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### > Week 9: Biochemical Tests 1 > Flashcards

Week 9: Biochemical Tests 1 Flashcards

Includes: Sodium (Hyper/hyponatraemia) Potassium (Hyper/hypokalaemia) Chloride Bicarbonate Urea Creatinine

1
Q

What is the reference range for sodium?

A

135-145mmol/L

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2
Q

What is the definition of hypernatraemia?

A

Plasma sodium concentration of > 145mmol/L.

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3
Q

What are the general causes of hypernatraemia? (2)

A
  1. Water Depletion:
    • Loss of water to sodium
      excess.
    • Decreased fluid intake.
  2. Increased sodium intake / water excess retention:
    • Mineralcorticoid excess
    • Medication
    • Renal Failure
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4
Q

What are the signs and symptoms of hypernatraemia? (8)

A

Dry Skin
Postural Hypotension
Oliguria (little urine production)
Thirst
Confusion
Drowsiness
Lethargy
Extreme cases - coma (>155mmol/L)

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5
Q

Give examples of drugs that can cause hypernatraemia. (7)

A

Corticosteroids
NSAIDs
Laxatives
Lithium
Injectables
Soluble prep. e.g. paracetamol, co-codamol
Antibiotics e.g. gentamycin, rifampicin

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6
Q

Explain the management process for hypernatraemia. (2)

A
  1. Identify + treat underlying cause (e.g. medicines should be changed to an alternative if it has recently been introduced)
  2. Replace body water:
    Orally (Mild)
    I.V. Dextrose 5% (Moderate/Severe)
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7
Q

What are the severity ranges for hypernatraemia? (3)

A

Mild: 146-149mmol/L
Moderate: 150-169mmol/L
Severe: >170mmol/L

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8
Q

How should IV dextrose 5% be administered? (1)

A

It should be given slowly at a rate of 12mmol over 24 hours to reduce the risk of cerebral oedema.

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9
Q

What monitoring is considered for altered sodium levels? (3)

A

Urine output
Weight
Fluid status

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10
Q

What is the definition of hyponatraemia?

A

Plasma sodium conc. <135mol/L.

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11
Q

What are the severity ranges for hyponatraemia? (3)

A

Mild: 130-135mmol/L
Moderate: 121-129mmol/L
Severe: <120mmol/L

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12
Q

What are the signs and symptoms for mild/moderate hyponatraemia? (6)

A

Headaches
Nausea
Fatigue
Cramps
Muscle Weakness
Confusion

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13
Q

What are the signs and symptoms of severe hyponatraemia? (3)

A

Seizures
Coma
Respiratory Arrest

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14
Q

What factors cause hyponatraemia? (2)

A

Over hydration +/or Low sodium intake

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15
Q

What are the causes of hyponatraemia? (8)

A

Medications
Mineralcorticoid deficiency
Water/fluid excess
Abnormal losses of sodium
Alcohol excess
Severe burns
Malnutrition
Blood sample dilution by IV fluids.

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16
Q

Give e.g. of drugs that can can cause hyponatraemia. (6)

A
  1. Diuretics:
    • Thiazide: Bendroflumethiazide, Indapamide
    • Loop: Furosemide
  2. Antidepressants:
    • SSRI: Fluoxetine, Paroxetine, Citalopram
    • TCA: Amitriptyline
  3. Anticonvulsants: Carbamazepine
  4. ACEi’s: Ramipril, Lisinopril, Enalapril.
  5. Sulphonylureas: Gliclazide, Tolbutamide
  6. PPI’s: Omeprazole, Pantoprazole.
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17
Q

Explain the management process for hyponatraemia.

A
  1. Identify and correct underlying cause e.g. increase salt intake/fluid restriction.
  2. If needed:
    Mild-Moderate: Slow sodium, 4-8 tablets (2.4-4.8g) OR
    Demeclocycline 900-1200mg daily in divided doses.
    Severe: I/V NaCl
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18
Q

At what rate should IV NaCl be administered?

A

It should be administered slowly to reduce the risk of osmotic demyelination.

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19
Q

What are the severity ranges for hyperkalaemia?

A

Mild: 5.5-5.9mmol/L
Moderate: 6.0-6.4mmol/L
Severe: ≥ 6.5mmol/L

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20
Q

What are the causes for hyperkalaemia? (10)

A

Medication
Renal (AKI/CKD/Rhabdomyolysis/Hypoaldosteronism)
Advanced CCF
Acidosis
DKA
Severe Tissue Damage
Hormonal Effects
Fragile Blood Cells
Diet

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21
Q

What is pseudohyperkalaemia?

