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Corticosteroid Binding Globulin (CBG)
Test Code92590
CPT Codes
84449
Preferred Specimen
1 mL serum
Minimum Volume
0.5 mL
Transport Temperature
Frozen
Specimen Stability
Room temperature: 4 hours
Refrigerated: 24 hours
Frozen: 30 days
Refrigerated: 24 hours
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Received room temperature
Methodology
Immunoassay (IA)
FDA Status
This test was developed and its analytical performance characteristics have been determined by Pan Laboratories, Irvine, CA. This assay has been validated pursuant to the CLIA regulations. It has not been cleared or approved by the U.S. Food and Drug Administration.
Setup Schedule
Sets up 1 day a week.
Clinical Significance
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.