Division of Endocrinology, Hospital das Clinicas, Federal University of Pernambuco, Recife, Brazil,
Pernambuco Endocrine Research Center, Recife, Brazil,
Neuroendocrinology. 2019;109(1):7-19. doi: 10.1159/000499694. Epub 2019 Mar 20.
An appropriate diagnostic evaluation is essential for the most appropriate treatment to be performed. Currently, macroprolactinemia is the third most frequent cause of nonphysiological hyperprolactinemia after drugs and prolactinomas. Up to 40% of macroprolactinemic patients may present with hypogonadism symptoms, infertility, and/or galactorrhea. Thus, the screening for macroprolactin is indicated not only for asymptomatic subjects but also for those without an obvious cause for their prolactin (PRL) elevation. Before submitting patients to macroprolactin screening and pituitary magnetic resonance imaging, one should rule out pregnancy, drug-induced hyperprolactinemia, primary hypothyroidism, and renal failure. The magnitude of PRL elevation can be useful in determining the etiology of hyperprolactinemia. PRL values >250 ng/mL are highly suggestive of prolactinomas and virtually exclude nonfunctioning pituitary adenomas (NFPAs) and other sellar masses as the etiology of hyperprolactinemia. However, they can also be found in subjects with macroprolactinemia, drug-induced hyper-prolactinemia or chronic renal failure. By contrast, most patients with NFPAs, drug-induced hyperprolactinemia, macroprolactinemia, or systemic diseases present with PRL levels <100 ng/mL. However, exceptions to these rules are not rare. Indeed, up to 25% of patients harboring a microprolactinoma or a cystic macroprolactinoma may also have PRL <100 ng/mL. Falsely low PRL levels may result from the so-called "hook effect," which should be considered in all cases of large (≥3 cm) pituitary adenomas associated with normal or mildly elevated PRL levels (≤250 ng/mL). The hook effect may be unmasked by repeating PRL measurement after a 1:100 serum sample dilution.
适当的诊断评估对于进行最合适的治疗至关重要。目前，巨泌乳素血症是继药物和泌乳素瘤之后导致非生理性高泌乳素血症的第三大常见原因。高达 40%的巨泌乳素血症患者可能出现性腺功能减退症、不孕和/或溢乳的症状。因此，不仅要对无症状患者，也要对那些催乳素（PRL）升高无明显原因的患者进行巨泌乳素筛查。在对患者进行巨泌乳素筛查和垂体磁共振成像之前，应排除妊娠、药物引起的高泌乳素血症、原发性甲状腺功能减退症和肾衰竭。PRL 升高的幅度有助于确定高泌乳素血症的病因。PRL 值>250ng/mL 高度提示为泌乳素瘤，几乎排除了无功能垂体腺瘤（NFPAs）和其他鞍区肿块是高泌乳素血症的病因。然而，它们也可能存在于巨泌乳素血症、药物引起的高泌乳素血症或慢性肾衰竭患者中。相比之下，大多数 NFPAs、药物引起的高泌乳素血症、巨泌乳素血症或系统性疾病患者的 PRL 水平<100ng/mL。然而，这些规则也有例外。事实上，高达 25%的微泌乳素瘤或囊性巨泌乳素瘤患者的 PRL 也可能<100ng/mL。PRL 水平假性降低可能是由于所谓的“钩状效应”所致，对于所有伴有正常或轻度升高的 PRL 水平（≤250ng/mL）的大型（≥3cm）垂体腺瘤患者，都应考虑这种效应。通过对 1:100 的血清样本进行稀释后重复测量 PRL，可以揭示钩状效应。