A

An artificial rise in K+ levels due to an underlying cause.

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22
Q

What can cause pseudohyperkalaemia?

A

Delay in sample reaching lab
Contamination
Haemolysis of sample
Drip arm

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23
Q

What are the signs and symptoms of hyperkalaemia? (6)

A

Fatigue
Muscle Weakness
Abnormal Cardiac Conduction:
- Chest pain + palpitations
- ECG changes
- Cardiac Arrest (severe)

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24
Q

What signs and symptoms of hyperkalaemia would be considered as a medical emergency? (3)

A

1 or more:
Severe hyperkalaemia (> 6.5mmol/L)
ECG changes
Chest pain + palpitations

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25
Q

Explain the management process for hyperkalaemia. (5)

A
  1. Assess patient: ABCDE
  2. Identify cause/stop potentially offending drugs immediately.
  3. Rule out pseudohyperkalaemia.
  4. Ensure adequate hydration.
  5. Consider severity: Severe/ECG changes (Medical emergency)
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26
Q

Explain how mild/moderate hyperkalaemia is managed in community. (2)

A
  1. Mild (5.5-5.9mmol/L):
    • Correct underlying cause, repeat blood test
    • Medication review and dietary changes.
  2. Moderate (6-6.4mmol/L):
    • Carry out an ECG
      • Assess course of action based on results
      • No high-risk factors, review patient.
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27
Q

Explain when hospital referral is considered for hyperkalaemia. (3)

A

> 6.5mmol/L
Acute ECG changes and > 5.5mmol/L
Rapid rise

28
Q

Outline the 5 step approach to managing hyperkalaemia in hospitals.

A

Protect heart
Shift K+ into cells
Remove K+ from body
Monitoring
Prevention

29
Q

Explain the process of protecting the heart in hyperkalaemic patients.

A

If ECG changes are present:
1. 30ml of 10% Ca Gluconate IV OR 10ml of 10% Ca chloride IV.

Antagonises cardiac excitability.

30
Q

What is the interaction between digoxin and calcium gluconate?

A

It can increase digoxin toxicity causing arrhythmias.

31
Q

How should calcium gluconate be administered? (2)

A

20-30 mins intervals at a slow rate via infusion.

Then it’s reconstituted to 100ml of glucose.

32
Q

If a patient has high calcium levels, what medications should not be given if they experience hyperkalaemia? (2)

A

Calcium gluconate/chloride

33
Q

Explain the process of shifting potassium into cells. (4)

A
  1. Insulin-glucose infusion:
    • 10 units soluble insulin in 250ml dextrose 10%
  2. 10-20mg salbutamol nebuliser (IHD)
  3. Doesn’t reduce total body K+ = will start to leak back into extracellular space (2-6 hrs)
  4. Shift into cells TEMPORARILY!
34
Q

Explain the process of removing potassium. (4)

A

Potassium exchange polymers:
- Anion exchange resin
- Potassium binders

Dialysis

35
Q

Give example of an anion exchange resin that treats hyperkalaemia.

A

Calcium resonium 15g TDS

36
Q

Give e.g. of potassium binders that treats hyperkalaemia. (2)

A

Patiromer calcium (8.4g OD)
Lokelma (sodium zirconium cyclosilicate)

37
Q

Counsel a patient on using Patiromer calcium (3)

A

It’s taken orally - 8.4g OD adjust dose acc.
Onset of action = 4-7 hrs
Can cause GI irritation and reduced Mg levels.

38
Q

Counsel a patient on Lokelma (sodium zirconium cyclosilicate) (4)

A

Orally administered (10g up to TDS for up to 72 hrs)
45ml H20
Onset of action = 1hr
Common s/e = fluid imbalance/retention, oedema.

39
Q

When would dialysis be used as a treatment option to remove K+ levels? (3)

A

Used as 3rd line treatment if Anion exchange resin and potassium binders are ineffective.
Need to contact with critical care team and renal consultant/registrar for additional advice.

