[Macroprolactinemia, a variety of hyperprolactinemia. Apropos of 5 cases]

Area of Science:

• Endocrinology
• Clinical Biochemistry

Background:

• Macroprolactinemia involves elevated circulating levels of large molecular weight prolactin variants.
• These big prolactin forms exhibit significantly reduced biological activity compared to monomeric prolactin.
• This condition can lead to misdiagnosis of clinically significant hyperprolactinemia.

Observation:

• Five patients presented with elevated immuno-reactive prolactin levels.
• These elevated levels were attributed to macroprolactin, a large molecular weight variant of prolactin.
• Macroprolactin demonstrated significantly weaker biological activity compared to monomeric prolactin.

Findings:

• Macroprolactinemia results in elevated immuno-reactive prolactin levels due to the 'big' prolactin variants.
• Despite high prolactin measurements, macroprolactinemia often lacks clinical significance due to the low bioactivity of these variants.
• Chromatography is essential for diagnosing macroprolactinemia by separating prolactin variants.

Implications:

• Macroprolactinemia represents a diagnostic pitfall in the evaluation of hyperprolactinemia.
• Accurate diagnosis through chromatographic methods prevents unnecessary investigations and treatments for patients with macroprolactinemia.
• Understanding prolactin variants is crucial for correct endocrine disorder assessment.