Irregular Heartbeat, Muscle Weakness and Fatigue, Asthma, Osteoporosis and cramps and muscle twitches are all signs and symptoms of a person experiencing a magnesium deficiency.
Magnesium deficiencies are typically caused by a decreased absorption of magnesium in the gut or increased excretion of magnesium in the urine.
Magnesium deficiencies are not normal in healthy people so you should see a doctor if you're experiencing a magnesium deficiency.