4 ms·
The whole enterprise of trying to find "a normal" temperature seems silly to me, increasingly after getting two kids with fevers every now and then. We use bot
by kqr 4y ago
The whole enterprise of trying to find "a normal" temperature seems silly to me, increasingly after getting two kids with fevers every now and then.
We use both high-quality ear canal and anal thermometers, and while we have enough statistical grounds to unbias their results compared to each other, there remains significant variance. I.e. if we use an anal or ear canal thermometer makes temperature vary ±0.4 °C.
Then how sloppily you take the measurement with the same thermometer can result in a ±0.2 °C difference for the butt, and ±0.6 °C for the ear canal.
Of course, the time of day we take the temperature can give us a ±0.5 °C difference, and the activity level of the person something like a ±1 °C difference (we don't have as much data on these last ones, naturally.)
And all this is before you bring in the fever! So all of this we consider normal.
Basically, in our experience, anything below 38.4 °C could just as well be caused by any of a number of non-fever conditions at something like a 90 % confidence level, so unless there's a strong prior of fever, a "non-normal" temperature reading on its own is a fairly weak signal.
...which brings me to my final point: the prior ought to strongly affect what counts as normal temperature, but all of this discussion ignores it.
There's also the question whether you prefer false positives or false negatives when it comes to fever detection. My impression is that the medical community prefers false negatives, i.e. pretending that people with a low fever are perfectly normal -- but a lot of private persons I talk to have the opposite preference: they would prefer to think of someone as sick even though they are healthy.
Like any good medical test, you pick a threshold based on what probability you want for false positives and negatives, and you weigh the prior into this judgment. Just investigating what an average resting temperature with a particular measurement method seems to me silly.
- saurik 4y ago> if we use an anal or ear canal thermometer makes temperature vary ±0.4 °C. This part is just known, though: the usual "close enough" standard for core temperature is an anal temperature and everything else you have to adjust. (Everything else you say I agree with, though.)
- kqr 4y agoI know that's common wisdom, but I also have started to doubt it -- when variation is so large, does it really matter whether you measure in the ear or the butt? (For what it's worth, my local hospitals use ear canal temperatures for diagnostic purposes.)
- oefrha 4y agoOf course it does matter, look up systematic error and random error.
- kqr 4y agoBefore being very dismissive, please consider the alternative that I do know about the things you mention, and that there are other ways of looking at the situation. 1. If the ear temperature are consistently wrong (systematic error) it is very easy to debias them and they become equivalent (modulo random error) to anal temperatures. 2. Perhaps cephalic temperature is a better diagnostic tool than gut temperature to evaluate the effects of fever? After all, the brain is a more sensitive organ than the butt.
- sokoloff 4y ago> the brain is a more sensitive organ than the butt The more time I spend on the internet, the less certain of this I become.
- mise_en_place 4y agoAnecdotal, but my family has a history of autoimmune disease (including multiple myeloma in my father’s case). My temp is always slightly higher than what is considered normal. It could be due to how my immune system tends to be overactive, many doctors have claimed it is caused by having “connective tissue disease”. Never had any adverse health problems from it.
- Broken_Hippo 4y agoJust to push back at the anecdote, another anecdote: I personally have an autoimmune disease (MS, in particular, with overactive immune system) and my body temperature has run low for most of my life.
- aleken 4y agoI applaud your accuracy when measuring your kids' temperature. My approach when figuring out if my kids are sick is if their temperature is "high" and their general appearance and conditition is out of the ordinary. The exact decimal of the temperature doesn't matter too much by itself.
- kqr 4y agoWe didn't always care to this accuracy. We just used the anal temperature and went on with our day. Then we got the ear canal thermometer for convenience and discovered that the result was not what we expected, so I got curious and started keeping detailed records... But in the end, I want to get to the point where you are, using a rough rule of thumb. I'm just taking the evidence-based route there!
- kqr 4y agoHah! I just now realised the English word is "rectal" not "anal" but it seems my comment influenced plenty of other people to use the wrong word too!
- fnordpiglet 4y agoOnly an anal person would care. You’re good.
- bombcar 4y agoThe name matters much less than making sure you don’t get the various thermometers confused.
- WelcomeShorty 4y agoI learned that from the move Madagascar :) https://www.youtube.com/watch?v=rQ8m2UqIgrE https://www.youtube.com/watch?v=rQ8m2UqIgrE
- simplotek 4y ago> The exact decimal of the temperature doesn't matter too much by itself. Indeed, this pseudo-accuracy seems pointless. The only relevant conclusions that taking the temperature can deliver is whether, a) there is no fever, b) there is a mild fever not requiring major concern, c) there is a major fever and extra care needs to be taken. No one in their right mind would classify these differences based on sub-degree differences in temperature.
- pmontra 4y agoAnecdotally, after measuring my armpit temperature a number of times in recent years due to checks for covid, I'm close to 36 C or even lower than that. In all my adult life I could deal with anything lower than 38 C without drugs. I would stay warm, rest, sleep on it and be good the next day. I start worrying if it gets past 38.
- IanOzsvald 4y agoWith our infant using a digital thermometer in the ear, we routinely observe that the left ear is hotter than the right. We take 3 measurements in each ear, we see a similar variance as you mention per ear. Have you observed a similar difference? As adults with the same device we don't see a difference in our own ears.
- kqr 4y agoSometimes the ears differ, and we use the warmer of the temperatures as our final measurement, as per the instruction booklet of the thermometer. I have not stopped to consider whether this is a consistent chirality bias or just noise!
- yellow_lead 4y agoMaybe it depends on if your child is left brained or right brained (just kidding)
- bombcar 4y agoI wonder if taking a temperature after laying in your side sleeping would noticeably change based on which ear you were sleeping on.
- m463 4y agoThese kinds of things make me wonder about body asymmetries - like which side the heart is on, and left/right handedness.
- Timshel 4y agoAnyway "Fever Is Your Friend" :). Cf from yesterday : https://www.reddit.com/r/medicine/comments/zwz7t1/dont_worry_parents_fever_is_your_friend/ https://www.reddit.com/r/medicine/comments/zwz7t1/dont_worry...
- e4325f 4y agoI wouldn't have thought a fever is of sufficient concern that it would warrant sticking a thermometer up your childs arse.
- Eisenstein 4y agoWhy? It is easier than getting a toddler to hold it under their tongue and is very accurate.