Test Mnemonic
CBG
CPT Codes
Aliases
- Corticosteroid Binding Globulin
- Transcortin
Performing Laboratory
Quest SJC
Specimen Requirements
| Volume |
Type |
Container |
Collect Temperature |
Transport Temperature |
Special Instructions |
| 1 mL | Serum | SST (Gold) | | Frozen | |
Alternate Specimen Requirements
| Volume |
Type |
Container |
Collect Temperature |
Transport Temperature |
Special Instructions |
| 1 mL | Serum | No additive (Red) | | Frozen | |
Minimum Specimen Requirements
| Volume |
Type |
Container |
Collect Temperature |
Transport Temperature |
Special Instructions |
| 0.5 mL | | | | | |
Stability
| Environmental Condition |
Description |
| Ambient | 4 hours |
| Refrigerated | 24 hours |
| Frozen | 30 days |
Days Performed
Wed
Turnaround Time
3 - 8 days
Methodology
| Name |
Description |
| Immunoassay (IA) | |
Reference Range
| Cortisol Binding Globulin |
| Sex |
Age From |
Age To |
Type |
Range |
Range Unit |
| | | | Normal | 1.9 - 4.5 | mg/dL |
Clinical Info
Corticosteroid binding globulin (CBG) is a serum alpha 2 globulin-binding protein with high affinity binding for cortisol. Cortisol binds to CBG approximately 92 % of blood levels and rest of the cortisol is as free or bound to serum albumin. CBG is synthesized in liver. The level of CBG is increased during pregnancy and individuals taking contraceptive pills. Elevated levels are also observed in acute hepatitis and in inherited abnormality. Insulin inhibits the synthesis of CBG. The serum level of CBG is lower in hyper-insulinemic status, as in diabetes, PCO and obesity. Severe liver disease and malnutrition may result in low level of CBG. Quantitation of CBG in serum may be useful in assessing unexpected levels of cortisol in serum.
