unexplained rise in body temperature

Some people may experience a fever without a clear cause, which may necessitate a visit to the hospital. Let's learn more about this topic in the following article.

Unexplained Fever

Unexplained fever, also known as a fever of unknown origin, is defined as a body temperature of at least 38.3 degrees Celsius that persists for more than three weeks without a clear cause. More details are available in this article:

Causes of Unexplained Fever

There are several causes of fever without illness, including:

Infections such as tuberculosis, endocarditis, sinusitis, osteomyelitis, dental abscess, and abdominal abscess.

Autoimmune diseases such as lupus erythematosus, rheumatism, and inflammatory bowel disease.

Tumors, especially blood cancers such as lymphoma and leukemia. Some medications can cause fever without a known cause, such as pain relievers, anti-rheumatic drugs, anti-epileptic drugs, sedatives, and some antibiotics.

Hyperthyroidism.

Hepatitis is another cause of fever without illness.

Cat scratch fever.

Types of Fever Without a Known Cause: A fever above the normal range indicates an underlying illness. Fever without a known cause can be divided into four main types:

1. Classic or Traditional Fever: This occurs in individuals without chronic illnesses or symptoms, and lasts for at least three weeks. Causes include inflammation, tumors (especially blood disorders like leukemia), or diseases affecting tissues and blood vessels.

2. Hospital-Acquired Fever: This occurs in patients admitted to hospitals for reasons other than fever. Symptoms of fever appear while hospitalized. Causes include:

Inflammation of the blood vessels (phlebitis).

Pulmonary embolism. Inflammation of the intestines and colon caused by a type of bacteria called Clostridium difficile.

Deep vein thrombosis (DVT).

Sinusitis resulting from the use of nasal and tracheal tubes.

3. Fever due to immunodeficiency: This fever is known as fever due to a low white blood cell count and usually occurs in patients undergoing chemotherapy. This is one of the causes of unexplained fever.

4. Fever associated with HIV infection: HIV itself causes fever, and due to its effect on the immune system, the patient is more susceptible to various infections.

Symptoms accompanying fever: A fever above the normal range indicates illness. Fever is accompanied by several symptoms, the most important of which are chills, sweating, and headache. The patient may also experience:

Joint pain.

Fatigue.

Sore throat.

Cough.

Skin rash.

Sinus congestion. Diagnosing Unexplained Fever

Unexplained fever is diagnosed by gathering information from the patient to try to identify the initial cause. The doctor will ask you about: recent travel, any changes in your environment, the presence of pets at your home or workplace, and your family medical history, for example, if there are any hereditary conditions. The doctor will then order the following tests:

1. Physical Examination and Blood Samples

A comprehensive physical examination is performed, including a skin examination to check for jaundice, paleness, or rashes. If the results indicate a problem, the doctor may order further tests.

2. Sample Cultures

Blood, urine, and saliva samples are cultured to detect the presence of bacteria and fungi.

3. Radiographic Imaging

Generally, the appropriate imaging technique is determined based on the location of the pain if it is accompanied by fever. For example, an MRI of the spine is used for back pain, while a CT scan is used if the problem is suspected in the abdomen, chest, or pelvis.

An echocardiogram is used if the doctor hears any changes in the heartbeat, and a positron emission tomography (PET) scan of the whole body is used.

Treatment of Fever Without a Cause

In 50% of cases of fever without a known cause, patients are discharged from the hospital without a specific reason being identified, and often the fever resolves spontaneously.

If doctors identify the cause of the fever, they will treat the underlying cause and thus reduce the fever. Patients can help reduce their fever by doing the following:

Wearing light clothing.

Drinking cool fluids.

Taking a warm bath.

Using fever-reducing medications, such as acetaminophen and ibuprofen.