Name of the Test:
Corticosteroid Binding Globulin (CBG)
Transcortin, cortisol binding globulin
CBG determination is useful in assessing unexpected values of serum cortisol.
Coticosteroid 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.
CBG is quantitated in diluted serum/plasma samples using an immunometric assay ( sandwich ELISA ) using two antibodies , one as capture and other as detection antibody.
Test code # 117
Specimen requirements: 1.0 ml (minimum 0.5 ml) of serum.
Shipping requirements: Ship the samples frozen.
Turnaround time: Set up every Thursday and reported the same day.
Adults: 1.9 – 4.5 mg/dl
A. Mihrshahi R , Lewis JG Ali SO (2006 ) Hormonal effect on the secretion and glycoform profile of corticosteroid- binding globulin . J steroid biochemistry and mol boil 101: 275-285.
- Lewis JG, Lewis MG Elder PA (2003) An enzyme-linked immunosorbent assay for corticosteroid binding globulin using monoclonal and polyclonal antibodies: decline in CBG following synthetic ACTH. Clin chim Acta 328: 121-128.