Different reading from digital and glass mercury rectal thermometer.

I came down with a cold this week, and I took a rectal temperature with my glass rectal thermometer. The reading was 100.2. I decided to compare that reading with my digital thermometer. It registered 99.4 rectally. It always seems to register almost one degree lower then the glass thermometer. Have any members noticed this difference when taking a temperature. I feel my mercury thermometer is the most accurate of the two.

What are the accuracy tolerances of the two thermometers? I would not be surprised if either is something like +/- 0.5 degrees. If that were the case, your two readings are essentially the same. And what difference does it make? Not trying to be difficult, but what would you do differently between the two readings? Both would indicate you have a low grade fever IF normal for you is lower than those numbers.

Now, if you were a cat, both readings would be low.

Absolutely correct Quincy. Having precise readings for any illness is unnecessary. It's more the trend.

The previous posters are right. If you like having a glass rod in your butt, go for it. It's not that critical until you get into the 104-105 range.

Nimmy, Agree fully. But before you put too much faith in any home thermometer, you need to understand how accurate it is. There is some degree of error in all readings. For example, home ovens are often off by as much as 20 degrees.

Like most are saying, I've noticed personally, and there always will be, some give on readings between thermometers.

Medical research hasn't determined an exact correlation between oral, rectal, ear, armpit, and forehead temperature measurements. Generally, the correlation of temperature results are as follows:

- The average normal oral temperature is around 98.6°F (37°C). However it can range from 97F (36.1C) to 99F (37.2C).

- A rectal temperature is 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature.

- An ear (tympanic) temperature is 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature.

- An armpit (axillary) temperature is usually 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature.

- A forehead (temporal) scanner is usually 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature.

With regards to the accuracy various study have shown that the temperatures can vary from 0.05C (0.09 F) to 1C (1.8F) lower between digital and traditional mercury glass thermometers.

As previously stated real accuracy is only required when patients develops a high grade pyrexia (fever ) in the range of 103F ( 39.4C) to 104 F (40C) and very critical when a patient becomes hyperpyrexial 106.7F (41.5C) due to the risk of brain damage and death .

Thanks RN1993 for your very informative answer to the question posed here.

They all seem to be pretty much the same but I can tel you from recent experience that the type of temp taken depends on the hosp/doc/and dept Because I suffer from allot of medical problems and I see allot of different specialists and end up in allot of ER s all are basically the same and left up to the dept heads etc. I was at one hospital waking from a seizure when a very nice nurse was informing me that it was policy to take rectal temps on patients like me etc. etc.etc... I was still kinda out of it and more concerned about having a seizure in my favorite Chinese restaurant in the middle of lunch and the 900000 needles sticking out of me! But from what I have seen in all of the doc offices I have been in as well as Hospitals and plenty of other assorted medical settings (real not fantasy too bad) it is basically up to the budget and preference of the particular people in charge. BTW I get Alot of injections for various ailments and although at first I was told that contrary to my belief IM did not mean that I could recieve injections in my glutes after a few painful shots in my arms i had another nurse say no prob with my bottom it is my body after all. Only catch one in each side I had no prob with this. When the regular nurse came back I ended up with 50/50 (one in arm one in bottom) she left now I get them all in my bottom hurts much less but now you should see some of the surprised looks that I get from nurses IOI some understand and I tell the ones who do not don't knock it till you try it! little off this topic but just MHO Have a great one -Phil

As a female friend and a registered nurse talking with me on this subject had a quaint phrase regarding temperature taking. "You don't want to pass getting glass in the ass when you're temp is being taken. Best way, best thermometer"

Yes, and this I've heard from a number of medical people; that the "gold standard of determining a body temperature is by use of a glass mercury rectal thermometer in the rectum for a minimum of three minutes. A well maintained glass mercury thermometer is very reliable as opposed to digital and probe types, both dependent on battery as the power source.

After reading about the Kinsa thermometer here, I bought one. The first time I tried it out, I used a probe cover and lube and got a reading of 98.1. That seemed a little low, so I took my temperature with it three more times and got 97.5, 97.3 and97.7. Then I took my temperature with a glass and Mercury basal thermometer and got 98.5. I tried the Kinsa again twice more without a probe cover or lube and got 98.1 and 98.2. This morning I checked the basal thermometer against the FILAC and got 98.5 with the basal and 98.3 with the electronic. Then I tried the Kinsa again with a probe cover and got 98.1 and 98.2. I was careful this time to only insert the probe as far as the end of the silver tip. It seems positioning is important with the Kinsa, although both the Kinsa and the FILAC seem to read slightly lower than the glass and mercury basal thermometer. If you're going to use a Kinsa rectally, it's probably better to have someone else take your temperature (isn't it always?) so that they can see to position the probe just right. We always use the glass for play purposes, but occasionally the electronic if we're really sick, depending on how we're feeling and if we want the most accurate temperature or just a quick check. After this, though, maybe we'll stick to the glass all the time.

If the glass thermometer is one of reputable quality.....such as B-D, Atlas, etc......then I'd say it's definitely the most accurate of the two. Even higher end digital thermometers like we use at the hospital are sometimes off by at least one or two tenths of a degree. There's just no tricking or screwing up the system of plain mercury moving through a balanced glass tube.

A tympanic "thermometer" isn't a thermometer! It computes a temperature based on the emitted infrared radiation from the ear drum. The reported "temperature" is a best guess of the computer in the "thermometer" which assumes a clear ear canal and normal anatomy, on a patient who is indoors, at room temperature.

One example, on an afternoon with a bad case of boredom I took my temperature with an ear thermometer 30 times. Bear in mind I did NOT have a fever. The readings ranged from 97.3 to 102.9 ! The unit was not broken, it's just the nature of the beast.

Another example was a nurse in the pediatric clinic commenting that she couldn't understand how her patient could have a normal temperature in his LEFT ear, and a fever in his RIGHT ear! Infected right ear, blood vessels dilated means more radiation means a higher reading!

I once saw a nurse in a PACU use an ear thermometer to take axillary temperatures on post op patients.. Point, click, it displayed a number, so she charted it! Don't know what she was measuring, but it wasn't a temperature.

Electronic thermometers generally don't have an absolute temperature reference, the indicated temperature is a conversion from a voltage or resistance from an element who's characteristics change with temperature. They're going to vary a little depending on conditions.

Nurse Nikki is absolutely right.. Mercury in glass is hard to trick or mess up. (Just remember they're fragile, and it's all good)

Just my $0.02

Doc

Technology took over, and left us with the digital thermometer. For those of us with an rt fetish, it's a major disappointment. The vintage glass, coated in Vaseline, was the ultimate rectal temp. experience. One you've tried it, there's no turning back. It's becoming rare these days to even find a vintage rectal thermometer with a classic design, and if you do, it will cost you. Someone should re-manufacture them, and I don't doubt that there would be a market for it.

Nothing can replace a glass rectal thermometer