Monitoring Drug Therapy 1 Urea and electrolytes

Question 1

why should patients be monitored?

Answer 1

1) aid diagnosis
2) severity of disease
3) effectiveness of treatment: response to treatment, dose adjustments identified based on results
4) ADR’s: Renal/ hepatic function, Therapeutic drug monitoring (TDM)

Question 2

what can be monitored using blood tests?

Answer 2

1) Urea and Electrolytes
2) Haematology
3) Renal function
4) Liver function
5) Cardiac enzymes
6) TDM

Question 3

list the different clinical observations that are measured

Answer 3

1) BP, pulse
2) Oxygen saturations
3) Respiratory rate
4) Urine output, fluid balance, daily weights
5) Pain score
6) Blood glucose

Question 4

why are urea and electrolytes measured?

Answer 4

Urea and electrolytes most common test they help indicate:

1) Renal function
2) Hydration status
3) Assess disease status
4) Identify possible ADRs
5) volume of blood and its pH.
- Creatinine levels are a major factor in determining the estimated glomerular filtration rate.

Question 5

what is the normal blood sodium level and what can abnormal sodium levels lead to?

Answer 5

1) Sodium (Na+) 133 -146mmol/L
2) Abnormal levels usual reflect water loss/imbalance rather than sodium loss/gain
3) Major Extracellular cation: Regulated by aldosterone (RAAS system)

Question 6

what can the levels of sodium in the blood directly affect?

Answer 6

blood pressure:

1) low levels of sodium can cause hypotension
2) conversely large intakes of salt from diet can cause hypertension.

Question 7

which system regulates the amount of sodium in the body?

Answer 7

1) the renin–angiotensin–aldosterone system (RAAS) is a hormone system that regulates blood pressure and fluid balance.
2) Angiotensinogen from the liver gets converted to Angiotensin I by renin secreted by the kidneys
3) Angiotensin I gets converted to Angiotensin II by ACE
4) Angiotensin II stimulates the Adrenal Cortex to produce Aldosterone
5) Aldosterone has a number of different action:
Na+ Reabsorption, H2O Reabsorption, K+ Excretion
6) Aldosterone’s actions result in a net increase in blood volume, Increased blood volume inhibits production of Angiotensin II via negative feedback.

Question 8

what is Hypernatraemia and what are the causes?

Answer 8

1) Hypernatraemia (Na+ >146mmol/L)
2) Insufficient fluid intake
3) Excessive water loss
4) Sodium retention/too much sodium from diet
5) Excess adrenocorticoid hormones e.g. Cushings syndrome
6) Pharmacological - e.g. corticosteroids, NSAIDs and Lithium toxicity

Question 9

what are the Consequences of Hypernatraemia?

Answer 9

1) CNS changes from lethargy/stupor to deep coma
2) Dependant on level >170mmol/l life-threatening
3) Symptoms may include: fever, tachycardia, hypertension, dizziness, increased thirst, oedema.

Question 10

what is Hyponatraemia and what are the causes?

Answer 10

1) Hyponatraemia (Na+

Question 11

what are the symptoms of Hyponatraemia?

Answer 11

1) Headache
2) Nausea, Vomiting
3) Cramps
4) Circulatory failure
5) Confusion
6) Convulsions
7) Postural hypotension
8) Fatigue

Question 12

what is the treatment for Hyponatraemia?

Answer 12

1) Avoid Rapid Correction (osmosis)
2) Hypovolaemic hyponatraemia (Inadequate intake of free water associated with total body sodium depletion): Replacement with IV NaCl 0.9%
3) Euvolaemic hyponatraemia (Excessive excretion of water from the kidneys) : Treat any immediate cause, e.g hormone replacement. If not feasible, water restriction is recommended.
- Fluid restriction failed/unresponsive - consider Demeclocycline
4) Symptomatic patients may need hypertonic (3%) saline infusion
5) Hypervolaemic hyponatraemia ( elevated jugular venous pressure and peripheral oedema) is corrected with fluid restriction, diuretics and sodium restriction
Chronic conditions with mild/moderate sodium depletion oral supplements can be used.

Question 13

what is the normal level of potassium in the body and what is the function of potassium ?

Answer 13

1) Potassium (K+) 3.5 - 5.3mmol/L
2) Largely intracellular Needs usually met from dietary sources
3) Essential for maintaining muscle contractility, e.g. cardiac muscle
4) Maintains fluid balance, nerve impulse function and muscle function.
- Relationship between movement of sodium and potassium is governed by Na/K ATPase pump.

