Key differential diagnoses of hyperprolactinemia

Many people are confused after suffering from hyperprolactinemia, which is caused by the lack of knowledge about this disease. In fact, hyperprolactinemia exists around us, and many people suffer from this disease. After suffering from this disease, examination is a very important task. What are the main differential diagnoses of hyperprolactinemia?

1. Inspection

1. FSH and LH decreased in the hypothalamus-pituitary-ovarian axis reproductive hormone test, and the LH/FSH ratio increased. For example, PRL 100ng/ml is mostly functionally elevated, and PRL 100ng/ml is mostly tumor-induced. The larger the tumor, the higher the PRL. For example, if the tumor diameter is 5mm, the PRL is (17138)ng/ml; if the tumor diameter is 5-10mm, the PRL is (20629)ng/ml; if the tumor diameter is 10mm, the PRL is mostly (485158)ng/ml. Plasma PRL may not increase when giant adenomas bleed and necrotize.

2. Thyroid, adrenal and pancreatic function tests: When hyperprolactinemia is combined with hypothyroidism, TSH is elevated, and T3, T4, and PBI are decreased. When hyperprolactinemia is combined with Cushing's disease and virilization symptoms, testosterone (T), androstenedione (△4dione), dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), 17-ketosteroids (17KS) and plasma cortisol are elevated. When hyperprolactinemia is combined with diabetes and acromegaly, plasma insulin, blood sugar, glucagon should be measured and a glucose tolerance test should be performed.

2. Identification

1. Normal prolactin galactorrhea Some women have galactorrhea but normal blood PRL levels, which is called normal prolactin galactorrhea (normoprolactinaemiclactorrhea). Normal prolactin galactorrhea is not uncommon. According to foreign data, 28% to 55% of women with galactorrhea have normal blood PRL levels. Normal prolactin galactorrhea is more common in women of childbearing age, and menstrual disorders are less common (about 1/3). Some patients' galactorrhea is related to normal pregnancy and breastfeeding. These women still have milk secretion after stopping normal breastfeeding, and it lasts for a long time. Others are related to oral contraceptives, and some are unknown. At present, the mechanism of normal prolactin galactorrhea is not very clear. Some people believe that there is a variant PRL in the patient's body, which has normal biological activity but cannot be measured by the usual radioimmunoassay, so the patient has galactorrhea but normal blood PRL level; some people believe that it may be caused by the increase in the level of other hormones with prolactin activity (such as hGH) in the body. However, the above view has not been confirmed so far. At present, most scholars believe that it is caused by the increased sensitivity of patients to PRL. As for the reason for the increased sensitivity of the body to PRL, it is still unclear, and it may be related to the increase in PRL receptor levels. Johnston et al. believe that the PRL receptor levels of normal women have a physiological increase during pregnancy and lactation. After stopping lactation, the blood PRL and breast PRL receptor levels return to normal, but a small number of patients have some defects that keep the PRL receptor at a high level after stopping lactation. Therefore, although the blood PRL level is normal, there is still galactorrhea (the formation mechanism of those caused by oral contraceptives is similar to this). Some people use a small dose of bromocriptine (although the blood PRL level is normal) to reduce the blood PRL level to the lower limit of normal, and the galactorrhea symptoms can be improved, which also supports this view.

The characteristic of normoprolactinemic galactorrhea is the normal secretion of PRL. Not only does the patient have a normal basal PRL level, but the response to hypoglycemia and TRH is also normal, which can be used to distinguish it from galactorrhea caused by hyperprolactinemia.

2. Identification of the cause of hyperPRLemia After confirming the presence of hyperPRLemia, further etiological diagnosis should be made. First, the medical history should be inquired in detail to determine whether hyperPRLemia is caused by drugs. Secondly, liver and kidney function should be measured to determine whether hyperPRLemia is caused by cirrhosis or renal failure. The determination of TSH, T3, and T4 is necessary. If TSH, T3, and T4 are all significantly increased, it may be hyperPRLemia caused by pituitary TSH tumor; if TSH is increased and T3 and T4 are decreased, it may be hyperPRLemia caused by primary hypothyroidism. At the same time, blood GH, ACTH, and cortisol levels should be measured to determine whether GH tumors and ACTH tumors exist, because they can both cause hyperPRLemia. The determination of FSH/LH and subunits is helpful for the diagnosis of gonadotropins and non-functional pituitary adenomas, which is also valuable for distinguishing the causes of hyperPRLemia.

Pituitary CT, MRI examination and blood PRL determination are of great significance for etiological diagnosis. Generally speaking, if CT and MRI have positive findings and the blood PRL level exceeds 9.1nmol/L (200ng/ml), the diagnosis of PRL tumor can be established. The blood PRL level is closely related to the size of the tumor. The blood PRL level of macroadenomas is mostly above 11.38nmol/L (250ng/ml), while that of microadenomas is mostly below 9.1nmol/L (200ng/ml). If the blood PRL level is only slightly to moderately elevated (below 9.1nmol/L) and CT and MRI show a macroadenoma, the tumor is often not a true PRL tumor, but a so-called pseudo-PRL tumor.

In recent years, 11C-labeled dopamine D2 receptor antagonists methylspiperone and raclopride have been used for PET imaging, which is not only of diagnostic significance, but also can predict the efficacy of dopamine receptor agonists. Generally speaking, those who can be imaged respond well to dopamine receptor agonists.

The examinations for hyperprolactinemia are those introduced above. Patients must undergo relevant examinations after becoming ill. Only after a confirmed diagnosis can we treat the disease. Therefore, this examination link is very important and everyone must pay attention to it.