The half-moon shape at the base of your fingernail is known as a lunula. Lunulae cover the bottom of your nail, just above your cuticle.

Quick Facts About Lunala

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DefinitionThe lunula is the visible part of the nail matrix, appearing as a whitish, crescent-shaped area at the base of some fingernails and toenails
Normal AppearanceTypically, the lunula is whitish and is most prominent on the thumb. It may not be visible on every finger
FunctionIndicates the health of the nail matrix, which is responsible for producing new nail cells
Common ChangesChanges in color, size, or shape of the lunulae can signal various health issues
Health IndicatorAbsence or Reduced Size: May suggest malnutrition or anemia; Large Lunulae: Can indicate cardiovascular issues or high blood pressure; Discolored Lunulae: May point to systemic issues like liver problems (yellow) or diabetes (reddish)
Nail ProblemsOnychomycosis (Fungal Infection): Discoloration and thickening of nails; Psoriasis: Pitting, discoloration, and thickening of nails; Trauma: White spots (leukonychia) or splitting of the nail; Systemic Diseases: Changes in lunulae can indicate broader health issues
MisconceptionsYellow lunulae are not always a sign of liver disease; nail polish is not the sole cause of yellowing
DiagnosisObservation of lunulae during physical examination, alongside other symptoms and medical history
TreatmentDepends on the underlying cause; can range from dietary changes and supplements to medical treatment for systemic diseases
PreventionMaintaining overall health through a balanced diet, proper nail hygiene, and monitoring for any changes in nail appearance
Special ConsiderationsChildren and elderly may have less prominent lunulae naturally. Variations in lunulae among different ethnic groups are also common
Research & StudiesOngoing studies investigate the link between lunulae changes and early detection of systemic diseases, potentially serving as non-invasive indicators of health status
When to See a DoctorIf there are significant changes in the lunulae, such as color change or shape distortion

Lunulae are part of your nail matrix. The matrix refers to the tissue just beneath your nail. It contains nerves, lymph, and blood vessels. It also produces the cells that become the hardened nail plate, which is what you see.

Although everyone has a nail matrix, not everyone will see or have a lunula on each nail. Those who do have a lunula may notice that they vary in appearance across each nail.

Read on to learn more about what these lunalae look like, when their appearance or absence could be cause for concern, and when to see your doctor.

 

An Overview of the Lunala

Lunula - Healthsoothe

The lunula, or lunulae (pl.) (derived from a Latin word meaning 'little moon'), is the crescent-shaped whitish area of the bed of a fingernail or toenail.1https://en.wikipedia.org/wiki/Lunula_(anatomy)

In humans, it appears by week 14 of gestation and has a primary structural role in defining the free edge of the distal nail plate (the part of the nail that grows outward).

The video below expatriate on the lunala's significance:

YouTube video

 

The Appearance of the Lunala

It is located at the end of the nail (that is closest to the skin of the finger), but it still lies under the nail. It is not actually white but only appears when it is seen through the nail.

Outlining the nail matrix, the lunula is a very delicate part of the nail structure. If one damages the lunula, the nail will be permanently deformed. Even when the totality of the nail is removed, the lunula remains in place and is similar in appearance to another smaller fingernail embedded in the nail bed.

In most cases, it is half-moon-shaped and has unique histologic features. Examinations concluded that the lunula is an area of the loose dermis with lesser-developed collagen bundles. It appears whitish because a thickened underlying stratum basale obscures the underlying blood vessels.

The lunula is most noticeable on the thumb; however, not everyone's lunulae are visible. In some cases, the eponychium may partially or completely cover the lunula.

Lunula Function (Nail Problems)

The Importance of the Lunala

The lunula’s location on the newest part of the nail allows assessments to be made about one’s health. In some cases, its absence may indicate an underlying health problem. Some examples of such problems are malnourishment, anemia, kidney failure, and heart disease.

 

What does a Healthy Lunulae look like?

What Does A Healthy Lunula Look Like - Healthsoothe

Healthy lunulae are usually a whitish color and take up a small portion of the bottom of your nail. They’re usually most visible on your thumb.

You may notice that they appear smaller on your pointer finger, gradually shrinking in size until you reach your pinkie where they may be barely visible.

 

What if your Lunulae Change Color?

Sometimes, the appearance of your lunula or overall nail can be a sign of an underlying condition.

Check the table below to know what a lunalae color change indicates;

Lunulae Color Meaning - Healthsoothe

 

What Causes Abnormal Coloring of the Lunulae?

Lunula Discoloration - Healthsoothe

Here are some of the most common reasons for abnormal lunulae:

Tetracycline medications are antibiotics that are usually used to treat acne and skin infections. Extended use may cause your lunulae to turn yellow.

  • Diabetes

Pale blue lunulae may be a sign of undiagnosed or uncontrolled diabetes. This is a chronic, lifelong condition that affects the body’s ability to control blood sugar.

  • Excessive fluoride ingestion

Taking in too much fluoride, like that found in toothpaste, can turn the lunulae brown or black.

