What is Fever? Approach To Fever Intro Fever also called Pyrexia, is one of the most common presenting complaints in medical practice. It is defined as a body temperature that is above the normal range,
for that individual, without any physiological cause to it. In other words, temperature raise due to exercise
or menstrual cycle doesn't count as fever. This is usually above 38°C recorded by thermometer. In this case, oral and rectal temperature readings are more accurate than axillary temp. The most important thing to keep in mind is that fever, in it of itself,
is not a disease, but rather a symptom that indicates an underlying disease process. Mechanism of Fever Body temperature is usually set
to its normal range by the hypothalamus, which acts as a sort of thermostat. When the body suffers from certain pathological processes, namely "inflammation", certain chemicals are released by the body, collectively called pyrogens, in other words, of which is interleukin-2. Pyrogens set the thermoregulatory point of the hypothalamus to a higher temperature, thus resulting in fever. The causes of fever can be divided into the broad categories of 1) Infections, which is the most common cause of pyrexia. It can include bacterial, viral, fungal or parasitic infections. 2) Clots 3) Cancers 4) Auto Immune Diseases, and 5) Miscellaneous, which can include things like heat stroke, medications, brain lesions and thyroid storm to name a few. Diagnosing the Cause of Fever We have mentioned 5 categories of diseases that usually result in fever and each category consists of a multitude of possible diseases. In order to narrow down our diagnosis, we need to do a thorough history and examination, and request appropriate lab investigations where relevant. Fever is usually accompanied by other symptoms as well, which may guide the diagnosis of underlying disease. Important questions to ask in history. These can be broadly divided into 2 categories: 1) General Fever Related 2) Review of Systems Fever specific questions include: the duration of fever, the timing of the fever: what time of day is it more prominent?; the character: is it remitting? Or relapsing?; Is it accompanied by chills or rigors? Is there night sweating? Is there weight loss? Is there pain anywhere? Review of systems is a systematic approach to identify accompanying symptoms in other body organs. This is especially important in identifying a possible focus of infection. Ask relevant questions pertaining to each organ system and move from head to toe. So for example, ask about headache? Neck stiffness? Eye pain? Skin rashes or itching? Runny nose? Ear pain or discharge? Coughing? Sputum? Sore throat? Pain on swallowing? Is there difficulty breathing or chest pain? Is there any abdominal pain? Any change in bowel habits? Is there any lymph node enlargement? Any burning sensation while urinating? Any discharge from genitals? Any recent injuries? Any muscle or bone pain? Any recent surgery? Your history will be directed further by the patients' responses and will probably start moving towards a probable diagnosis. Examine the relevant organ system in thorough detail. You mainly need to decide which of the 5 categories does the disease belong to and which organ system is likely affected. For example, acute fever with complaint of burning sensation during urination points to an infection of the urinary tract, whereas chronic low grade fever with anemia and weight loss might be indicating a hematological cancer. Investigations After you have narrowed down your focus in the history and examination by thinking of probable diseases and excluding the unlikely causes, you could advise certain investigations for the patient,
if need be. Remember, it is good clinical practice to avoid unnecessary investigations. Common investigations in fever include; Complete blood count. The white cell count is raised in cases of infection. Liver function tests, urine routine examination, chest X-ray. Some diseases are common in certain areas, so investigations for them could be included, e.g PPD test for Tuberculosis and Viral Antibodies for hepatitis. Cultures for urine, sputum, blood or pus may be needed in cases of bacterial infection to identify the specific pathogen. Red Flags Although a multitude of conditions can cause fever as mentioned before, but some conditions are more serious
than others and require special attention. Always pay special heed to cases of fever with one of the following: 1) Neck stiffness, low GCS or acute neurological deficits. 2) Severe chest pain 3) Rapid weight loss 4) Patient with toxic look 5) Respiratory distress 6) History of any recent surgical procedure 7) Patient who is immuno-compromised 8) High risk behavior including drugs, and sexual promiscuity. 9) History of travel to an endemic area, and 10) if no obvious cause is found
for the fever within 3 weeks in the last case scenario, it becomes known as Pyrexia of unknown origin and requires extensive workup. Febrile Seizures Some children aged 6 months to 5 years may also have associated seizures with an episode of fever. This may greatly worry the patients
and their parents, but they should be reassured that febrile seizures are mostly harmless and do not damage the brain. In case the febrile seizures are not being controlled, refer to pediatricians. Treatment Definitive treatment of the fever lies in treating the underlying cause. In most cases, it is an infection. So the proper anti-microbial drug
should be prescribed. WARNING: Do not use antibiotics without proper prescription or use less than the prescribed period as this leads to antibiotic resistance, resulting in tougher infections. For symptomatic relief of fever, nonsteroidal anti inflammatory drugs, e.g. Ibuprofen or Paracetamol may be used. These provide only temporary relief from fever. Please note that no medications are free from side effects and it is better to avoid taking any medication without any valid reason.
