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HelpEpic Test Code LAB103 Magnesium: Serum
Performing Location(s)
BMC,CRH,LFH,HRK,OCH,FTT,FOX,FCC
Specimen Type
Serum or Plasma
Preferred Container
Gold or Red top tube
Alternate Container
Green top tube
Blood Tube Draw Volume
Min 50% draw volume
Minimum Volume to Submit for Testing
0.5 mL Serum or Plasma
- Multiple test can be performed from this volume. For question please contact the lab at 547-3975.
Storage Requirements
Sample tubes should be centrifuged within 2 hours of collection
Gold tops DO NOT ALIQUOT
Aliquot Red tops
See Causes of Rejection for temperature requirements.
Transportation Needs
Deliver specimen to laboratory within 1 hour of collection if unspun. If not possible see "storage Requirements".
Causes for Rejection
Mislabeled or unlabeled specimen
Less than 50% draw for Vacutainer tubes
> 7 days refrigerated
> 24 hours room temperature
Hemolysis > 150 mg/dL HgB
Lipemia > 500 mg/dL Trig
Bilirubin > 36 mg/dL Bili
EDTA, NaF
Reference Values
|
Population |
Units |
Reference Range |
Low Critical Value |
High Critical Value |
|
All populations except Inpt. OB |
mg/dL |
1.9-2.7 |
<1.0 |
>4.0 |
|
Inpt. OB only |
mg/dL |
5.0-8.0 |
<1.0 |
>8.0 |
Additional Information
Contraindications:
Studies have shown that gadodiamide containing contrast media used in Magnetic Resonance Imaging (MRI) can produce analytic interference, both positive and negative, with assays performed in the clinical Laboratory for Calcium, Iron Magnesium, TIBC and Zinc. The package insert for Gadodiamide recommends waiting 12 to 24 hours between contrast agent administration and blood specimen collection to ensure that the contrast agent has been cleared. A longer waiting period might be necessary for patients with renal insufficiency. The average half-life of gadodiamide in patients with severely reduced renal function is 34 hours.
Inpatient OB patients administered MgSO₄ to prevent development of preeclampsia have a different therapeutic range and critical value from other patients (see ranges below).
Limitations
Because magnesium is three times more concentrated in erythrocytes than in serum, hemolyzed samples will give spuriously elevated results
Lipemia with triglyceride of 600 mg/dL [6.86 mmol/L] and bilirubin of 20 mg/dL [342 µmol/L] decreases the MG result by 0.6 mg/dL [0.25 mmol/L] and 1.0 mg/dL [17 mmol/L] respectively at a magnesium concentration of 1.8 mg/dL [0.74 mmol/L].
Lipemia with triglyceride of 600 mg/dL [6.86 mmol/L] does not affect the MG result (<0.1 mg/dL) [<0.05 mmol/L] at a magnesium concentration of approximately 2.0 mg/dL [0.82 mmol/L].
Capillary collected blood may differ from venous due to contamination from hemolysis or interstitial fluid.
Days of Analysis
All
Available STAT
Yes
Methodology
Beckman AU/Dx Series
CPT Code
83735
Last Updated
27-NOV-24 MS