Can You Live Without a Thymus? Exploring the Lifelong Health Consequences

October 2, 2025 •

3 min read

While the thymus has long been considered expendable in adults, a groundbreaking 2023 study published in the New England Journal of Medicine found that adults who had their thymus removed had a significantly higher risk of all-cause mortality and cancer. The answer to can you live without a thymus? is complex and depends heavily on age and life circumstances.

Quick Summary

The ability to live without a thymus depends heavily on age; it is crucial for infants but has newfound implications for adult health. Recent studies reveal unexpected long-term health consequences like increased risks of cancer and autoimmune diseases after thymus removal in adults, challenging prior assumptions.

Key Points

Age is critical: In infants, a functioning thymus is essential for survival; its absence leads to life-threatening immunodeficiency.
Thymic involution is not the end: Although the thymus shrinks in adulthood, it remains active and continues to produce new T-cells throughout life.
Recent studies reveal new risks: A 2023 study found that adults who underwent thymectomy faced nearly triple the risk of death and double the risk of cancer over five years compared to controls.
Immune dysregulation occurs post-thymectomy: After removal, adults show reduced T-cell diversity and increased levels of pro-inflammatory cytokines, suggesting a lasting impact on immune regulation.
Thymectomy has specific medical uses: Removal is a treatment option for conditions like myasthenia gravis and thymic tumors, but new research is prompting a reevaluation of the risks versus benefits.
Preservation is prioritized when possible: The latest medical perspective suggests that preserving the thymus is important for long-term health and should be considered whenever a thymectomy is not absolutely necessary.

The Thymus: An Immune System Powerhouse in Youth

The thymus is a small gland located in the upper chest that is critical for the development of a healthy immune system, particularly during fetal development and childhood. Its primary function is to serve as a school for T-lymphocytes, or T-cells. While these white blood cells originate in the bone marrow, they travel to the thymus to mature and learn to distinguish between the body's own cells and foreign invaders. This crucial “training” process is most active before birth and throughout early childhood, producing most of the body's T-cell repertoire during this time.

Congenital athymia is a rare and severe condition in which an infant is born without a functional thymus. This leads to a lack of T-cells and the inability to fight off infections. Without treatment, children with congenital athymia often succumb to fatal infections, though new treatments are now available.

Thymic Involution and the Adult Immune System

After puberty, the thymus gland begins to shrink and is gradually replaced by fatty tissue in a process known as involution. This led to the historical assumption that the adult thymus was non-functional and unnecessary. Adults requiring surgical removal of the thymus, known as a thymectomy, were not expected to suffer long-term immune consequences.

However, a landmark 2023 study published in the New England Journal of Medicine challenged this belief. Researchers compared health outcomes in adults who had a thymectomy with a control group. The study found that the adult thymus continues to produce new T-cells, helping maintain T-cell repertoire diversity crucial for immune surveillance.

Thymectomy: Reasons for Removal

A thymectomy is the surgical removal of the thymus gland. While long-term consequences are now being studied, it is still necessary for certain conditions. Common reasons include Myasthenia Gravis, an autoimmune disorder linked to the thymus, and thymoma or thymic cancer.

The Evolving Understanding of Thymectomy Risks

Prior to the 2023 study, risks were considered primarily surgical. However, the study revealed significant long-term health consequences.

Study findings on adults with thymectomy vs. control group:

Increased Mortality: Nearly three times higher risk of all-cause mortality within five years.
Higher Cancer Risk: Doubled risk of developing cancer, often more aggressive and recurrent.
Increased Autoimmunity: Higher risk of developing autoimmune disease post-surgery, associated with altered T-cell counts and pro-inflammatory cytokines.

The Lifelong Impact of Thymus Function

The ability to live without a thymus depends entirely on the age of loss.


Age-Based Comparison of Thymus Removal	Aspect	Thymus Removal in Infancy/Childhood	Thymus Removal in Adulthood
Immune System Impact	Profound T-cell deficiency, severe immunodeficiency.	Reduced new T-cell production, lower T-cell diversity.
Associated Risks	Life-threatening infections.	Increased mortality, cancer, autoimmune diseases.
Treatment Options	RETHYMIC (cultured thymus tissue).	Thymectomy for MG or tumors; risks being reevaluated.
Long-Term Outlook	High survival with treatment.	May be impacted by increased risks.

The 2023 study identified an association, not direct causation, but suggests the adult thymus plays a vital role in immune health and surveillance. This shifts the medical perspective on thymus preservation.

Conclusion: So, Can You Live Without a Thymus?

Yes, but the consequences vary with age. Infants born without a thymus face severe immunodeficiency and are unlikely to survive without treatment. Adults can live without a thymus, but a recent study indicates increased risks of mortality, cancer, and autoimmune diseases. While the immune system can compensate, reduced T-cell diversity may create previously underestimated vulnerabilities. Medical decisions regarding thymectomy must now consider these potential long-term risks alongside the benefits for specific conditions. Preserving the thymus whenever medically feasible is likely beneficial throughout life.

Learn more about the thymus at the National Institutes of Health.

Frequently Asked Questions

The thymus is a small gland that is a vital part of the immune system. It is located in the upper chest, behind the breastbone and between the lungs, and serves as the site for T-cell maturation.

No, an infant cannot survive without a functioning thymus unless they receive a thymic tissue transplant. The thymus is essential for developing a functional immune system, and its absence leads to severe, life-threatening immunodeficiency.

An adult may need a thymectomy to treat conditions like myasthenia gravis, an autoimmune disease linked to the thymus, or to remove thymic tumors, which can be benign or malignant.

Thymic involution is the natural process where the thymus shrinks and is replaced by fatty tissue as a person ages, particularly after puberty. While it becomes less active, it still produces some new T-cells throughout adulthood.

A 2023 study found that adults who had their thymus removed were twice as likely to develop cancer within five years. These cancers were also more frequently aggressive and recurrent compared to those in individuals with an intact thymus.

Recent research suggests a link, finding that adults without prior autoimmune issues who underwent thymectomy had an increased risk of developing an autoimmune disease within five years. This is thought to be related to reduced T-cell diversity and immune dysregulation.

Yes. Treatments like RETHYMIC, an FDA-approved cultured thymus tissue implant, have been developed to help restore immune function and improve survival rates in infants born with congenital athymia.