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Fever. Causes, Laboratory Tests, Treatment and Natural Remedies

Fever, also known as pyrexia, is a temporary increase in body temperature above the normal range. It is a common symptom of many underlying conditions and illnesses, rather than being a disease itself. In most cases, fever is the body's natural response to an infection or inflammation.

Fever is generally defined as a body temperature of 38°C or higher when measured orally. However, the normal body temperature can vary slightly from person to person, and it can also fluctuate throughout the day.

Fever is often caused by infections, such as bacterial, viral, or fungal infections. Common examples include the flu, common cold, urinary tract infections, pneumonia, and gastroenteritis. Other causes of fever include inflammatory conditions like rheumatoid arthritis, certain medications, heatstroke, and some cancers.

Besides an elevated body temperature, other common symptoms of fever may include sweating, chills, headache, muscle aches, weakness, loss of appetite, dehydration, and increased heart rate.

Most fevers resolve on their own within a few days and are not a cause for concern. However, there are situations where medical attention should be sought, such as if the fever persists for more than three days, is accompanied by severe headache or neck pain, difficulty breathing, chest pain, persistent vomiting, or if there are other concerning symptoms.

Causes of Fever

Fever can be caused by a variety of factors. The most common cause of fever is an infection, but there are other potential triggers as well.

Infections: Fever is often a response to infections caused by bacteria, viruses, fungi, or parasites.

  • Respiratory infections such as the flu, common cold, pneumonia, bronchitis, or sinusitis.
  • Urinary tract infections involving the bladder, urethra, or kidneys.
  • Gastrointestinal infections such as gastroenteritis or food poisoning.
  • Skin infections like cellulitis, abscesses, or infected wounds.
  • Sexually transmitted infections such as gonorrhea or chlamydia.
  • Systemic infections like sepsis or meningitis.

Inflammatory conditions: Some inflammatory disorders can cause fever as part of the immune response.

  • Rheumatoid arthritis: an autoimmune disease affecting the joints.
  • Inflammatory bowel disease: such as Crohn's disease or ulcerative colitis.
  • Vasculitis: inflammation of blood vessels.
  • Lupus: an autoimmune disease affecting multiple organs.
  • Temporal arteritis: inflammation of the arteries in the head and neck.

Medications: Certain medications can lead to fever as a side effect. For instance, antibiotics, antihistamines, seizure medications, and some drugs used for treating hypertension may cause fever in some individuals.

Vaccinations: Fever is a common reaction to some vaccines, especially in children. It is often a mild and temporary response as the body builds immunity.

Heat-related conditions: Exposure to excessive heat, such as heatstroke or heat exhaustion, can cause fever along with other symptoms like dehydration.

Cancer: Some cancers, particularly hematologic malignancies like leukemia or lymphoma, can cause persistent or recurrent fever.

Other causes: Fever can also be triggered by factors like trauma, certain autoimmune diseases, allergic reactions, hormonal changes (e.g., thyroid disorders), and some rare genetic disorders.

It's important to remember that fever is a symptom and not a specific disease. Identifying the underlying cause of fever requires a thorough evaluation, considering other symptoms, medical history, and possibly conducting further tests or investigations.

Laboratory Tests for Fever

When evaluating a fever, certain laboratory tests may help identify the underlying cause. The specific tests conducted can vary depending on the patient's symptoms, medical history, and physical examination findings.

Complete Blood Count (CBC): This test provides information about different types of blood cells, including red blood cells, white blood cells, and platelets. An elevated white blood cell count (leukocytosis) may indicate an infection or inflammation.

Blood Cultures: This test involves taking a sample of blood to check for the presence of bacteria or fungi. Blood cultures can help identify bloodstream infections (sepsis) that may be causing the fever. Alternatively, the responsible microbes can be searched for in the blood, using molecular techniques (Opportunistic Microorganism Panel, Molecular Detection).

Urinalysis: This test examines the urine for the presence of infection or inflammation. It can detect urinary tract infections (UTIs) or kidney infections, which are common causes of fever.

Blood Chemistry Panel: This panel includes various tests to assess organ function and electrolyte levels. Abnormalities in liver enzymes, kidney function, or electrolyte imbalances may provide clues to the underlying cause of fever.

Inflammatory Markers: Tests such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) measure levels of inflammation in the body. Elevated levels of these markers can indicate the presence of an inflammatory condition.

Viral Serology: Serologic tests can help identify specific viral infections by detecting antibodies produced by the immune system. Examples include tests for influenza, hepatitis, or HIV.

Imaging Studies: In some cases, imaging tests such as chest X-ray, ultrasound, or CT scan may be ordered to evaluate specific organs or areas of concern, especially when certain infections or inflammatory conditions are suspected.

Functional medicine lab tests are typically used in conjunction with a comprehensive assessment of an individual's health history, lifestyle factors, and symptoms. Functional medicine takes a holistic approach to understanding and treating health issues, including fever. Specific lab tests may be used to assess various aspects of an individual's health and identify underlying imbalances or dysfunctions.

