Macroprolactin

PRL is a glycoprotein synthesized in cells of the anterior lobe of the mpituitary. Its secretion depends on tonic inhibition by the prolactin inhibitor PIF, produced in the hypothalamusrz, which is sensitive to dopamine, among other things.

Dopaminergic receptors inhibitors (such as metaclopramide) stimulate PRL secretion. TRH, VIP and serotonin are also stimulants. Prolactin is secreted pulsatilely throughout the day, reaching its highest concentration at night.

Increased concentrations of PRL are observed during sleep, as well as during high physical or mental exertion, during pregnancy, and in the postpartum period. Physiologically, its action is to initiate and sustain lactation in the postpartum period and to regulate the function of the reproductive glandss in both sexes.

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High PRL levels with no or few clinical symptoms may indicate macroprolactinemia. Macroprolactin (BB-PRL) is a large complex of prolactin bound to immunoglobulin G (IgG) or, less commonly, to an aggregate of prolactin molecules.

Because of its large molecule (more than 150 kDa), macroprolactin has more difficult access to tissue receptorsso it binds less well to them, thus exerting little biological effect with preserved immunoreactivity (it is detected by standard methods to determine PRL levels). To date, the cause of antibodies to prolactin has not been clarified.

It is not known whether it is a defect in the immune system or a slightly altered PRL molecule. The disorder affects about 20% of casesof idiopathic hyperprolactinemia and occasionally (in about 2% of casesof cases) may accompany pituitary adenomas.

It is a common disorder of prolactinemia

Intriguing about this pathology is the fact that a large percentage of these cases are either asymptomatic or sparsely symptomatic and are often detected incidentally.