Overview
Introduction
An adult serum magnesium concentration below 0.7 mmol/L (about 1.4 mg/dL) is hypomagnesemia.
NCLEX-RN
NCLEX-RN
An adult serum magnesium concentration below 0.7 mmol/L (about 0.58 mmol/L) is hypomagnesemia. The value is a starting point, not a complete severity assessment: symptoms, ECG changes, associated potassium or calcium abnormalities, ability to absorb oral therapy, and kidney function determine urgency. [1] Magnesium helps steady excitable tissues and supports ATP-dependent reactions, potassium retention, and parathyroid hormone activity. When it falls, the patient may develop tremor, cramps, tetany, seizures, hypokalemia that does not respond to potassium alone, hypocalcemia, QT prolongation, or ventricular dysrhythmias. A patient with ongoing diarrhea, alcohol use disorder, diuretic exposure, or malabsorption plus a persistently low potassium level should prompt a magnesium check. Replacement requires a second safety question: can the kidneys clear the dose? Reduced renal function increases the risk that magnesium will accumulate during treatment, so the prescribed dose, infusion rate, renal function, and post-dose magnesium level must be checked together.
Unlock full lesson + practice questions
9 more sections with scenarios, priorities, and review drills.
Final rapid review before practice
Next study step
Finish the lesson first, then choose a focused activity to apply what you just reviewed.
Continue studying
Sign in to save progress on this lesson.
Unlock the interactive lesson quiz with a plan that includes this NCLEX-RN pathway. You can still explore topic-filtered questions from the bank hubs below.