Electrolyte Disorders

Question 1

Hypomagnasaemia

Answer 1

Mag < 0.8mmol/L
- Causes
- Severely ill patients. Malabsorption. Poor oral intake
- Associated contributors
- Diabetes, alcoholism, diuretic drugs
- Symptoms
- Minimal in mild deficiency
- Severe - Tetany, muscle weakness, cardiac arrhythmias, convulsion, neuropsychiatric changes
- Treatment
- Oral magnesium aspartate 1000-3000mg PO daily in divided doses
- Severe? IVIF

Question 2

Hypermaganasaemia

Answer 2

Mag > 1.0mmol/L
- Causes - Iatrogenic. Excessive intake. Kidney impairment. Rhabdomyolysis. Lithium
- Clinical features - loss of deep tendon reflexes. Muscle paralysis. Impaired consciousness. Respiratory depression. Anorexia. Nausea. Skin flushing. Hypotension. Bradycardia. Heart block

Rx - Withdraw magnesium intake. Can use IV Ca infusion to transiently antagonise effect of Mag.
- Diuresis - IV Normal saline aim for urine output of 60mL/hr minimum.

Question 3

Hypercalcaemia

Answer 3

Corrected Ca > 2.6mmol/L
Clinical features - Abdominal pain, failure to thrive in infant, constipation, polyuria, polydypsia, cardiac arrhythmia.
Causes
- Primary hyperparathyroidism, Hypercalacaemia from malignancy, Thiazide diuretics, sacroidosis, Vit D toxicity, Paget’s disease

Investigations
- PTH (Primary hyperparathyroidism)
- EUC
- ALP (Paget’s)
- CXR (Sarcoidosis)
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