Biochemical Tests 1: Sodium

Question 1

What is the normal reference range of Sodium? (1)

Answer 1

135-145mmol/L

Question 2

What is reference range for mild hypernatraemia? (1)

Answer 2

145-149mmol/L

Question 3

What is the reference range for moderate hypernatraemia? (1)

Answer 3

150-169mmol/L

Question 4

What is the reference range for severe hypernatraemia? (1)

Answer 4

> = 170mmol/L

Question 5

What are the causes of hypernatraemia? (5)

Answer 5

Reduced H2O
Increased Na+ intake
H2O retention
Mineralcorticoid deficiency
Renal Failure

Question 6

What are the s/s of hypernatraemia? (15)

Answer 6

FRIED SALT +
Dry skin
Postural Hypotension
Urine output (low) / fluid retention
Confusion
Drowsiness / Lethargy
Severe = coma (> 155mmol/L)

Question 7

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

Answer 7

Corticosteroids
NSAIDs
Lithium
Soluble prep (e.g. paracetamol)
Injectables (e.g. Rifampicin, Gentamycin)

Question 8

Explain the management of hypernatraemia.

Answer 8

1. Identify + tx underlying cause e.g. reduce water/Na intake, temporarily withold or consider alternative drug.
2. Restore body H20: Oral (Mild), IV dextrose 5% (Moderate/Severe)
3. Monitor urine output, weight and Na+ levels after changes. Once normal levels are reached, reintroduce withheld drugs in lowest dose, may consider up titration to tolerable dose.

Question 9

What is the reference range for mild hyponatraemia? (1)

Answer 9

131-134mmol/L

Question 10

What is the reference range for moderate hyponatraemia? (1)

Answer 10

121-129mmol/L

Question 11

What is the reference range for severe hyponatraemia? (1)

Answer 11

<=120mmol/L

Question 12

What are the s/s of hyponatraemia?

Answer 12

LOW SODIUM +
Mild/Moderate: Headaches, Nausea, Muscle cramps /weakness, Confusion, Fatigue
Severe: Seizures, Respiratory Distress, Confusion.

Question 13

What are the causes of hyponatraemia? (8)

Answer 13

Medication
Mineralcorticoid deficiency
High H2O / fluid
Low Na+ intake (Diarrhoea/DKA)
Excessive Alcohol intake
Severe burns
Malnutrition
Blood sample dilution via I.V. Fluids

Question 14

Give e.g. of drugs that causes hyponatraemia. (6)

Answer 14

1. Diuretics: (Thiazide-like = Bendroflumethiazide/Indapamide), (Loop = Furosemide.)
2. Antidepressants (TCA = Amitriptyline), (SSRI = Fluoxetine, Paroxetine + Citalopram).
3. Anticonvulsants (Carbamazepine)
4. ACEi (Ramipril, Lisinopril, Enalapril.)
5. Sulphonylureas (Gliclazide, Tolbutamide)
6. PPI (Omeprazole, Pantoprazole)

Question 15

Explain the management of hyponatraemia. (3)

Answer 15

1. Identify and treat underlying cause e.g. increase + intake, fluid restriction, temporarily withholding causative medicines.
2. Mild/Moderate: Slow sodium 4-8 tablets / Demeclocycline 900mg-1200mg in divided doses. Severe = IV NaCl.
3. Monitor urine output, weight and Na+ levels. Once normal levels have reached, consider alternative drug/ reintroduce drug at lowest dose, potentially up titration to tolerable dose.