Fluid & Electrolyte Balance

Question 1

Hypercalcaemia | Aetiology

Mild, mod, severe

Answer 1

Bones, stones, groans, psychic moans
(Weakness, fatigue, malaise)
(Abdo pain, constipation)
(Depression, confusion, coma)

Primary; idiopathic hyperPTHism
Secondary; malignancy (MM, lung SCC)
Inv ?cause; CXR, U&Es (CKD), FBC, ESR/CRP, TFTs, urinary Bence-Jones protein (MM), cortisol (Addison’s), urinalysis (protein CKD)

[Investigations]
Calcium, PTH, albumin
U&Es; dehydration
ECG; shortened QT interval
DEXA scan

[Management]
Aim to lower serum calcium
1. IV 0.9% saline rehydration
2. IV bisphosphonates; pamidronate infuse slowly through large vein
3. Chemotherapy; in malignancy
(Calcitonin)
(Loop diuretics; furosemide, to inhibit Ca reabsorption)

Question 2

Hyperkalaemia | Clinical features, Investigations & Management

Aetiology
Peri-arrest

Answer 2

Chest pain, palpitations, lightheadedness
Fast, irregular pulse

[Aetiology]
AKI, rhabdomyolysis, metabolic acidosis, Addison’s/ACEi/spironolactone, burns, tissue necrosis/apoptosis,

VBG; quicker than lab U&Es
ECG; tall tented T waves, broad QRS (+/- sinusoidal waveform), prolonged PR interval, small/absent P wave

[Management]

1. IV calcium gluconate 10%
2. IV insulin; 50ml of 50%
3. Assess and replace K
4. Salbutamol nebs; high doses required
5. Cardiac monitoring
6. RRT; if refractory/recurrent

Question 3

Hypokalaemia | Clinical features, Investigations & Management

Answer 3

Muscle weakness, hypotonia, hyporeflexia, cramps, tetany, palpitations, arrhythmias, lightheadedness, constipation

[Investigations]
Mg goes hand in hand with K
Bicarb high; if long standing, alkalosis
ECG; TdP Tx; IV MgSO4

[Management]

1. Oral K supplements (Sando-K)
2. Stop thiazide diuretic

Question 4

Hypernatraemia |

Answer 4

Weakness, lethargy, thirst, irritability, confusion, coma, seizures, dehydration

[Aetiology]
Diabetes insipidus, D&V, burns
Primary hyperaldosteronism
Iatrogenic; saline overload

[Management]

1. Oral water intake
2. IV glucose 5% 1L slowly