Q: For several months I have been running a daily low-grade fever from ½ to 2 degrees, mostly in the early afternoon and for the rest of the day. My primary care doctor has run many tests – urine, blood, cultures, CT scan and an MRI. He is at a loss and suggests we give it up. Can you help?
A: Well, I don’t know. It certainly appears your physician has been fastidious in attempting to determine a cause but perhaps we can hit on something. Temperatures are controlled by the hypothalamus, a portion of the brain that acts like a thermostat. A normal body temperature is about 98.6; a low-grade fever runs about 100 to 101 degrees F; high-grade fevers fall into the 103-104 range. Dangerously high fevers run over 104.
Fever (pyrexia) is a higher-than-normal body temperature that can be caused by a number of illnesses or causes. It’s the body’s response to triggers by fever-producing substances known as pyrogens that tell the hypothalamus when to increase or lower body temperatures. The process is nothing we have to even think about — we shiver or sweat, our blood vessels close or expand – all without us even being aware! Pyrogens include bacteria, viruses, toxins, drugs, even fungi, and many other sources of infection. A temperature can be elevated because of wearing heavy clothing during warmer temperatures, physical activity, having a sinus infection, a UTI, cellulitis, ear infection, anemia, HIV/ AIDs, or the result of taking a specific medication. More serious causes include having inflammatory bowel disease such as Crohn’s (ulcerative colitis), pancreatitis, acute hepatitis, leukemia and other cancers, or a pulmonary embolism.
Illness caused by a virus is the most common cause of fever in adults. Generally speaking, the symptoms of sore throat, cough, muscle aches and pains will improve with time. Antibiotics will not (or should not) be prescribed by a physician, since they are ineffective when treating viruses. Instead, decongestants and over-the-counter fever reducers are more appropriate and a person’s diet should be fortified with extra fluids and electrolyte-containing drinks.
Illness caused by bacteria can affect the entire body with fever, headache neck pain, bronchitis, and more. The lungs, GI system, central nervous system, abdomen, and heart will all present with a myriad of symptoms, depending on the location involved. For example, when the skin is involved, it may react with a rash. Bacterial illnesses can be helped with antibiotics.
Fungal infections can affect any organ system. Biopsy may be required to zero in on the precise location of the infection. Generally speaking, anti-fungal medications should treat the condition successfully.
A fever of unknown origin can be extremely challenging and frustrating to attempt to diagnose. If you have had a white blood cell count, blood/urine/strep cultures, spinal tap, liver function and thyroid testing already, I can understand your physician’s dismay. You might consider asking him if, before he throws in the towel completely, an echocardiogram, endoscopy, PET scan or radionucleotide study might shed some light onto the matter.
You might keep a log of what precedes your daily fevers. Are you working out, eating specific foods, taking supplements or medication, or drinking herbal tea? If there is a pattern you may have your answer. Also, you may consult with an internist at a diagnostic center such as the Mayo Clinic. Give it a try. You’ve got nothing to lose but the fever.
