Undiagnosed Fever is a common symptom of many diseases and infections. It’s the body’s way of fighting off infections and is often accompanied by chills, sweating, fatigue, and aches. However, in some cases, a fever persists for weeks without an identifiable cause. This condition is known as undiagnosed fever or pyrexia of unknown origin (PUO). When the underlying cause of a fever cannot be identified after thorough evaluation, it can be both confusing and concerning for patients and healthcare providers.
In this blog, we will explore undiagnosed fever, its potential causes, diagnostic methods, and treatment options.
What is Undiagnosed Fever or PUO?
Pyrexia of Unknown Origin (PUO) refers to a fever that lasts for more than three weeks and remains unexplained after at least one week of hospital investigation. PUO is not a disease in itself but a symptom of several possible underlying conditions. It can be caused by a wide range of infections, inflammatory disorders, malignancies, and even rare or unusual conditions.
PUO is typically classified into three types:
- Classic PUO :- This refers to fever lasting for more than three weeks without an identified cause after one week of investigation.
- Healthcare-associated PUO :- Fever associated with hospitalizations, such as infections acquired during a stay.
- Neutropenic PUO :- Fever in patients with reduced white blood cells, often due to chemotherapy or bone marrow disorders.
Common Causes of Undiagnosed Fever
PUO can result from many different underlying conditions. Some of the most common causes include:
- Infections :- Many infections, especially bacterial or viral infections, can lead to prolonged fever. Common infections that may cause PUO include:
- Tuberculosis (TB) :- TB is a chronic bacterial infection that affects the lungs but can spread to other parts of the body.
- Endocarditis :- An infection of the heart’s inner lining.
- Abscesses :- Infections in organs like the liver, brain, or abdomen that form pus-filled pockets.
- Viral Infections :- Hepatitis, HIV, and Epstein-Barr virus (EBV) can cause persistent fevers.
- Autoimmune Disorders :- Conditions such as rheumatoid arthritis, lupus, and vasculitis can lead to prolonged fever as the immune system attacks the body’s own tissues.
- Cancer :- Certain types of cancers, especially lymphoma and leukemia, can present with fever as one of their initial symptoms.
- Drug-induced fever :- Some medications can cause fevers as a side effect. Antibiotics, antihypertensives, and even over-the-counter medications may lead to drug-induced fevers.
- Other Systemic Inflammatory Disorders :- These can include inflammatory bowel diseases, sarcoidosis, and still’s disease.
- Unknown or Rare Causes :- Some cases of PUO remain unexplained after exhaustive testing. Rare genetic disorders, fungal infections, and rare viral infections may be difficult to diagnose.
How Is Undiagnosed Fever?
Diagnosing PUO can be challenging because it involves a wide range of potential causes. The first step in diagnosis is a thorough clinical examination and detailed medical history. Doctors will ask about the duration of the fever, recent travel, exposure to infectious agents, medical history, and any previous illnesses or conditions.
After this initial evaluation, doctors may recommend the following diagnostic tests:
- Blood tests :- A complete blood count (CBC), liver and kidney function tests, and cultures can provide vital clues. Blood cultures may identify bacteria or viruses that are causing the fever.
- Imaging :- X-rays, CT scans, and ultrasounds may help detect underlying infections or abnormalities in the organs that could be causing the fever.
- Biopsy :- In cases where there is a suspected tumor or infection in an organ, a biopsy may be needed to obtain a sample of tissue for examination.
- Bone marrow biopsy :- For certain infections, cancers, or blood disorders, a bone marrow biopsy may be performed.
- Specialized testing :- In some cases, more advanced or rare tests may be necessary. These include specific viral or bacterial tests, genetic screening, and tests for rare conditions.
Treatment of PUO
Once the underlying cause of the fever is determined, treatment will depend on the identified condition. The following treatments may be used:
- Antibiotics :- If an infection is identified, antibiotics or antifungal medications will be prescribed to target the specific pathogen.
- Antivirals :- For viral infections, antiviral medications may be prescribed. In cases of hepatitis, HIV, or influenza, antiviral therapy is essential for controlling the infection.
- Immunosuppressive Therapy :- In cases where PUO is caused by an autoimmune disorder or inflammatory disease, medications to suppress the immune system may be necessary. These include corticosteroids or disease-modifying antirheumatic drugs (DMARDs).
- Cancer Treatment :- If a malignancy is diagnosed, treatment may involve chemotherapy, radiation therapy, or surgical intervention, depending on the type and stage of cancer.
- Supportive Care :- In cases where the cause of PUO is still unknown, doctors may focus on supportive care to manage fever and other symptoms while continuing the diagnostic process.
Tips for Managing PUO
If you are dealing with PUO or prolonged fever, here are some tips for managing the condition:
- Stay Hydrated :- Fever can cause dehydration, so it’s crucial to drink plenty of fluids. Water, oral rehydration solutions (ORS), and electrolyte drinks are all good choices.
- Rest :- Adequate rest helps your body fight infections and manage symptoms better.
- Monitor Symptoms :- Keep track of any changes in symptoms, such as new pains, rashes, or difficulty breathing, and report these to your doctor immediately.
- Follow Medical Advice :- Once a diagnosis is made, adhere strictly to the prescribed treatment and follow-up care.
- Avoid Self-medication :- While over-the-counter medications like fever reducers (acetaminophen or ibuprofen) may help, they should only be used under medical supervision, especially if the cause of the fever remains undiagnosed fever.
Conclusion
Undiagnosed fever or PUO is a challenging medical condition that requires thorough investigation and a methodical approach to diagnosis. With many potential causes ranging from infections to autoimmune disorders, identifying the underlying issue is crucial to proper treatment and recovery. By staying proactive, monitoring symptoms, and working closely with healthcare providers, patients can increase their chances of finding an accurate diagnosis and receiving the appropriate treatment.
