Thyroxine-binding globulin (TBG) may be measured directly by radioimmunoassay. Estrogens elevate serum TBG levels; thus, women who are pregnant, who are receiving estrogen therapy or oral contraceptives, or who have estrogen-secreting tumors have higher TBG levels.
Nursing Care Before the Procedure
Client preparation is essentially the same as that for any study involving the collection of a peripheral blood sample (see Appendix I).
A venipuncture is performed and the sample collected in a red-topped tube. The sample should be handled gently to avoid hemolysis and transported promptly to the laboratory.