40
Q

What monitoring is considered for hyperkalaemic patients? (4)

A
  1. Continuous cardiac monitoring where ECG features are present.
  2. K+ levels every 2-4 hrs.
  3. Blood glucose levels
  4. Baseline, 15,30,60,90,120 minutes and up to 6hrs post dose.
41
Q

What are the treatment aims for hyperkalaemia? (4)

A

Improved patient health
Optimal tx and return home
Optimise and ongoing monitoring
Advise sick day rules (withold meds temporarily) - prevents hyperkalaemia during acute illness (sepsis to AKI)

41
Q

Explain the process of preventing hyperkalaemia. (2)

A

Stop nephrotoxic medications and drugs that cause hyperkalaemia.

41
Q

What are the severity ranges for hypokalaemia?

A

Mild <3.5mmol/L
Moderate 2.5-3mmol/L
Severe <2.5mmol/L

42
Q

Give e.g. of drugs that cause hyperkalaemia. (7)

A

ACEi
K+ sparing diuretics
ARBs
K+ supplements
Trimethoprim (CKD)
NSAIDs
K+ containing laxatives

43
Q

What are the causes of hypokalaemia? (4)

A

Medication
Decreased K+ intake
Abnormal losses = D+V, Ileostomy
Acid-base disturbances

44
Q

What are the signs and symptoms of hypokalaemia? (6)

A

Hypotonia (reduce muscle tone)
Cardiac Arrhythmias
Muscle Weakness
Fatigue
Confusion
Paralytic Ileus

45
Q

Give e.g. of drugs that cause hypokalaemia (5)

A

Salbutamol (high doses)
Diuretics (Loop/Thiazide)
Insulin
Steroids
Chronic laxative abuse

45
Q

Explain the management process for mild/moderate hypokalamia. (3)

A
  1. Sando K: 1-2 tablets TDS
  2. Kay-Cee-L: 10-20ml TDS
  3. Slow K: Avoid
46
Q

Explain the management process for severe hypokalaemia. (1)

A

IV replacement (w/ continuous cardiac monitoring - depending on K+ conc.)

47
Q

What does the NPSA state about administering K+ permanganate?

A

It can increase the risk of of death or serious harm to the patient if taken orally.

48
Q

What is the interaction between digoxin and hypokalaemia? (2)

A

This increases the risk of digoxin toxicity.
Digoxin competes with K+ ions at binding sites hence, lowers K+ levels predisposing to toxicity.

49
Q

What is the reference range for Chloride?

A

95-105mmol/L

50
Q

What are the causes of increased Cl- levels? (2)

A
  1. Excess ingestion
  2. Dehydration
51
Q

What are the causes for reduced Cl- levels?

A
  1. Vomiting
  2. Diarrhoea
  3. Diuresis
  4. Dehydration
52
Q

What is the reference range for Bicarbonate?

A

24-30mmol/L

53
Q

What are the causes for increased bicarbonate levels? (5)

A
  1. Excess antacids
  2. Thiazide/loop diuretics
  3. Metabolic alkalosis
  4. Hypokalaemia
  5. Vomiting
53
Q

What are the causes for decreased bicarbonate levels? (5)

A
  1. Diarrhoea
  2. Renal Failure
  3. Diabetes Mellitus
  4. Metabolic Acidosis
  5. Respiratory Alkalosis
53
Q

What is the main symptom indicating high bicarbonate levels?

A

Vomiting

54
Q

What are the signs and symptoms for reduced bicarbonate? (3)

A

Headache
Drowsiness
Coma (severe acidosis)

55
Q

What is urea? (3)

A

End product of protein/muscle metabolism.

Excreted from kidneys in unchanged form.

If kidney filtration is impaired, serum creatinine levels will rise.

56
Q

What are the causes for high urea levels?

A
  1. Renal Failure
  2. Sepsis
  3. Urinary Tract Obstruction (UTO)
  4. CCF
  5. Dehydration
  6. GI bleed
57
Q

What are the causes for low urea levels? (5)

A
  1. Pregnancy
  2. Low protein intake
  3. Chronic Liver Disease
  4. Overhydration
  5. Starvation
58
Q

Explain what process of creatinine undergoes. (1)

A

Creatinine undergoes complete glomerular filtration and its clearance is a marker of GFR.

59
Q

What is GFR? (2)

A

Glomerular Filtration Rate:
- Rate at which kidney filters and it varies with age + gender.
- Levels of creatinine will correlate with lean body mass.

60
Q

What are the causes for increased creatinine levels? (3)

A
  1. Dehydration
  2. Renal Failure
  3. Urinary Tract Obstruction
61
Q

What are the causes for reduced creatinine levels? (2)

A
  1. Pregnancy
  2. Chronic Muscle Wasting

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