Causes of high prolactin levels

Causes of high prolactin levels

What are the physiologic causes of an elevated prolactin level that must be considered in the differential diagnosis of prolactin-secreting tumors? What levels can be reached under these circumstances?

The most important physiologic states in which prolactin is found to be elevated are pregnancy and lactation. During the third trimester of pregnancy, the prolactin level may reach 200 to 300 ng/mL. It then gradually decreases during postpartum week 1 despite continued lactation but may continue to rise acutely at the time of breastfeeding. Prolactin values are also elevated during sleep, strenuous exercise, stress, and nipple stimulation. In these cases, the elevation is mild, < 50 ng/mL.

Abnormal Causes of high prolactin levels Other than Prolactin Secreting Tumors and Underlying Mechanism of Abnormal Prolactin Production

Pituitary stalk interruption
Pituitary, hypothalamic, or parasellar tumor
Infiltrative disorders of the hypothalamus
Interference with the hypothalamic–pituitary pathways: Prolactin production increases because the tonic inhibition of prolactin secretion is interrupted; often accompanied by hypopituitarism
Pharmacologic agents:
Tricyclic antidepressants
Specific interference with dopaminergic input to the pituitary gland
HypothyroidismIncreased thyrotropin-releasing hormone that stimulates prolactin release
Renal failure and liver cirrhosisDecreased metabolic clearance of prolactin; also, increased production in chronic renal failure
Intercostal nerve stimulation
Chest wall lesions
Herpes zoster
Mimicking of the stimulation caused by suckling

What are the typical levels of serum prolactin associated with these causes?

The prolactin level is usually mildly elevated, 30 to 50 ng/mL, and rarely above 100 ng/mL, when the cause of the elevated prolactin is not a prolactin-secreting tumor.


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