Abstract
Macroprolactinemia frequently causes misdiagnosis, unnecessary investigation and inappropriate treatment in hyperprolactinemic patients. Aim of this study is to investigate the prevalence and clinical characteristics of Thai patients with macroprolactinemia. We performed a cross-sectional study in 56 hyperprolactinemic patients (51 women and 5 men) whose sera were subsequently tested for the presence of macroprolactin. Recovery of less than 40% of serum prolactin after polyethylene glycol (PEG) precipitation was indicative of macroprolactinemia. Our study revealed 19.64% (11/56) of patients with hyperprolactinemia were found to have a preponderance of macroprolactin. All patients with macroprolactinemia were women, of which eight of them were initially diagnosed as idiopathic hyperprolactinemia and mistreated with dopamine agonist medications. Interestingly, neuroradiological abnormalities were reported in three patients with macroprolactinemia, 2 cases with prolactinoma and one case with stalk effect hyperprolactinemia. In conclusion, nearly one-fifth of our patients with hyperprolactinemia have macroprolactinemia. This finding suggests that the diagnostic algorithm of all patients with hyperprolactinemia should include the PEG precipitation test as the initial step.Domain: Endocrinology
Highlights
Hyperprolactinemia is a common endocrine problem in general practice
Macroprolactin accounts for less than 5% of circulating PRL and can interfere with all currently available commercial PRL immunoassays leading to falsely elevated PRL levels in terms of macroprolactinemia1
Errors in PRL measurement from falsely lowered levels or hook effect and falsely elevated levels or macroprolactinemia result in unnecessary investigation and inappropriate treatment in hyperprolactinemic patients [1,9]
Summary
Hyperprolactinemia is a common endocrine problem in general practice. It manifests mainly as reproductive and sexual dysfunction including amenorrhea or oligomenorrhea, galactorrhea and infertility in women or loss of libido in men [1, 2]. Prolactin (PRL) circulates in human sera in three major forms according to their molecular size; monomeric (23 kDa), big or dimeric (45-60 kDa) and big-big (150-170 kDa) or macroprolactin. Monomeric form is the most prominent form (85-95%) of the circulating PRL and is known to be biologically and immunologically active. The aim of this study is to investigate the prevalence of macroprolactinemia in hyperprolactinemic Thai patients by using PEG precipitation, and to determine the clinical and neuroradiological features of affected individuals
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