Hypomagnesaemia Flashcards
In what hospital setting is hypomagnesaemia most common in
Intensive care units
In what two places in the body is magnesium most commonly lost in
Gastrointestinal tract
Kidneys
How can small deficits in magnesium lead to hypomagnesaemia?
There is an inability rapidly exchange between serum magnesium and the bony reserve
Hypomagnesaemia is commonly associated with other electrolyte derangement.
Give two examples of other electrolyte derangement it is commonly associated with
Hypokalaemia
Hypocalcaemia
Where is magnesium most commonly absorbed
Absorbed from the intestines (mostly in the small intestine but small amount from the large intestine)
Where in the kidneys is magnesium reabsorbed?
In the Loop of Henle in the thick ascending limb
What is the main reservoir of magnesium in the body
Bone
What endocrine system regulates magnesium levels
No major hormones that regulate magnesium
Thus exchange with serum concentrations is not freely accessible
Name some potential causes of hypomagnesaemia
- Decreased gut absorption
- Insufficient dietary intake
- Alcoholism
- Vomiting and Diarrhoea
- Malabsorption e.g. Crohn’s, Coeliac’s disease
- Small bowel bypass surgery
- Redistribution from extracellular to intracellular space
- Refeeding syndrome
- Acute pancreatitis
- Alcohol withdrawal
- Increased renal excretion
- Loop + thiazide diuretics
- PPIs
- Digoxin
Decreased gut absorption can result in hypomagnesaemia.
Name some causes of hypomagnesaemia secondary to decreased gut absorption
Insufficient dietary intake
Alcoholism
Vomiting and Diarrhoea
Malabsorption e.g. Crohn’s, Coeliac’s disease
Small bowel bypass surgery
Redistribution from extracellular to intracellular space can result in hypomagnesaemia.
Name some causes of hypomagnesaemia secondary to redistribution from extracellular to intracellular space
Refeeding syndrome - hence common in ICU
Acute pancreatitis
Alcohol withdrawal
Increased renal excretion can result in hypomagnesaemia.
Name some causes of hypomagnesaemia secondary to increased renal excretion
Loop + thiazide diuretics
PPIs
Digoxin
Describe some of the clinical features of hypomagnesaemia
- Majority as asymptomatic
- Neuromuscular
- Paraesthesia (numbness and/or tingling)
- Tetany (involuntary muscle spasms)
- Seizures
- CV
- Ventricular arrhythmias
- Chest pain
- Features of Hypocalcaemia
- Features of Hypokalaemia
How does hypomagnesaemia cause ventricular arrhythmias
Magnesium is an essential cofactor in the cardiac Na/K-ATPase pump.
Why does hypocalcaemia commonly seen in association with hypomagnesaemia
Low magnesium interferes with PTH release
PTH is important in calcium regulation (PTH increases the level of serum calcium)