Question 14

what is Hyperkalaemia and what are the causes?

Answer 14

1) Hyperkalaemia (K+>5.3mmol/L)#
2) Renal failure
3) Metabolic acidosis
4) K+ retaining diuretics
5) K+ supplements
6) ACE inhibitors, Angiotensin II receptor blockers, NSAIDs
7) Heparin
8) Beta blockers (non-selective)
9) Trimethoprim

Question 15

very high levels of potassium can lead to Cardiac toxicity (>6 mmol/l). list the side effects of cardiac toxicity

Answer 15

1) Arrhythmia
2) Tachycardia
3) Ventricular fibrillation
4) Asystole

Question 16

what is the treatment for Hyperkalaemia?

Answer 16

1) Stop offending medication
2) Restrict potassium intake
3) IV calcium gluconate 10%
4) Infusion of insulin + glucose
5) Ion exchange resins e.g. calcium resonium
6) Mild: loop or thiazide to enhance renal excretion providing RF is adequate

Question 17

what is Hypokalaemia and what are the causes?

Answer 17

1) Hypokalaemia (K+

Question 18

what are the symptoms of Hypokalaemia?

Answer 18

1) Muscular weakness
2) Tetany
3) Respiratory failure
4) Paralysis
5) Cardiac arrhythmias
6) Sudden death

Question 19

what is the treatment for hypokalaemia

Answer 19

1) Potassium effervescent tablets (sando-K®)
2) Intravenous potassium (usually mixed with glucose or sodium chloride) at 20 - 40mmol/Litre
3) Bananas!

Question 20

Hyponatremia is classified according to volume status. list the 3 types of hyponatremia

Answer 20

1) Hypovolemic hyponatremia: decrease in total body water with greater decrease in total body sodium
2) Euvolemic hyponatremia: normal body sodium with increase in total body water
3) Hypervolemic hyponatremia: increase in total body sodium with greater increase in total body water

Question 21

what is the the normal concentration of calcium in the body and why do we need calcium?

Answer 21

1) Calcium 2.12-2.65 mmol/L
2) Structural element in bones and teeth
3) Cofactor for enzymes and proteins
4) Mediates vasoconstriction/dilation, nerve impulse transmission, muscle contraction and secretion of hormones (insulin)

Question 22

list the Main hormones involved in calcium homeostasis

Answer 22

1) Parathyroid hormone
2) Vitamin D metabolites (Calcifedol and Calcitriol)
3) Calcitonin
- calcium Levels affected by high or low albumin concentration. 40 - 50% is bound to plasma proteins. Only free calcium is active

Question 23

what is Hypercalcaemia and what are the causes?

Answer 23

1) Hypercalcaemia = decreased serum PTH and increased serum calcitonin.
- Stops calcium from being absorbed by the GI tract, decreases bone resorption and increases calcium excretion from the kidneys.
2) Malignancies
3) Hyperparathyroidism
4) Dehydration
5) Pharmacological- E.g. antacids, calcium salts, thiazides and androgens, levothyroxine, lithium, excess vitamin d

Question 24

what are the symptoms, and what are the implications of long term hypercalaemia?

Answer 24

1) GI disturbances: Anorexia, Nausea/vomiting, Constipation
2) Mental symptoms: fatigue, depression, psychosis
3) Headaches and generalised muscle weakness
4) Polyuria and increased thirst
5) Implications of long term hypercalcaemia include developing gallstones, reduced renal function, coma and death.

Question 25

what is the treatment for hypercalaemia?

Answer 25

1) Review/discontinue drugs promoting hypercalcaemia (thiazides, vitamin D analogues, calcium supplements) and correct dehydration.
2) Bisphosphonates
3) Steroids
4) Cinacalcet (for renal dialysis patients with parathyroid dysfunction)

Question 26

what is Hypocalcaemia and what are the causes?

Answer 26

1) Increased serum PTH and decreased serum calcitonin.
- Encourages increased GI absorption of calcium, increased bone resorption, and decreased renal calcium excretion.
2) Hypoparathyroidism
3) Malnutrition
3) Renal failure
4) Pharmacological (loops, bisphosphonates)
5) Inadequate vitamin d production/action

Question 27

what are the symptoms of Hypocalcaemia?

