Hypomagnesemia means low levels of magnesium in the blood.
Low blood magnesium; Magnesium - low
Several conditions can cause hypomagnesemia, including:
Yu ASL. Disorders of magnesium and phosphorous. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 120.