptoms may a patient experience?

A

Confusion, lethargy, muscle cramps, N&V, unsteady gait.

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14
Q

If serum sodium levels are between 115-120 mmol/L (moderate plus), what symptoms may a patient experience?

A

Drowsiness and agitation.

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15
Q

If serum sodium levels fall bellow 115 mmol/L (severe), what symptoms may a patient experience?

A

Seizures, respiratory depression, coma.

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16
Q

What causes the CNS symptoms seen in hyponatraemia?

A

Movement of water in neuronal cells.

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17
Q

Why cant acute cases of hyponatraemia be treated too quickly?

A

Brain cells/neuronal cells may become damaged through being shrunk.

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18
Q

By what amount should serum sodium levels not be raised faster than?

A

0.5 mmol/L/hour.

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19
Q

How should serum sodium levels be corrected in a patient with hyponatraemia?

A

This is achieved by either giving IV fluids containing sodium or via fluid restriction and diuretics. The method used depends on the fluid status of the patient.

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20
Q

When is emergency treatment for hyponatraemia needed?

A

Emergency treatment is needed if the condition is symptomatic and shows rapid onset.

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21
Q

Describe emergency treatment of hyponatraemia.

A

Hypertonic saline (3%) is used to restore serum sodium concentration to a safe level (usually greater than 120 mmol/L). Then consider the cause of the condition and treat accordingly.

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22
Q

What causes hypernatraemia?

A

This is usually due to water deficit rather than sodium deficit. Can be caused by anabolic steroids and oral contraceptives.

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23
Q

What are the signs and symptoms of hypernatraemia?

A

Signs of this condition include muscle weakness and confusion. In a normal body, if waster loss is high a person can become unconscious and experience a high fever. If the water is not replaced the patient can suffer from diabetes insipidus.

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24
Q

What is diabetes insipidus?

A

Diabetes insipidus is when a patient has very dilute urine due to a lack of ADH or a lack of response to ADH. It can be drug induced, by drugs such as lithium or phenytoin.

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25
Q

How is hypernatraemia treated?

A

The cause of the condition must be treated. The problem must be corrected slowly, slowly replacing the water deficit, dextrose IV is used. The choice of fluid used will depend on whether on the patient’s fluid state.

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26
Q

Is serum potassium a good indicator of total bodily potassium? Why?

A

No, because only 2% of potassium is present in ECF. It is primarily an intracellular electrolyte.

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27
Q

How is potassium balance maintained?

A

Balance us maintained by fine control from the kidneys, with a limited role played by the GI tract. Some potassium is also lost through sweat.

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28
Q

How does insulin affect potassium?

A

Insulin drives potassium into cells.

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29
Q

What is usually the cause of low serum potassium levels?

A

Lowered serum potassium levels are usually due to the movement of potassium into cells due to the action of drugs such as insulin or salbutamol.
Hypokalaemia can also be caused by an increase in potassium excretion, usually down to diuretics. Damage to neurones can also lead to potassium loss.

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30
Q

How can potassium levels affect some anti-arrhythmic drugs, such as digoxin?

A

Digoxin toxicity can be caused by potassium levels.

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31
Q

Hypokalaemia is usually asymptomatic however, what symptoms may sometimes be seen?

A

Severe vomiting, diarrhoea, muscle weakness, tiredness, constipation, confusion, cardiac arrhythmias.

32
Q

When should hypokalaemia be treated urgently?

A

When levels are less than 2.5 mmol/L.

33
Q

What does each 0.3 mmol/L reduction in serum potassium represent?

A

100 mmol/L deficit in body stores.

34
Q

What medicinal forms shouldn’t be used to replace potassium in a patient?

A

Modified release, liquid, effervescent.

35
Q

What is the dosage range for the treatment of hypokalaemia?

A

40-120 mmol per day.

36
Q

What foods can be used as a replacement to medication to treat hypokalaemia?

A

Tomatoes, mangoes, potatoes.

37
Q

What causes refractory hypokalaemia?

A

Hypomagnesaemia.

38
Q

What usually causes hyperkalaemia?

A

Kidney problems. Rarely excessive intake. Potassium sparing diuretics.

39
Q

How can poor experimental/lab technique lead to false plasma potassium readings?

A

One should be aware that poor experimental/lab technique can cause the red blood cells in the sample to lyse, this will release intracellular potassium and give a false reading for the plasma potassium concentration.

40
Q

Hyperkalaemia is often asymptomatic, however it can be fatal. What other symptoms can also be seen as a cause of hyperkalaemia?

A

The main symptoms seen are cardiac, such as cardiac arrhythmias and eventually sudden cardiac death if levels get high enough.

41
Q

What plasma potassium levels, when surpassed, gives reason for the patient to be treated urgently? Why must this be treated urgently?

A

If plasma potassium concentrations go above 6.5 mmol/L, the patient must be treated urgently, and this is treated as a medical emergency as the patient can go into cardiac arrest.

42
Q

If a patient is experiencing mild to moderate hyperkalaemia with no ECG changes, how should they be treated?

A

Remove potassium from the body with an ion-exchange resin, e.g. calcium or sodium polystyrene sulfonate.

43
Q

What are ion exchange resins (used to treat hyperkalaemia)?

