Prolactin

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PROLACTIN PRODUCING ADENOMA

Most common pituitary tumor

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Prolactin

Synthesized in lactotropes 20% of anterior pituitary cells

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Common precursor cell

For lactotropes and somatotropes

May give rise to a tumor secreting both prolactin and growth hormone

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When does prolactin synthesis begin?

Fetus 12 weeks gestation

4 weeks after GH

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Prolactin secretion

Pulsatile Peak serum prolactin levels

Between 4:00 and 6:00 A.M

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Circulating half-life of prolactin

50 minutes

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Dopamine

Prolactin inhibitory factor Suppresses prolactin release

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Pituitary stalk section

Mass lesions at the skull base Prolactin hypersecretion

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Primary action of prolactin Induce and maintain lactation Clinical problems

Effect of prolactin on gonadal function

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Hyperprolactinemia

Anovulation

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Hypersecretion of prolactin Infertility

Gonadal dysfunction

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Prolactin

Suppresses hypothalamic GnRH Inhibit the release of LH and

FSHImpair gonadal steroidogenesis Hypoestrogenism and anovulation

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Prolactin

Ensure that maternal lactation is sustained

Not interrupted by pregnancy Decreases reproductive function Suppress sexual drive

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Increase calcium absorption Gastrointestinal calcium

absorption is increased Bone calcium is mobilized Hyperprolactinemia

Increases bone loss May cause osteoporosis

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Males

Decreased spermatogenesis Reduced LH secretion

Low testosterone levels Decreased spermatogenesis Decrease libido

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Which of the following is not a prolactin action?

A. Induce and maintain lactation B. AnovulationC. Decreased spermatogenesis

D. Increase calcium absorption E. Pubertal mammary

development

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Answer

Pubertal mammary development Prolactin is not essential Requires GH

Action mediated by IGF-I

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What is the most common pituitary hormone hypersecretion syndrome in males?

A.AcromegalyB. Cushing’s diseaseC. HyperprolactinemiaD.Diabetes

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Answer

Hyperprolactinemia Both males and females

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