Endocrinology

Biology and Diagnosis: Why the Pituitary Fails

At a Glance

Sheehan syndrome occurs when severe bleeding during childbirth starves the enlarged pituitary gland of oxygen, causing irreversible tissue death. This damage often appears as an "empty sella" on an MRI and requires lifelong hormone replacement therapy to manage.

Understanding why Sheehan syndrome happens requires looking at how the body changes during pregnancy. Your pituitary gland, located at the base of your brain, is the “control center” for your hormones. During pregnancy, this gland is under intense pressure to perform, which makes it uniquely vulnerable to damage ^[1]^[2].

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The “Perfect Storm” of Pregnancy Biology

During pregnancy, your pituitary gland grows significantly—sometimes nearly doubling in size—to produce the hormones needed to support a growing baby ^[1]. However, while the gland gets much larger, the network of blood vessels that supply it does not grow at the same rate ^[3].

This creates a high-demand, low-supply situation. The anterior (front) part of the pituitary is especially sensitive because it relies on a low-pressure blood system ^[3]. When a woman experiences a postpartum hemorrhage (severe bleeding during birth), her blood pressure drops sharply. In this “perfect storm,” the enlarged, oxygen-hungry pituitary gland is starved of blood flow, leading to ischemic necrosis—the death of the gland’s tissue due to lack of oxygen ^[4]^[2].

The “Empty Sella”

If you have had an MRI, you may have seen the term empty sella turcica in your report. The sella turcica is the small, bony pocket in the skull where the pituitary gland sits.

In Sheehan syndrome, after the pituitary tissue dies (necrosis), the body gradually absorbs the dead cells ^[5]. Over time, the gland shrinks or flattens against the floor of the bony pocket. On a scan, the pocket looks like it is filled with fluid rather than a solid gland, leading to the “empty” appearance ^[6]^[4]. This is a key piece of evidence doctors use to diagnose the condition years after the original event ^[6].

Sheehan Syndrome vs. Lymphocytic Hypophysitis

It is important to distinguish Sheehan syndrome from another pregnancy-related pituitary condition called lymphocytic hypophysitis. While both can cause hormone shortages, they are biologically very different:

Feature	Sheehan Syndrome	Lymphocytic Hypophysitis
Cause	Lack of blood flow (Ischemia) after heavy bleeding ^[2].	An autoimmune attack where white blood cells invade the gland ^[7].
Timing	Triggered by a birth event (hemorrhage) ^[5].	Can happen during late pregnancy or without any bleeding ^[5].
MRI View	Often shows a flattened or empty sella (in chronic cases) ^[6].	Often shows an enlarged or swollen pituitary that can look like a tumor ^[8].
Recovery	Damage is usually irreversible; lifelong hormone therapy is needed ^[5].	Sometimes resolves on its own or with steroid treatment ^[9].

The Role of Anatomy

Recent research suggests that the shape of your skull might play a role in your risk. Women with a naturally smaller sellar volume (a tighter bony pocket) may be more prone to Sheehan syndrome ^[10]. If the pituitary gland swells during pregnancy but is “trapped” in a small space, the pressure can further cut off blood flow during a hemorrhage, making tissue death more likely ^[10].

You may wonder if this physical trait means the condition is genetic. Sheehan syndrome itself is not an inherited disease, and having a small sella does not necessarily mean your daughter is at high risk of the same event.

Common questions in this guide

Why does heavy bleeding during childbirth cause Sheehan syndrome?

During pregnancy, your pituitary gland grows larger and requires more oxygen. Severe bleeding during birth causes a sharp drop in blood pressure, depriving this enlarged gland of blood flow. This lack of oxygen causes the pituitary tissue to die.

What does an 'empty sella' mean on an MRI?

The sella turcica is the small bony pocket in your skull that holds the pituitary gland. In Sheehan syndrome, the damaged pituitary tissue shrinks or is absorbed by the body, making the pocket look fluid-filled or 'empty' on an MRI scan.

