Hypoprolactinemia can be a cause of failure after childbirth.
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A 29-year-old Turkish woman, gravida 2, para 2, comes to the office because of fatigue, failure to lactate, and amenorrhea for the past two months. She had delivered a healthy baby boy two months ago via spontaneous vaginal delivery, during which she required transfusion of two units of packed erythrocytes. She moved to the US with her family one month ago. Since delivery, she has been unable to breastfeed her child and has yet to resume her menses. Physical examination shows sparse pubic hair. Which of the following factors is the most likely underlying cause behind her condition?
Content Reviewers:Rishi Desai, MD, MPH, Tanner Marshall, MS, Evan Debevec-McKenney, Jahnavi Narayanan
With hypoprolactinemia, hypo- means below, -prolactin refers to the hormone produced by the pituitary gland, and -emia refers to the blood, so hypoprolactinemia means lower than normal prolactin levels in the blood.
Normally, at the base of the brain, there’s a small pea-sized gland called the pituitary gland.
The anterior pituitary - which is the front of the pituitary gland - has a number of different cells, each of which secrete a different hormone.
One group, the lactotroph cells, secrete prolactin.
Apart from milk production, high levels of prolactin also inhibit the release of gonadotropin releasing hormone from the hypothalamus, which results in decreased luteinizing and follicle stimulating hormone levels, which in turn, decreases estrogen levels.
The first way is the most important, and it’s when the hypothalamus secretes a constant stream of dopamine which in this setting is called prolactin inhibiting factor.
Dopamine binds to specific receptors on the lactotroph cells and inhibit the release of prolactin.
If the level of prolactin rises for any reason, then it signals the hypothalamus to release more dopamine, eventually decreasing its own production, a process called negative feedback or feedback inhibition.
The most common cause of hypoprolactinemia is Sheehan’s syndrome, a disorder where lactotroph cells die in a woman that has recently given birth and has postpartum hemorrhage - excessive blood loss during delivery.