Low-Grade Fever: Causes and Concerns in Family Medicine

Q: Low-Grade Fever: Causes and Concerns in Family Medicine

Dear Ms. Amy： 1. Humans possess physiological mechanisms to regulate and maintain core body temperature. When there is a need to release excess heat, the body cools down by increasing blood circulation to the skin and sweating. Conversely, to conserve internal

Temperature issues

Hello Doctor: My condition started on the 7th of this month, when I felt a sensation of body heat for about four days (I didn't take my temperature, as I have experienced this occasionally before, and it has never been a real fever; just a warm neck, along with some mild headache, but no other discomfort).
After those four days, I returned to normal.
However, on the 18th-19th of this month: (1) In the evening, I again felt warm, and my ear temperature reached a maximum of 37.6°C.
(2) On the 20th: I still felt warm, and in the morning at home, I measured a temperature of 37.8°C, starting to feel a bit unwell, with slight diarrhea, headache, and fatigue, but no other symptoms.
I rested lying down, and by the afternoon, my temperature dropped to 37.1°C, fluctuating between 37-37.5°C.
(3) On the 21st: I woke up feeling the same discomfort as the previous day, like having a cold, with fatigue and warmth, but still no real fever, fluctuating between 37-37.6°C.
(4) On the 22nd: I started to feel better, and the cold-like symptoms seemed to have disappeared, with my temperature ranging from 36.7-37.4°C.
After that, my temperature returned to normal.
I would like to ask the doctor: 1.
On the 21st, I had blood tests, urine tests, and a PCR test, and the doctor said everything was normal with no infection, and the PCR was negative.
Does this mean that the warmth I felt that week was considered low-grade fever? I am very worried that the blood and urine tests showed no infection, which might imply that it is not a cold.
Why then did I still experience sudden warmth that week...
My body doesn't seem to have any other unusual symptoms, or should I get further tests done? Do you think this is normal, or am I overthinking it? 2.
I started my menstrual period on the 22nd; could this warmth be related to my menstrual cycle? Thank you, doctor.
I have been under a lot of mental stress during this period, and I know it must be even harder for you! Thank you!

Amy, 30~39 year old female. Ask Date: 2022/04/23

Dr. Xiao Yongxun reply Family Medicine

Dear Ms.
Amy:
1.
Humans possess physiological mechanisms to regulate and maintain core body temperature.
When there is a need to release excess heat, the body cools down by increasing blood circulation to the skin and sweating.
Conversely, to conserve internal heat, the body reduces blood circulation to the skin to minimize heat loss or generates heat through shivering reflexes and peripheral vasoconstriction.
2.
The most common cause of fever is infection; however, other factors such as autoimmune diseases, tumors, trauma, medications, pregnancy, and ovulation may also contribute.
3.
Your situation may indicate a mild cold or simply a normal physiological response.
Since your symptoms have resolved, it would be advisable to observe for a few more days.
If you have further concerns, please discuss them with your attending physician.

Reply Date: 2022/04/23

More Info

Low-grade fever, defined as a body temperature between 100.4°F (38°C) and 102.2°F (39°C), can be a perplexing symptom for many patients. It often raises concerns about underlying health issues, especially when it persists or recurs. In your case, the episodes of feeling warm, along with recorded temperatures reaching up to 37.8°C (100°F), suggest that you may indeed be experiencing low-grade fever.

There are several potential causes for low-grade fever, which can range from benign to more serious conditions. Common causes include:
1. Infections: Viral infections are often the culprits behind low-grade fevers. Even if your blood tests and PCR results came back negative, it’s important to note that some viral infections may not be detectable at the time of testing. Additionally, mild infections can sometimes resolve quickly, leading to fluctuating temperatures.

2. Inflammatory Conditions: Conditions such as autoimmune diseases can cause low-grade fevers as the body’s immune system reacts to perceived threats.
3. Hormonal Changes: In women, hormonal fluctuations related to the menstrual cycle can lead to variations in body temperature. It’s not uncommon for women to experience slight increases in body temperature during ovulation or menstruation due to hormonal changes.

4. Stress and Fatigue: Psychological stress and physical fatigue can also manifest as low-grade fever. Stress can impact the immune system and lead to symptoms that mimic illness.

5. Medications: Certain medications can cause fever as a side effect. If you have started any new medications recently, it’s worth considering this possibility.

Regarding your specific questions:
1. Is this low-grade fever concerning? Given that your blood tests and PCR were normal, it is less likely that you have a serious infection. However, if the fever persists or if you develop new symptoms (such as significant fatigue, weight loss, or persistent gastrointestinal issues), further evaluation may be warranted. It’s also important to monitor how you feel overall—if you notice a decline in your general health or if the fever recurs frequently, a follow-up with your healthcare provider is advisable.

2. Could this be related to your menstrual cycle? Yes, it is possible that your low-grade fever could be related to your menstrual cycle, especially since you mentioned that your period started shortly after the fever episodes. Hormonal changes can influence body temperature regulation.

In conclusion, while low-grade fever can be concerning, it is often benign and self-limiting. It’s essential to listen to your body and seek medical advice if symptoms worsen or if you have persistent concerns. Keeping a symptom diary, noting the timing of your fever, associated symptoms, and any potential triggers (like stress or hormonal changes) can be helpful for your healthcare provider in determining the next steps in your evaluation and management.

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