Food Sensitivity Testing (TrophoScan®): Food sensitivities or intolerances can contribute to chronic inflammation and immune system dysregulation, potentially leading to recurring fever. IgG antibody testing may be used to identify immune reactions to specific foods.

Comprehensive Stool Analysis (EnteroScan®): This test examines the composition of the gut microbiome, identifies any pathogenic bacteria, parasites, or yeast overgrowth, and assesses digestive function. Imbalances in the gut microbiota can impact immune system function and contribute to systemic inflammation.

Adrenal Function Testing (AdrenalScan®): Chronic stress or adrenal dysfunction can influence the immune system and contribute to symptoms like fatigue and recurrent fevers. Salivary cortisol testing may be used to evaluate adrenal gland function.

Thyroid Panel: Thyroid imbalances, such as hypothyroidism or hyperthyroidism, can affect the body's temperature regulation and potentially lead to fever-like symptoms. Testing thyroid hormone levels (TSH, T3, T4, reverse T3) and thyroid antibodies can provide insights into thyroid function.

Vitamin and Mineral Testing: Deficiencies or imbalances in certain vitamins and minerals can impact immune function and overall health. Tests for vitamin D, B vitamins, magnesium, zinc, and other nutrients may be considered.

Hormone Panel: Hormonal imbalances, such as those involving sex hormones or the hypothalamic-pituitary-adrenal (HPA) axis, can affect immune function and contribute to symptoms like fever. Hormone testing may include cortisol, estrogen, progesterone, or testosterone levels.

Treatment of Fever

The treatment of fever aims to address the underlying cause while also providing symptomatic relief.

Identify and treat the underlying cause: Since fever is a symptom rather than a condition itself, the primary focus is on identifying and addressing the underlying cause. This may involve treating infections with appropriate antibiotics, antiviral medications, or antifungal drugs. In cases of inflammatory conditions, treatment may involve anti-inflammatory medications or immune-modulating therapies.

Supportive measures

  • Rest: Getting adequate rest allows the body to heal and recover more efficiently.
  • Hydration: Drink plenty of fluids to prevent dehydration, especially if experiencing sweating due to fever.
  • Cool environment: Create a comfortable environment with appropriate ventilation and temperature control.
  • Light clothing and cool compresses: Dress in lightweight, breathable clothing and use cool compresses on the forehead or back of the neck to help reduce body temperature.

Medications for symptomatic relief

  • Paracetamol or nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can help reduce fever and provide relief from associated symptoms like headache, muscle aches, and discomfort. It's important to follow the recommended dosage and consult a healthcare professional, especially in the case of children or if there are underlying medical conditions.
  • Avoid giving aspirin to children or teenagers, as it may increase the risk of a rare but serious condition called Reye's syndrome.

Cool baths: If the fever is high or causing significant discomfort, a tepid bath with lukewarm water can help lower body temperature. Avoid using cold water, as this can cause shivering and potentially raise body temperature.

Seek medical attention when necessary: Most fevers resolve on their own within a few days and are not a cause for concern. However, it's important to seek medical attention if:

  • The fever persists for more than three days or is accompanied by severe symptoms.
  • There are specific concerns about the underlying cause or the individual's medical history.
  • The fever is accompanied by symptoms such as difficulty breathing, chest pain, persistent vomiting, or other concerning signs.

These general recommendations for fever treatment may not be suitable for everyone, especially in specific medical conditions or for individuals with special considerations (e.g., pregnant women, older adults, infants, or those with compromised immune systems).

Natural Remedies for Fever

Some natural remedies may help alleviate fever.

Stay hydrated: Drink plenty of fluids, such as water, herbal teas, and clear broths, to stay hydrated and help regulate body temperature.

Herbal teas: Certain herbal teas, such as chamomile, peppermint, or ginger tea, may help promote relaxation, reduce discomfort, and support the immune system.

Cool compresses: Applying cool compresses or damp washcloths to the forehead, wrists, or back of the neck can provide temporary relief and help lower body temperature.

Proper rest: Adequate rest allows the body to conserve energy and focus on healing. Make sure to get sufficient sleep and take breaks when needed.

Proper nutrition: Consuming a balanced diet rich in fruits, vegetables, whole grains, and lean proteins provides essential nutrients to support the immune system and aid in recovery.

Garlic: Garlic has natural antimicrobial properties and may help support the immune system. Incorporate fresh garlic into meals or consider garlic supplements.

Elderberry: Elderberry has been traditionally used to support immune function. It is available as a syrup, extract, or supplement.

Echinacea: Echinacea is an herb known for its potential immune-stimulating properties. It is available as a supplement or herbal tea.

Essential oils: Certain essential oils, such as peppermint, eucalyptus, or lavender, may provide a soothing effect when used in a diffuser or diluted and applied topically.

Probiotics: Probiotics are beneficial bacteria that support gut health and immune function. Incorporating probiotic-rich foods like yogurt or fermented foods or taking a probiotic supplement may be beneficial.

For all the above supplements, consult a healthcare professional for appropriate use and dosage.

Vasilis J. Sideris
Medical Doctor, Biopathologist (Microbiologist)
Certified Functional Medicine Practitioner, CFMP®

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