00:00 / 00:00








0 / 7 complete

USMLE® Step 1 questions

0 / 3 complete

High Yield Notes

13 pages



of complete


USMLE® Step 1 style questions USMLE

of complete

A 34-year-old woman, gravida 1 para 1, comes to the clinic due to an inability to breastfeed her baby. She had a spontaneous vaginal delivery of a healthy newborn at full-term 3 weeks ago. The labor was complicated by postpartum hemorrhage secondary to retained products of conception, and she required transfusion with 3 units of packed red blood cells. She has been using formula for feeding, as her milk never “came in.” Review of systems is significant for increased fatigue over the same period, which she attributes to lack of sleep. Temperature is 36.5°C (97°7 F), pulse is 102/min, and blood pressure is 92/76 mm Hg. Physical examination reveals cool, dry skin. Which of the following is the most likely cause of this patient’s condition?

External Links


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.

In men, prolactin decreases testosterone production.

In women, during pregnancy, elevated levels of estrogen stimulate the lactotroph cells to produce large amounts of prolactin which stimulates alveolar cells in the breasts.

In response to prolactin, the alveolar cells divide and enlarge - and once a baby is born, lactogenesis starts - which means that milk is produced.

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.

In women, this can stop ovulation and menstruation, which is why women typically don’t have a menstrual period while breastfeeding.

In women that are not pregnant or breastfeeding, as well as in men, prolactin levels are usually kept in check by the hypothalamus in two ways.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "Harrison's Endocrinology, 4E" McGraw-Hill Education / Medical (2016)
  5. "Hypoprolactinemia and ovarian function**Supported by grants from the Yrjö Jahnsson Foundation and the Paulo Foundation." Fertility and Sterility (1988)
  6. "Aetiology, diagnosis, and management of hypopituitarism in adult life" Postgraduate Medical Journal (2006)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.