Test Code MG Magnesium, Plasma or Serum
Additional Codes
Compendium Code (Iatric): L300.1650
Performing Laboratory
St. Lukes Hospital Laboratory
Methodology
Colorimetric with Xylidyl Blue
Specimen Requirements
Separated specimens may be stored for up to 7 days at 2 - 8°C.
Submit only 1 of the following specimens:
Plasma Draw blood in a green-top (lithium heparin) plasma
gel tube(s). Spin down and send 1 mL of lithium heparin plasma
refrigerated.
Note: 1. Indicate plasma on request
form.
2. Label specimen appropriately (plasma).
Serum
Draw blood in a serum gel tube(s). Spin down and send 1 mL of serum
refrigerated.
Note: 1. Indicate serum on request form.
2. Label specimen appropriately (serum).
Unspun specimens must be transported at ambient temperature and arrive to the laboratory within one hour of draw.
Reference Values
1.5-2.4 mg/dL
Critical values (automatic call-back): <0.5 mg/dL or >5 mg/dL
Interfering Substances:
Hemolysis will cause an increase in magnesium. Lipemia can cause falsely-decreased magnesium.
Day(s) Test Set Up
Monday through Sunday
Test Classification and CPT Coding
CPT: 83735
LOINC: 19123-9