Which of the following tests is most sensitive for the diagnosis of a pituitary adenoma?
A. Serum prolactin measurementB. Visual field examination
C. CT scan with contrast injection
D. MRI with gadolinium injection
Ans. D. MRI gadolinium injection
MRI with gadolinium is the most
sensitive test for the detection of microadenomas, revealing them in 1O%—20% of
normal women. Oversecretion of prolactin is present in only 30%—50% of patients
with pituitary adenomas. Impaired GH response to insulin- induced hypoglycemia
or visual field changes would occur only in those tumors that are large enough
to interfere with normal pituitary function or to compress the optic chiasm. CT
scans reveal very small adenomas, but MRI with gadolinium is even more
sensitive.