PTHrP has been found in various tissues, including prolactinomas and growth
hormone producing adenomas, The function and clinical importance of PTHrP
are poorly understood.
We report the case of a 25-year-old female patient with hirsutism. Autonomo
us ACTH-dependent hypercortisolism was documented by endocrine testing. Mag
netic resonance imaging (MRI) revealed a 3-mm intrasellar hypointense lesio
n in the left side of the pituitary gland. The inferior petrosal sinus samp
ling disclosed a gradient of ACTH left central/peripheral of 30.5 and right
central/peripheral of 2.0 and suggested the diagnosis of a left-sided pitu
itary ACTH secreting microadenoma.
Interestingly, we found elevated PTHrP levels in the left inferior petrosal
sinus with a gradient of 4.7 compared to peripheral venous blood and of 3.
6 compared to the right sinus.
Our results fit very well to the concept of a para-/autocrine secretion of
PTHrP which has been proposed recently and suggest a role in the regulation
of cell growth of pituitary adenomas.