ABN Requirement: No
CPT Code:
IROGTT, 2 Samples: 83525 (x2)
IROGTT, 3 Samples: 83525 (x3)
Each additional sample: 83525
Order Code:
IROGTT, 3 Samples (Fasting, 1 hour, 2 hour): C559
IROGTT, 2 Samples (Fasting, 1 hour): C558
IROGTT, 2 samples (Fasting, 2 hour): 1344
IROGTT, Additional Insulin 1: 1419
IROGTT, Additional Insulin 2: 1420
Specimen: Serum
Volume: 1.0 mL (per timed specimen)
Minimum Volume: 0.5 mL (per timed specimen)
Container: Gel-barrier tube (SST)
Fasting: Overnight fasting is required.
Patient Preparation:
Overnight fasting is required. High carbohydrate diet for 3 days before test. Patient NPO after midnight; glucose solution 1.75 g/kg body weight (maximum dose 75g) orally administered after collection of the fasting specimen
Collection:
- Draw fasting specimen. Collect 1 mL serum for each timed specimen post glucose dose. All tubes must be clearly labeled with the time of draw. Submit all tubes with one test requisition.
- Collect and label sample according to standard protocols.
- Gently invert tube 5 times immediately after draw. Do not shake.
- Allow blood to clot 30 minutes.
- Centrifuge for 10-15 minutes.
Transport: Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions included with the provided shipping box.
Stability:
Ambient (15-25°C): 24 hours
Refrigerated (2-8°C): 7 days
Frozen (-20°C): 28 days
Causes for Rejection: Specimens other than serum; improper labeling; samples not stored properly; samples older than stability limits; hemolysis; plasma; gross icterus
Methodology: Immunoassay (IA)
Turn Around Time: 1 to 3 days
Reference Range:
| Insulin Response to Glucose | Reference Range |
|---|---|
| Fasting | 2.0-18.4 uIU/mL |
| 30 minutes post glucose | 6.0-86.0 uIU/mL |
| 60 minutes post glucose | 8.0-112.0 uIU/mL |
| 90 minutes post glucose | 5.0-68.0 uIU/mL |
| 120 minutes post glucose | 5.0-55.0 uIU/mL |
| 150 minutes post glucose | 3.0-46.0 uIU/mL |
| 180 minutes post glucose | 3.0-20.0 uIU/mL |
| 240 minutes post glucose | <15.0 uIU/mL |
| 300 minutes post glucose | <8.0 uIU/mL |
Clinical Significance: The insulin response to glucose infusion is useful in evaluating patients with hypoglycemia and suspected insulin resistance.
The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.