Increased loss from the digestive tract (most common)

Diarrhea

Vomiting

Laxatives if used a long time

Increased excretion in urine

Bartter syndrome

Cushing syndrome

Fanconi syndrome

Gitelman syndrome

Increased production of aldosterone due to a tumor in the adrenal glands

Liddle syndrome

A low level of magnesium (hypomagnesemia)

Diuretics (commonly)

Licorice (natural) if consumed in large amounts

Tobacco chewing (certain types)

Increased movement from blood into cells

An overactive thyroid gland (hyperthyroidism)

Insulin

Some medications used to treat asthma