Hypomagnesemia

Question 1

Causes of hypomagnesemia

Answer 1

decreased intake: malnutrition, alcoholism,
Thiazides diuretics (increased loss)
Malabsorption or diarrhea (GI loss)
Bartter Gitelman syndrome
chronic PPI use

Question 2

Features of low magnesium?

Answer 2

neuromuscular excitability (tetany and seizures)
generalized weakness
atrial and ventricular arrhythmias

qtc prolongation

Question 3

laboratory findings of low magnesium

Answer 3

hypokalemia
hypocalcemia (low PTH release or resistance)
low serum mag level
ECG abnormalities like widened QRS

Question 4

WHy is magnesium important?

Answer 4

cofactor for over 300 enzymes and directly regulates sodium potassium and calcium

Question 5

What happens to K in refeeding syndrome?

Answer 5

shifts K into cells from extra cellular sites and lowers serum potassium, promoted by insulin.

also lowers phosphorus levels down too

Question 6

what causes low magnesium levels?

Answer 6

chronic alcohol abuse - excessive urinary excretion of magnesium and appears to reflect a reversible alcohol induced tubular dysfunction

Question 7

if you have hypomagnesemia you also see

Answer 7

hypokalemia

Question 8

how does hypomagnesemia also cause hypocalcemia?

Answer 8

low levels of magnesium also activate G proteins that stimulate calcium sensing receptors and decrease parathyroid hormone (PTH) secretion

low magnesium levels are also associated with resistance to PTH activity at the bone level.