Insulin, Total

Label Mnemonic:	INSLT
Epic code:	LAB7389
Downtime form:	Doctor/Provider Orders - Pathology Core and Specialty Care Nursery

Chemistry
6240 RCP
356-3527

Specimen(s):

Plasma

Collection Medium:

Plasma Separator Tube 4.5 mL

Alternate Collection Media:

Call laboratory for additional acceptable specimen collection containers.

Minimum:

3 mL whole blood from light green top tubes or TWO Microtainer^® devices from a fasting patient.

Delivery Instructions:

Deliver to laboratory immediately after collection.

Turn Around Time:

1 hour (upon receipt in laboratory)

Reference Range:

2.6 - 24.9 μU/mL (fasting)

Comments:

This assay may be significantly impacted by high-dose biotin (>5 mg dose) taken within previous 12 hours. High concentrations of biotin may lead to falsely decreased results. These concentrations may be found in patients taking over-the-counter supplements with biotin content much higher than nutritional requirements for biotin. Specimens should not be collected until at least 12 hours after the last dose.

Fasting for at least 8 hours prior to collection is recommended.

This assay has 100% cross-reactivity with endogenous insulin and recombinant human insulin (e.g., Novolin R and Novolin N). It does not recognize the insulin analogs lispro (Humalog), aspart (NovoLog), and glargine (Lantus). The mail-out test "Insulin, Random, Serum or Plasma" does cross-react with the insulin analogs and may be useful in determining whether a patient is taking one of these analogs (e.g., evaluating whether surreptitious insulin use may be causing otherwise unexplained hypoglycemia).

Test Limitations:

The assay is unaffected by icterus (bilirubin is less than 90 
mg/dL), lipemia (Intralipid is less than 1800 mg/dL) and biotin is 
less than 60 ng/mL (criterion: recovery within plus or minus 10% of 
initial value). Hemolysis is less than 60 mg/dL.

Samples from patients treated with bovine or porcine insulin sometimes 
contain anti-insulin antibodies which can affect the test results.(1-2)

As with all tests containing monoclonal mouse antibodies, erroneous 
findings may be obtained from samples taken from patients who have 
been treated with monoclonal mouse antibodies or have received them 
for diagnostic purposes. Elecsys Insulin contains additives which 
minimize these effects. In rare cases, interference due to extremely 
high titers of antibodies to streptavidin can occur.

For diagnostic purposes, Insulin findings should always be assessed in 
conjunction with the patient's medical history, clinical examination 
and other findings.

(1) Fiedler, H. Basiswissen Labordiagnostik: Diabetes mellitus und
    metabolisches Syndrom. Roche Diagnostics Brochure 1999;14,67 Cat
    No. 1951769.

(2) Tietz NW. Clinical Guide To Laboratory Tests. 3rd ed. Philadelphia,
    Pa: WB Saunders Co, 1995:366-367.

Methodology:

Electrochemiluminescence Immunoassay

CPT Code:

83525

See also:
Insulin, Random (Mailout), Serum or Plasma

See Additional Information:
Specimens Requiring Immediate Delivery
Fasting Specimen Requirements
Biotin Interference with Immunoassays