Macroprolactin is the term used to describe a complex of serum
prolactin with an IgG antibody. This larger form of prolactin has
been recognised for a number of years and is found in some patients
with increased serum prolactin levels. Such patients, on
follow-up, have usually been found to show no characteristics of
the hyperprolactinaemic syndrome (infertility, menstrual
irregularity, galactorrhoea). Whereas monomeric prolactin is
bioactive, macroprolactin is considered biologically
The combination of apparent hyperprolactinaemia (due to
macroprolactin) and reduced bioactivity in vivo may cause
diagnostic confusion and lead to inappropriate treatment. Studies
have shown that in approximately 15% of patients with raised serum
prolactin the major reactive species was
Most laboratory assays for prolactin measure the prolactin
component of macroprolactin. Since macroprolactin remains in
the serum for longer than monomeric prolactin this leads to
apparently high circulating levels of prolactin.
Request on ICE
Analysed if specific criteria met.
All samples with increased serum prolactin will be examined for
the presence of macroprolactin.
3 to 5 days
If macroprolactin is detected a monomeric (bioactive) prolactin
level will be calculated and reported as well as the total