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Test Code LAB103 Magnesium Serum

Clinical System Name

Magnesium Serum



Sample Requirements

Specimen: Whole Blood

Container(s): Lt. Green/Mint Top Lithium Heparin, Lt. Green/Lithium Heparin Microtainer, Gold SST, Gold Microtainer, Dark Green/Sodium Heparin, Red

Preferred Vol:  1.0 mL

Minimum Vol:  0.5 mL


Notes: Method is affected by hemolysis, EDTA, Na F-oxalate. Not affected by lipemia.

Processing Instructions

Reject due to:  Insufficient quantity, incorrect specimen container, hemolysis

Spin: Y

Aliquot: Y

Storage location:  Core Chemistry Refrigerator


Off-site collection: Avoid hemolysis. Specimen should be centrifuged within 2 hours of collection. Spin blood and transfer serum or plasma to plastic tube and refrigerate or freeze.


Specimen Type Temperature Time
Serum or Plasma RT

≤ 7 d

Serum or Plasma 2-8 C

≤  7 d

Serum or Plasma -20 C or -70 C

≤ 30 d


STAT Performed TAT
Y 24/7 1 h

Performing Laboratory

Seattle Children's Laboratory    


Department:  Core Chemistry

Phone Number: 206-987-2617 (Client Services)

CPT Codes



Method: Colorimetric method by Vitros 4600

Analytical Volume:  0.02 mL + 0.03 mL dead space

Reference Range

1.8 - 2.4 mg/dL


Magnesium deficiency may cause weakness, tremors, tetany, and convulsions.  Hypomagnesemia is associated with hypocalcemia, alcoholism, some types of malnutrition, malabsorption, chronic hemodialysis, and pregnancy.  Increased serum magnesium concentrations occur in patients with renal failure, dehydration, and Addison’s disease.  

Critical Values

≤ 1.0 mg/dL

≥ 5.0 mg/dL