  • Silver poisoning

Blue-gray lunulae may be a sign of silver poisoning.

  • Yellow nail syndrome

This condition typically produces thick, slow-growing nails. The middle of your nail may begin to rise, causing the lunulae to disappear completely. Your entire nail will take on a yellow appearance.

It isn’t clear what causes this syndrome, but it may be tied to:

  • chronic sinusitis
  • pleural effusion
  • recurrent pneumonia
  • lymphedema
  • rheumatoid arthritis
  • immunodeficiency disorders
  • Terry’s nails

This condition causes the bulk of your nail to appear white, completely erasing the appearance of the lunula. It’s characterized by a pink or red band of separation near the arc of your nails. Although it can happen on one finger only, it usually affects all fingers.

In older adults, this condition is usually a natural sign of aging.

In some cases, it may be a sign of:

  • diabetes
  • liver disease
  • kidney failure
  • congestive heart failure
  • Wilson’s disease

This is a rare inherited disorder that occurs when too much copper accumulates in your organs. It’s known to cause blue lunulae.

  • Severe renal disease

The portion of your nail containing the lunula may turn white, sometimes creating a nail that’s half-brown and half-white. This is sometimes called half-and-half nails and may be a sign of renal disease.2healthline

  • Chronic renal failure

People who experience chronic renal failure may produce more melanin, which can cause your nail bed to turn brown.

  •  Heart failure

If your lunula turns red, it may be a signal of heart failure.

 

What Does it Mean if your Lunulae are Small or Missing?

Small or missing lunulae usually aren’t usually a cause for concern. They’re usually just hidden underneath the cuticle or skin at the base of your finger.

In some cases, missing lunulae may be a result of trauma or a sign of:

  • anemia
  • malnutrition
  • depression

If you’re experiencing other unusual symptoms, such as fatigue or overall weakness, make an appointment to see your doctor. They can perform a physical exam to help diagnose the cause of your symptoms and advise you on the next steps.

 

What if your Lunulae are Large or Misshaped?

Misshaped Lunala - Healthsoothe

Researchers don’t know what causes the lunula to take up a significant portion of the nail.

Some reports suggest that lunulae may signal issues with the cardiovascular system, heartbeat disruption, and low blood pressure.

Unscientific theories claim that large lunulae may be common in athletes and people who engage in lots of physical activity.3Guglielmi, Giuseppe; Kuijk, Cornelis Van; Genant, Harry K (2001). Fundamentals of hand and wrist imaging. ISBN 978-3-540-67854-0. This may be due to the bodily stress associated with high-impact activities, but there is currently no research to back up these claims.

 

When to See the Doctor

Discolored or missing lunulae usually aren’t usually a cause for concern. But if you notice changes in your nail appearance and are experiencing other unusual symptoms, make an appointment to see your doctor.

You should seek immediate medication attention if your hands and feet are also turning blue. This could be a sign of cyanosis, a condition that results from poor circulation or inadequate oxygenation of your blood.

Your doctor can assess your symptoms and advise you on treatment options. Treating the underlying condition will usually restore your nail appearance and improve your overall well-being.

 

Conclusion

The lunula is the visible portion of the distal nail matrix that extends beyond the proximal nail fold. It is white, half-moon-shaped, appears by week 14 of gestation, and has unique histologic features. The lunula has a primary structural role in defining the free edge of the distal nail plate.

Feel free to contact us at contact@healthsoothe.com if you have further questions to ask or if there’s anything you want to contribute or correct to this article. 

You can always check our FAQs section below to know more about the lunala. 

Frequently Asked Questions About the Lunala

Skin color and other factors may make the lunulae more or less visible. Because the lunula comprises the newest portion of the nail, it can provide clues about a person's health. The absence of lunulae does not always indicate a serious health problem, but it is a good idea to discuss the issue with a doctor. Lunula anomalies include changes..... Read More »
Small or missing lunulae usually aren't a cause for concern. They're usually just hidden underneath the cuticle or skin at the base of your finger. In some cases, missing lunulae may be a result of trauma or a sign of: anemia. Lunula dyschromias can be confluent or spotted or can be characterized by longitudinal colored bands that traverse the lunula...... Read More »

Systemic conditions may be associated with an enlarged lunula. These include hyperthyroidism, leprosy, and scleroderma. Investigators evaluated 39 patients with connective tissue diseases including dermatomyositis, scleroderma, Sjogren's syndrome, and systemic lupus erythematosus.

Absent lunula can progressively develop in a person who previously had a normal-sized lunula and can be associated with various systemic disorders. In this case-control study we hypothesised that absent lunula is associated with depression.

The lunula looks white because the epidermis is thicker beneath the matrix and it blocks the pink color from the blood vessels below.

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Additional resources and citations

  • 1
    https://en.wikipedia.org/wiki/Lunula_(anatomy)
  • 2
    healthline
  • 3
    Guglielmi, Giuseppe; Kuijk, Cornelis Van; Genant, Harry K (2001). Fundamentals of hand and wrist imaging. ISBN 978-3-540-67854-0.
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