Serum Magnesium

Serum magnesium testing is covered when medically necessary for listed conditions (e.g., persistent hypocalcemia, unexplained lethargy/confusion except when due to established chronic psychiatric/neurologic diagnoses, pre‑eclampsia, neuromuscular irritability, arrhythmias including long QT/torsades, chronic diarrhea/malabsorption, renal/diuretic losses, monitoring during cisplatin/amphotericin/EGFR mAb therapy, long‑term parenteral nutrition, prolonged NG suction, or when monitoring oral/IV magnesium therapy); routine surveillance for patients with chronic mental‑health diagnoses is excluded. Key requirements: documentation of the clinical indication, relevant therapies/medications, and justification for the monitoring frequency per the LCD (e.g., monthly, every 2–3 weeks, ~6 months or annually as specified) is required for Medicare reimbursement and claims must include sufficient information to be processed under SSA Sections 1833/1862.

"Chronic diarrhea, otherwise unexplained and persistent."