What are examples of signs of a disease?

October 1, 2025 •

4 min read

According to the National Cancer Institute, a medical sign is something observable by a healthcare provider, such as a rash or fever, distinguishing it from a symptom, which is a subjective experience. Understanding what are examples of signs of a disease is a fundamental step toward proactive health management and early detection.

Quick Summary

Signs of a disease are objective, observable indications of an illness, injury, or condition that can be detected by a healthcare professional, such as a fever, swelling, or an abnormal lab result, which are distinct from the subjective experiences a person feels.

Key Points

Objective vs. Subjective: A medical sign is an objective, observable indicator of disease (e.g., a rash), while a symptom is a subjective feeling reported by the patient (e.g., pain).
Local Signs: Examples of localized signs include visible lumps, swelling, rashes, and abnormal sounds in a specific area like the lungs.
Constitutional Signs: Systemic or constitutional signs affect the entire body, such as persistent fever, unexplained weight loss, and chronic fatigue.
Diagnostic Signs: Many signs are only revealed through medical tests, such as abnormal blood test results, high blood pressure, or irregularities on an X-ray.
Early Detection: Recognizing signs of disease, even in the absence of obvious symptoms, is crucial for early detection and can significantly improve treatment outcomes.
Regular Check-ups: Routine physical exams and screenings are vital because they allow healthcare providers to look for signs that the patient might not feel or notice.

What is a Medical Sign?

In medical terminology, a 'sign' is an objective, externally observable indication of a medical condition. Unlike symptoms, which are a patient's subjective experience (like pain or fatigue), a sign can be detected by someone else, typically a healthcare provider, through a physical examination, medical tests, or imaging studies. These objective markers are critical diagnostic tools that help physicians build a comprehensive picture of a person's health.

Local Signs of Disease

Local signs are those confined to a specific area of the body, indicating a problem in that particular region. These can often be identified through a physical inspection.

Examples of Local Signs

Rash or Skin Discoloration: A localized rash can be a sign of anything from an allergic reaction to an infectious disease like measles or Lyme disease. Changes in skin color, such as yellowing (jaundice) or a bluish tint (cyanosis), are also significant local signs.
Swelling or Edema: Localized swelling, especially around an injury or infection site, is a classic sign of inflammation. This can also indicate issues with fluid retention, circulation, or injury.
Visible Lumps or Masses: A palpable lump in a certain area, such as the breast, lymph nodes, or a joint, is a sign that requires further investigation.
Audible Sounds from Lungs: Wheezing or crackling sounds detected by a doctor with a stethoscope are objective signs of a respiratory issue.
Abnormal Reflexes: An exaggerated or absent reflex response, such as in the patellar reflex (knee-jerk), can indicate neurological damage.

Systemic or Constitutional Signs of Disease

Systemic or constitutional signs are those that affect the entire body, rather than a single organ or location. They are often non-specific but are important indicators that something is amiss on a larger scale.

Examples of Constitutional Signs

Fever: An elevated body temperature is one of the most common signs of a systemic infection, as it indicates the body's immune response is activated.
Unexplained Weight Loss: Losing a significant amount of weight without trying can be a sign of many systemic conditions, including chronic infections, metabolic disorders, and cancer.
Fatigue: Persistent, unexplained fatigue that is not relieved by rest is a prominent sign associated with numerous chronic diseases, from autoimmune disorders to cancer.
Malaise: A general feeling of discomfort, illness, or unease that is often difficult for a person to describe but can be observed through their lack of energy or change in demeanor.
Night Sweats: Drenching night sweats can be a sign of certain infections, hormonal imbalances, and some types of cancer.

Diagnostic Signs from Medical Tests

Many of the most telling signs of a disease are not visible externally but are revealed through diagnostic tools and laboratory analysis. These provide crucial data for a definitive diagnosis.

Examples of Diagnostic Signs

Abnormal Blood Test Results: Deviations in a complete blood count (CBC), such as unusually low hemoglobin or high white blood cells, can be signs of conditions like anemia or leukemia. Elevated blood sugar is a sign of diabetes.
Abnormal Imaging Results: Findings on a mammogram, X-ray, MRI, or CT scan, such as a tumor, fracture, or other structural abnormality, are clear diagnostic signs.
High or Low Blood Pressure: As a key vital sign, abnormal blood pressure readings can indicate underlying cardiovascular or kidney problems.
Irregular Heart Rate: An unusually rapid, slow, or irregular heart rhythm can be a sign of a cardiac issue.
Pathological Findings from a Biopsy: Examination of tissue can reveal the presence of a specific disease, such as cancer.

Comparing Signs and Symptoms

To reinforce the distinction between signs and symptoms, consider the following comparison. Understanding the difference is crucial for effective communication with a healthcare provider and for correctly interpreting medical information.


Feature	Medical Sign	Medical Symptom
Observer	Can be observed or measured by an outsider, like a doctor or family member.	Experienced and described only by the individual themselves.
Nature	Objective and factual.	Subjective and personal.
Examples	Fever measured by a thermometer, a visible rash, high blood pressure reading, abnormal liver enzymes in a blood test.	Nausea, headache, generalized pain, fatigue, ringing in the ears.
Verification	Can be confirmed with tests, instruments, or observation.	Relies on the patient's report and description.

The Importance of Recognizing Signs

Spotting the objective indicators of illness is a critical part of healthcare. While a patient may not feel unwell, a routine check-up might reveal a silent condition like high blood pressure, which could otherwise cause serious damage over time. Regular screenings and check-ups allow medical professionals to look for these asymptomatic signs that aren't visible or obvious. Ultimately, recognizing and acting on these signs, whether they are constitutional, local, or detected through testing, can lead to early diagnosis and a better prognosis. It is important to pay attention to your body and consult a healthcare professional if you notice any unusual or persistent changes.

For more detailed medical information and resources, you can consult authoritative health sites like the National Institutes of Health.

Conclusion

Understanding the distinction between signs and symptoms of disease is fundamental for effective healthcare. Signs are the measurable, objective evidence of a medical condition that a clinician can detect, such as a rash, fever, or an irregular heartbeat. By being vigilant for both subtle local signs and broader systemic indicators, and by engaging in regular check-ups that can reveal diagnostic signs through testing, individuals can take an active role in their health. Early detection through signs is often the first and most critical step toward timely and successful treatment.

Frequently Asked Questions

A sign is an objective, measurable indication of a disease that can be observed by a doctor, like a fever or a rash. A symptom is a subjective feeling experienced and reported by the patient, such as a headache or nausea.

Yes. Many diseases can be asymptomatic, meaning they show no noticeable symptoms to the patient, especially in their early stages. Conditions like high blood pressure can be present for years, causing damage, before symptoms appear.

Fever is a sign because it is an objectively measurable elevated body temperature. Unexplained weight loss is also considered a sign, as it can be measured and points to an underlying constitutional issue.

Common signs of an infection include fever, redness, swelling, warmth around a wound, and unusual drainage. A doctor may also see an increased white blood cell count in a blood test.

Diagnostic test results are considered signs because they provide objective evidence of a condition that can be measured and confirmed. For example, an abnormal result on a blood test or an MRI is a measurable sign of an underlying issue.

It is very important. While many changes may be harmless, informing your doctor about new or persistent issues—no matter how subtle they seem—helps them gather information to connect signs and symptoms, leading to an accurate diagnosis.

Yes. Some signs can indicate an increased risk for developing a disease later. For instance, high triglycerides found in a blood test can be a sign of higher risk for developing diabetes or heart disease.