Answer 27

1) Tends to be asymptomatic if hypocalcaemia is mild.

2) In severe cases – paraesthesia of face, tetany (muscle spasms), convulsions and paralysis.

Question 28

what is the treatment for hypocalcaemia?

Answer 28

Calcium Gluconate 10% (10-20ml) as a slow bolus (+ ECG)

Question 29

what is the normal level of phosphate in the body and what is the role of phosphate?

Answer 29

1) Phosphate 0.8-1.4mmol/L
2) Phosphate is acquired through diet
3) Low levels can be implicated in development of rickets where vitamin D levels are low.
4) Regulate acid/base balance

Question 30

what are the symptoms of Hypophosphataemia?

Answer 30

1) Muscle weakness
2) Confusion
3) Respiratory difficulties

Question 31

what are the causes of Hypophosphataemia?

Answer 31

1) Inadequate intake : Malnourished patients,
Interference with absorption (e.g. antacids binding phosphate, disease process – Crohn’s disease)
2) Excessive loss: Diuresis, Dialysis, Alcoholism
3) Redistribution into cells

Question 32

what is the treatment for Hypophosphataemia?

Answer 32

1) Oral phosphate (Phosphate Sandoz®, 4-6 tablets daily)
2) Intravenous phosphate
3) Monitoring of other electrolytes is essential, as calcium and potassium can be affected.
- May need to supplement calcium too especially if patient is hypocalcaemic.

Question 33

what are the causes of Hyperphosphataemia?

Answer 33

1) Renal impairment. Accumulation of phosphate is common due to inability to excrete it
2) Vitamin D excess
3) Hypoparathyroidism
4) Acromegaly

Question 34

what is the treatment for Hyperphosphataemia?

Answer 34

1) Phosphate intake from the diet can be minimised using ‘phosphate binders’
- Taken at mealtimes to remove dietary phosphate
- Examples: Calcium carbonate, aluminium hydroxide and Sevelamer.

Question 35

what is the normal level of magnesium found in the body and what is the purpose of magnesium?

Answer 35

1) Magnesium (0.7-1 mmol/L)
2) Essential for nerve and muscle function
3) Activates cellular enzymatic activity, particularly metabolism

Question 36

what are the symptoms of Hypomagnesaemia?

Answer 36

Neuromuscular irritability (tetany, epilepsy), CV signs (tachycardia, ECG changes)

Question 37

what are the causes of Hypomagnesaemia?

Answer 37

1) Abnormal losses from gastro-intestinal tract
2) Inadequate dietary intake
3) Chronic Alcoholism
4) Accompanying hypokalaemia/hypocalcaemia
5) Pharmacological: Aminoglycoside antibiotics, Bisphosphonates, Immunosuppressants, Prolonged diuretic therapy ( loop and thiazide diuretics)

Question 38

what is the treatment for Hypomagnesaemia?

Answer 38

Mg salts if needed (oral/iv)

Question 39

The most serious consequence of potassium imbalances is:
A) seizure 
B) nerve damage 
C) renal failure 
D) cardiac abnormalities

Answer 39

D) cardiac abnormalities

Question 40

Which of the following can be caused by loop and thiazide diuretics:
A) hyponatraemia 
B) hypernatraemia 
C) hypokalaemia 
D) hyperkalaemia

Answer 40

A and C- hyponatraemia , hypokalaemia

Question 41

True or False: Corticosteroids can cause hypernatraemia

Answer 41

True

Question 42

What electrolyte imbalance can be treated using steroids, biophosphates and phosphate salts?

Answer 42

Hypercalcaemia

Question 43

Hypocalcaemia causes ……………… in serum parathyroid hormone as a consequence

Answer 43

Increase

Question 44

When supplementing phosphate it is also important to check ……….levels

Answer 44

calcium

Question 45

following the algorithm for the diagnosis of hyperkaelemia, how would you treat a person with a genuine increase in potassium levels over >6.5mmol/l

Answer 45

1) if potassium levels >6.5 mmol/l give emergency treatment
2) give IV calcium gluconate
3) give IV insulin with glucose and or nebulised salbutamol
4) give furosemide and/or calcium resonium consider dialysis
5) long term measures to prevent reassurance
- if the K+ level is below 6.5 mmol/l no Emerg treatment: diet restriction, stop sparing diuretics, potassium binding resin .