Is Sheehan syndrome the same as lymphocytic hypophysitis?

No, they are biologically different. Sheehan syndrome is caused by a lack of blood flow following severe bleeding during childbirth. Lymphocytic hypophysitis is an autoimmune condition where the body's immune system mistakenly attacks the pituitary gland.

Does skull anatomy or a small sella increase the risk of Sheehan syndrome?

Having a naturally smaller bony pocket (sellar volume) may increase the physical pressure on a swollen pituitary gland during childbirth, making damage more likely if you hemorrhage. However, Sheehan syndrome itself is not an inherited disease.

Curated prompts to bring to your next appointment.

1.Did my MRI show an 'empty sella,' and how does that correlate with the timing of my delivery?
2.Since my symptoms didn't start until years later, how can we be sure this is Sheehan syndrome and not an autoimmune condition like lymphocytic hypophysitis?
3.If my sella turcica is small, does that explain why the damage was so extensive during my hemorrhage?
4.Do my hormone levels suggest damage to the posterior pituitary as well, or just the anterior portion?

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References (10)

1
Dynamic Expression of Imprinted Genes in the Developing and Postnatal Pituitary Gland.
Scagliotti V, Costa Fernandes Esse R, Willis TL, et al.
Genes 2021; (12(4)) doi:10.3390/genes12040509.
PMID: 33808370
2
Treatment-triggered onset and diagnosis of Sheehan syndrome in a multiple myeloma patient.
Bing X, Peifang L
Cancer reports (Hoboken, N.J.) 2019; (2(4)):e1171 doi:10.1002/cnr2.1171.
PMID: 32721123
3
Pituitary apoplexy: pathophysiology, diagnosis and management.
Glezer A, Bronstein MD
Archives of endocrinology and metabolism 2015; (59(3)):259-64.
PMID: 26154095
4
Using the brain to heal the heart: A case discussion and review of panhypopituitarism-induced chronic heart and kidney failure.
Abate EG, Sharma S, Barsukova Y, Goswami R
JHLT open 2024; (5()):100111 doi:10.1016/j.jhlto.2024.100111.
PMID: 40143910
5
Acute pituitary disease in pregnancy: how to handle hypophysitis and Sheehan's syndrome.
Honegger J, Giese S
Minerva endocrinologica 2018; (43(4)):465-475 doi:10.23736/S0391-1977.18.02814-6.
PMID: 29463076
6
A Rare Case of Sheehan Syndrome With Cardiac Tamponade.
Zain A, Sivakumar A, Akah O, et al.
Cureus 2022; (14(4)):e24329 doi:10.7759/cureus.24329.
PMID: 35607582
7
Post-partum hypoglycemia and hypothermia as first manifestations of lymphocytic adenohypophysitis: A case report.
Koyama S, Okuno K, Naoi H, et al.
The journal of obstetrics and gynaecology research 2016; (42(4)):467-70 doi:10.1111/jog.12930.
PMID: 26786534
8
Other Pituitary Conditions and Pregnancy.
Chanson P
Endocrinology and metabolism clinics of North America 2019; (48(3)):583-603 doi:10.1016/j.ecl.2019.05.005.
PMID: 31345525
9
Clinical presentation and magnetic resonance imaging characteristics of lymphocytic hypophysitis: a systematic review with meta-analysis.
Ju JS, Cui T, Zhao J, et al.
Archives of medical science : AMS 2023; (19(4)):976-986 doi:10.5114/aoms/144628.
PMID: 37560735
10
Sella Turcica Size in Women with Sheehan Syndrome-A Case-Control Study.
Laway BA, Sharma A, Choh NA, et al.
Indian journal of endocrinology and metabolism 2023; (27(5)):431-435 doi:10.4103/ijem.ijem_316_22.
PMID: 38107734

This page explains the biology and diagnosis of Sheehan syndrome for educational purposes only. Always consult your endocrinologist or healthcare provider for professional medical advice regarding your specific symptoms and MRI results.

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