A

These are an insoluble matrix that is porous and traps ions. This binds potassium in the colon.

44
Q

How should ion exchange resins (used to treat hyperkalaemia) be used?

A

This should be given by mouth with lactulose (not mixed with fruit juice, water only) or as an enema.

45
Q

What is the onset of action of ion exchange resins (used to treat hyperkalaemia)?

A

The onset of action is slow, taking over 2 hours.

46
Q

How should a patient with severe hyperkalaemia (potassium > 6.5 mmol/L) or who has experienced ECG changes, be treated?

A

The cardiac membrane should be protected with 10-20ml of calcium gluconate 10% by slow IV injection that lasts 30 mins.
Potassium should be shifted into cells with insulin and glucose.
In extreme cases, haemodialysis can be considered.

47
Q

How should insulin be used to treat severe hyperkalaemia?

A

5-10 units of soluble insulin in 50ml glucose over 30 minutes. The patients U&Es should be checked after 30 minutes and then after 2 hours if good response. The infusion should begin to work in 15 minutes.

48
Q

What is a bone screen test?

A

. This test tests for calcium, phosphate, alkaline phosphatase, and albumin levels in the blood.

49
Q

How much calcium is there, roughly, in a 70kg man?

A

1kg.

50
Q

As well as being important in bone structure, what else is calcium important for?

A

Calcium is also important in the neuromuscular system, in signalling, and as a co-enzyme.

51
Q

In what three forms is calcium found in plasma?

A

Bound to protein (albumin), complexed with citrus and phosphate, and free ions.

52
Q

What can cause hypocalcaemia?

A
  • Hypoalbuminaemia.
  • Vit D deficiency.
  • Impaired metabolism of vit D.
  • Renal failure.
  • Hypoparathyroidism.
  • Hypomagnasaemia.
53
Q

If hypocalcaemia is mild, there may not be any symptoms. However, what symptoms may be seen?

A

Symptoms can include neural conditions, muscular excitability, cramps, convulsions, anxiety, irritability, and can be life threatening.

54
Q

How can mild hypocalcaemia be treated?

A

If the condition is mild, it should be treated with oral supplements (calcium carbonate) and dietary changes.

55
Q

How should severe acute hypocalcaemia be treated?

A

Calcium gluconate IV should be administered slowly over 5 minutes whilst the patient is monitored via ECG.

56
Q

Which two conditions account for nearly 90% of hypercalcaemia cases?

A

Malignancy (bone metastesis) and hyperparathyroidism.

57
Q

When hypercalcaemia symptoms present, they often present rapidly, and the patient becomes violently ill. What may symptoms me include?

A

Symptoms include polyurea (excessive urination), polydipsia (excessive thirst), lethargy, nausea, and many more.

58
Q

What can extremely high levels of calcium (> 3.5 mmol/L) lead to?

A

Dysrhythmia and coma.

59
Q

If calcium levels are < 3.0 mmol/L, the patient will often be asymptomatic. Will they need urgent correction?

A

No.

60
Q

If the patients calcium levels are > 3.5 mmol/L, does the patient require urgent attention? Why?

A

Yes. Because there is the risk of dysrhythmia and coma.

61
Q

How is acute hypercalcaemia treated?

A

For acute hypercalcaemia, re-hydrate the patient with IV 0.9% NaCl to increase the output of calcium (4-6L over 24 hours). The patient may need dialysis if they have severe renal failure as they can’t be given too much fluid. After the patient is re-hydrated, IV bisphosphate is given to reduce bile turnover.

62
Q

Which ion does phosphate have an inverse relationship with?

A

Calcium.

63
Q

Low levels of phosphate are common, how can they be treated?

A

Low levels of phosphate are common and can be corrected with oral or IV treatment.

64
Q

In what conditions can an increase in serum alkaline phosphate be seen?

A

Liver and bone conditions.

65
Q

Why do children exhibit increased levels of alkaline phosphate?

A

Due to their constant growth.

66
Q

Where is albumin produced?

A

In the liver.

67
Q

What ions does albumin bind?

A

Calcium and phosphate.

68
Q

The blood concentration of albumin changes in which condition?

A

Liver damage.

69
Q

Is magnesium primarily intra- or extracellular?

A

Intracellular.

70
Q

What other electrolyte disturbances in hypomagnasaemia often associated with?

A

It is often associated with hypokalaemia and hypocalcaemia.

71
Q

What is one of the main symptoms of hypomagnasaemia?

A

Neuromuscular conditions.

72
Q

What is one of the main causes of hypomagnasaemia?

A

Drugs.

73
Q

When should hypomagnasaemia be treated?

A

Treat if ≤ 0.4 mmol/L, or > 0.4 mmol/L if symptomatic.

74
Q

How can hypomagnasaemia be treated?

A

Treatment is achieved with oral magnesium however this unlicensed. If the condition is more extreme, IV magnesium sulphate can be used. This is given over 3 hours, longer if malabsorption.

75
Q

List common symptoms of hypermagnesaemia.

A

Common symptoms of hypermagnesemia are hypertension, respiratory depression, and cardiac arrest at the more severe end.

76
Q

What is given to treat hypermagnesaemia?

A

Loop diuretics are given to treat hypermagnesemia.

(UNI) Clinical (2nd Year) (19 decks)

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