Drug/laboratory test interactions
Certain endocrine and liver function tests may be affected by estrogen-containing oral contraceptives. The following similar changes may be expected with larger doses of estrogens:
a. Increased prothrombin and factors VII, VIII, IX, and X, decreased antithrombin III; increased norepinephrine induced platelet aggregability.
b. Increased thyroid binding globulin (TBG) leading to increased circulating total thyroid hormone, as measured by PBI, T4 by column, or T4 by radioimmunoassay. Free T4 resin uptake is decreased, reflecting the elevated TBG, free T4 concentration is unaltered.
c. Impaired glucose tolerance.
d. Reduced response to metyrapone test.
e. Reduced serum folate concentration.
f. Increased serum triglyceride and phospholipid concentration.