Screening for macroprolactinaemia and pituitary imaging studies.

Area of Science:

• Endocrinology
• Clinical Chemistry

Background:

• Hyperprolactinaemia results from elevated prolactin levels, with monomeric, dimeric, or macro forms circulating.
• Macroprolactinaemia is frequently observed and often linked to asymptomatic cases.
• Monomeric prolactin is predominant in patients with prolactinomas.

Purpose of the Study:

• To review clinical and imaging investigations in patients with hyperprolactinaemia predominantly due to macroprolactin.
• To compare findings in macroprolactinaemia patients with those having predominantly monomeric prolactin.

Main Methods:

• Retrospective study of 113 hyperprolactinaemia patients.
• Screening for macroprolactin using polyethylene glycol precipitation and/or chromatography.
• Pituitary magnetic resonance imaging (MRI) and/or computerized tomography (CT) were performed.

Main Results:

• 46% of patients had macroprolactinaemia; 54% had monomeric hyperprolactinaemia.
• Macroprolactinaemia patients were more likely to be asymptomatic (46%) compared to monomeric form patients (10%).
• 78.9% of macroprolactinaemia patients had normal pituitary imaging, versus 25% with monomeric hyperprolactinaemia.

Conclusions:

• Macroprolactinaemia does not rule out pituitary adenoma, but asymptomatic patients with macroprolactin typically have normal imaging.
• Testing for macroprolactin before pituitary imaging is recommended to avoid unnecessary procedures.
• Pituitary imaging in macroprolactinaemia patients should be reserved for cases with clinically relevant features.