W6 - electrolyte cases Prof Sam

Question 1

A 67-year-old man was started on bendroflumethiazide for hypertension 2 weeks ago. He has had D& V for 2 days. He has dry mucous membranes and decreased skin turgor.
Urea & electrolytes:
• Na+: 129 mmol/L
• K+: 3.5 mmol/L
• Ur: 8.0 mmol/L
• Cr: 100 μmol/L
Clinical assessment? Likely cause? Management?

Answer 1

Clinical assessment => hypovolaemic hyponatraemia
Likely cause => D&V, diuretics
Management => volume replacement with 0.9% saline

Question 2

A 57-year-old woman has breathlessness worse on lying flat. Her past medical history includes a NSTEMI. She is on ramipril, bisoprolol, aspirin and simvastatin. She has elevated JVP, bibasal crackles and bilateral leg oedema. Urea & electrolytes:
Na+: 128 mmol/L
K+: 4.5 mmol/L
Ur: 8.0 mmol/L
Cr: 100 μmol/L
Clinical assessment? Likely cause? Management?

Answer 2

Clinical assessment => hypervolaemic hypoatraemia
Likely cause => HF
Management => Fluid restriction (0.5-1L/day), treat the underlying cause

Question 3

A 55-year-old man has jaundice. He has a past history of excessive alcohol intake. He has multiple spider naevi, shifting dullness and splenomegaly.
Urea & electrolytes:
Na+: 122 mmol/L
K+: 3.5 mmol/L
Ur: 2.0 mmol/L
Cr: 80 μmol/L
Clinical assessment? Likely cause? Management?

Answer 3

Clinical assessment => hypervolaemic hypoatraemia
Likely cause => cirrhosis
Management => Fluid restriction (0.5-1L/day), treat the underlying cause

Question 4

What is the link between cirrhosis and hyponatraemia?

Answer 4

in cirrhosis – you have excess nitric oxide release, you get dilatation, and you get low BP, this is picked up by baroreceptors, ADH release, water retention and you get low sodium

Question 5

A 40-year-old woman presents with fatigue, weight gain, dry skin and cold intolerance. On examination she looks pale.

Urea & electrolytes:
Na+: 130 mmol/L
K+: 4.2 mmol/L
Ur: 5.0 mmol/L
Cr: 65 μmol/L
Clinical assessment? Likely cause? Investigations? Management?

Answer 5

Clinical assessment => euvolaemic hyponatraemia
Likely cause => hypothyroidism
Investigations => TFTs
Management => thyroxine replacement

Question 6

A 45-year-old woman presents with dizziness and nausea. On examination she looks tanned and has postural hypotension.

Urea & electrolytes:
Na+: 128 mmol/L
K+: 5.5 mmol/L
Ur: 9.0 mmol/L
Cr: 110 μmol/L
Clinical assessment? Likely cause? Investigations? Management?

Answer 6

Clinical assessment => euvolaemic hyponatraemia
Likely cause =>Adrenal insufficiency
Investigations => Short synACTHen test => cortisol should go up in 30 mins, in Addison’s it wont!
Management => Treat the underlying cause: hydrocortisone and fludrocortisone

Question 7

A 62-year-old man has chest pain, cough and weight loss. He looks cachectic. He has a 30 pack year smoking history.
Urea & electrolytes:
Na+: 125 mmol/L
K+: 3.5 mmol/L
Ur: 7.0 mmol/L
Cr: 85 μmol/L
Clinical assessment? Likely cause? Investigations? Management?

Answer 7

Clinical assessment => euvolaemic hyponatraemia
Likely cause => SIADH (lung cancer + SIADH)
Investigations => Diagnosis of SIADH:
1. NO hypovolaemia
2. NO hypothyroidism
3. NO adrenal insufficiency
4. REDUCED plasma osmolality
AND
5. INCREASED urine osmolality (>100)
Management => specialist referral

Question 8

A 20-year-old man presents with polyuria and polydipsia. On examination he has bitemporal hemianopia.

Urea & electrolytes:
Na+: 150 mmol/L
K+: 4.0 mmol/L
Ur: 5.0 mmol/L
Cr: 70 μmol/L

Clinical assessment? Likely cause? Investigations?

Answer 8

Clinical assessment => hypernatraemia
Likely cause => DI
Investigations => for suspected DI:
- Serum glucose (exclude diabetes mellitus)
- Serum potassium (exclude hypokalaemia)
- Serum calcium (exclude hypercalcaemia)
- Plasma + urine osmolality
- Water deprivation test

Question 9

A 65-year-old man with type 2 diabetes mellitus and hypertension presents with malaise and drowsiness. He is on a basal bolus insulin regimen, ramipril, amlodipine, simvastatin and aspirin.
Urea & electrolytes:
Na+: 125 mmol/L
K+: 6.5 mmol/L
Ur: 18.0 mmol/L
Cr: 250 μmol/L

What is the abnormality? What is the underlying cause of it?

Answer 9

hyperkalaemia and raised creatinine

ramipril (ACEi) use is a cause. potentially also reduced GFR

Question 10

A 50-year-old man is referred with hypertension that has been difficult to control despite maximum doses of amlodipine, ramipril and bisoprolol.

Urea & electrolytes:
Na+: 140.0 mmol/L
K+: 3.0 mmol/L
Ur: 4.0 mmol/L
Cr: 70 μmol/L

What is the abnormality? What is the underlying cause of it? What initial investigation would you order?

Answer 10

hypokalaemia

+ hypertension

=> possibly conn’s disease!
=> aldosterone:renin ratio