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Test Name:
Insulin, Free and Total
- SBMF No:
30072 - Performance Lab Name:
Manual Lab - Test Mnemonic:
INSUL T/F - ABN:
Not required - CPT Code:
83525; 83527 - LOINC Code:
6901-3; 20448-7 - Test Includes:
Insulin, Free
Insulin, Total - Also Known As:
Free and Total Insulin - Also See:
30030 Insulin, Total - Spec Type:
Serum - Spec Container:
Gold top (SST) or red top (serum) tube - Alt Spec Type:
Plasma - Alt Spec Container:
Lavender top (EDTA) tube or green top (lithium heparin) tube - Pref Vol:
2.0 mL - Min Vol:
1.0 mL - Fasting:
No - Spec Collect:
Routine venipuncture - Spec Process:
Serum sample tubes, clot 30 minutes
Promptly centrifuge 15 minutes
Immediately transfer serum or plasma to separate plastic tube and freeze - Spec Store Transport:
Frozen - Spec Stability:
After separation from cells:
4 hours room temperature (20-30°C)
24 hours refrigerated (2-8°C)
6 months frozen (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles. - Spec Reject:
Serum or plasma in contact with RBC more than 1 hour
Sample not frozen within 24 hours of collection
Hemolyzed sample - Methodology:
Electrochemiluminescent Immunoassay (ECLIA) - Use:
Used to estimate active insulin concentrations in patients who have developed insulin antibodies - Clinical Significance:
Patients on insulin therapy can develop antibodies to insulin thus binding the free insulin and inactivating it. Therefore, the measurement of free insulin is necessary to estimate active insulin concentrations in these patients.
Many diabetic patients develop insulin resistance after insulin treatment, due to the formation of insulin antibodies. When present in sufficient quantities, these antibodies can cause resistance to insulin or stimulate the release of insulin at inappropriate times. Knowledge of insulin antibodies is important when a change in source of insulin is contemplated, or when the patient is not responding predictably to insulin therapy.
- Reference Range:
Insulin, Total: 2.6-24.9 µU/mL
Insulin, Free: Less than 25 µU/mL - Additional Test Info:
Limitations and Interferences:
• In patients receiving therapy with high biotin doses (i.e., greater than 5 mg/day), no sample should be taken until at least 8 hours after the last biotin administration.
• Samples from patients treated with bovine or porcine insulin sometimes contain anti-insulin antibodies that can affect the test results.
• 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.
• For diagnostic purposes, the results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings. - Day Run:
Sun-Sat (daily) - Time Run:
2:00 pm - Time Reported:
8 hours - Test Type:
HORMONE
