Importance of macroprolactinemia in hyperprolactinemia

Area of Science:

• Endocrinology
• Clinical Biochemistry

Background:

• Macroprolactin is a complex of prolactin and immunoglobulin G, larger than monomeric prolactin.
• Macroprolactinemia is diagnosed when macroprolactin constitutes over 60% of total serum prolactin.
• Prevalence in hyperprolactinemic populations ranges from 15% to 35%.

Purpose of the Study:

• To define macroprolactin and macroprolactinemia.
• To elucidate the clinical significance and diagnostic challenges of macroprolactinemia.
• To differentiate benign macroprolactinemia from pathological hyperprolactinemia.

Main Methods:

• Polyethylene glycol precipitation for total prolactin measurement.
• Gel filtration chromatography as the gold standard diagnostic technique.
• Clinical assessment of hyperprolactinemic symptoms and pituitary imaging.

Main Results:

• Macroprolactin often presents with mild or no hyperprolactinemic symptoms due to reduced bioactivity and impaired clearance.
• Macroprolactinemia can be mistaken for true hyperprolactinemia, leading to diagnostic confusion.
• Elevated monomeric prolactin levels require investigation for underlying causes, irrespective of macroprolactin presence.

Conclusions:

• Macroprolactinemia is generally benign when bioactive monomeric prolactin levels are normal and symptoms are absent.
• Patients with macroprolactinemia and hyperprolactinemic symptoms require careful evaluation to rule out other causes.
• An individualized management approach is crucial, especially when macroprolactin is associated with pituitary adenomas or clinical manifestations.