Common Causes of Persistent Fever and How Tests Can Help

Fever is one of the most common symptoms when the body fights off infections. A person has a fever if their body temperature is above the normal range, around 98.6°F (37°C). The common cause of fever is the flu or a cold, but sometimes the fever may last for several days or recur over weeks. This can be a sign of a more serious condition. In these cases, it’s crucial to consult your doctor to determine the root cause.

The first step is to note down the symptoms and other symptoms of fever. Sometimes, blood tests or other diagnostic tests are necessary to determine the root cause. Once the cause of the issue is identified, your doctor may give you appropriate treatment to reduce the fever. So, what could be causing your persistent fever? Let's understand some of the most common culprits.

Common Causes of Fever

There are several causes of fever that last longer than expected. Let’s go over the most common causes of persistent fever:

Infections

Infections are the most common cause of fevers, including bacteria, viruses, or parasites, that may raise your body temperature to help fight off the invaders. Some infections that can lead to long-term fever include:

• Bacterial Infections could include anything from urinary tract infections (UTIs) to pneumonia or even something more serious like tuberculosis.

• Viral Infections: Flu, COVID-19, or mononucleosis (mono). These viruses can cause prolonged fever while your body fights them off.

• Fungal Infections: Infections like histoplasmosis (a lung infection) or candidiasis (a yeast infection) can also cause a persistent fever.

• Parasitic Infections: Diseases like malaria, or even certain types of worms, can cause recurring fevers, especially in tropical areas.

If an infection causes your fever, it may lead to symptoms like body aches, fatigue, or chills. 

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Chronic Inflammatory Conditions

Certain autoimmune or inflammatory diseases can also lead to persistent fever. The body’s immune system mistakenly attacks healthy tissues, and may lead to inflammation and fever. Conditions such as:

• Rheumatoid arthritis

• Systemic lupus erythematosus (SLE)

• Adult-onset Still's disease

• Inflammatory bowel diseases (IBD) like Crohn’s disease and ulcerative colitis

These conditions can cause low-grade fevers. Inflammatory diseases require long-term management, including medications to control symptoms and reduce inflammation.

Cancer

In some cases, a long-term fever can be related to cancer, such as lymphoma or leukemia. Fever caused by cancer may accompany other symptoms like weight loss, fatigue, or night sweats.

Drug-Induced Fever

Certain medications or drug reactions can cause a persistent fever as a side effect. These are called drug-induced fevers and can occur when the body has an adverse reaction to a specific drug. Some common culprits include:

• Antibiotics like penicillin or sulfonamides.

• Anticonvulsants

• Nonsteroidal anti-inflammatory drugs (NSAIDs)

If you have recently started a new medication and developed a fever, consult your healthcare provider. 

Heat Exhaustion or Heatstroke

If the cause of fever is heat exhaustion or heat stroke, try to cool down the body and focus on rehydration. Fever from heat exhaustion can lead to dizziness, nausea, and confusion. 

Endocrine Disorders

Certain hormonal imbalances can cause persistent fevers. Hyperthyroidism (overactive thyroid) can increase the body’s metabolism and cause elevated body temperature. Adrenal insufficiency (Addison’s disease) is another condition that may cause prolonged fever.

Post-Surgical Fever

If you've recently had surgery, it's common that you might develop a fever. This is often due to the body's healing response, but it can also be a sign of an infection at the surgical site. If the fever persists, consult your doctor to discover the complications, such as infection or blood clots.

Important Blood Tests for Fever

Here are important blood tests that can help you find out the cause of fever- 

• CBC- A CBC test measures the number of RBCs, WBCs, and platelets. It helps to identify whether an infection is present. A high white blood cell count may indicate an infection, while a low count indicates a bone marrow issue or autoimmune disorder.

• ESR- The ESR test measures how quickly red blood cells settle at the bottom of a test tube. It is a marker of inflammation. An elevated ESR may suggest an inflammatory condition, infection, or autoimmune disease.

• CRP- CRP is another marker of inflammation. High levels of CRP can indicate an infection or an inflammatory condition, like rheumatoid arthritis.

• LFT and KFT test- If your fever is suspected of an infection, your doctor might recommend the LFT and KFT tests. 

• Malaria Blood Test- Your doctor might recommend a rapid diagnostic test (RDT) to confirm the presence of the parasite. 

• Widal Test- The Widal test is a blood test that helps diagnose typhoid fever and other enteric fever diseases caused by the bacteria Salmonella typhi. This test detects the presence of specific antibodies in your blood that are produced when your body is infected with these bacteria. 

• Dengue Test- A dengue test is a diagnostic test used to detect the presence of the dengue virus in the body.

How Blood Tests For Fever Can Help?

The blood test for fever helps to diagnose the cause of persistent fever. Here’s how they can help:

• Identify the cause of fever- Blood tests help determine whether an infection, inflammation, cancer, or other condition is causing the fever.

• Early detection of diseases- Blood tests for fever help detect serious health conditions. Early detection allows for quicker intervention, which can improve treatment outcomes.

• Personalized treatment- Identifying the exact cause of a fever helps doctors provide more effective treatment. Your doctor may prescribe medications on time to treat the cause of the fever.

• Monitor disease progression- Blood tests for fever help doctors monitor the progression of chronic conditions like autoimmune diseases.

You May Also read: https://redcliffelabs.com/myhealth/fever/blood-tests-for-fever-check-the-complete-list-and-book-now/

The Takeaway

A persistent fever is a sign that your body is telling you something is wrong. It could be due to various conditions, like infection or chronic diseases. Consult your doctor and take the proper diagnostic tests to identify the cause of persistent fever. However, seek immediate medical attention if you're ever unsure about your symptoms. Your health is worth the attention!