(2010-08-02)
What is the normal human body temperature?
The usual answer is a simple rule of thumb: 37°C or 98.6°F
(same thing).
This traditional estimate of normal body temperature is originally based on
the findings of
Dr. Carl
Wunderlich (1815-1877)
who recorded about a million armpit temperature measurements on 25 000 patients.
When Gabriel Farhenheit devised his temperature scale in 1714,
he meant
100°F to be the normal temperature of the human body.
However, this turns out to be only a rough estimate which is not
appropriate for clinical thermometry (either the measurement
wasn't accurate or Fahrenheit was running a slight fever at the time).
Modern studies
(1992)
have found the average normal temperature for adults to be close to 98.2°F
(36.8°C).
Older people usually have lower mean body temperatures,
which are normally well below 98.6°F.
The traditional threshold for fever is 38°C (100.4°F).
However, body temperature does depend on the time of day.
For women, it also varies with the phase of the menstrual cycle, which may translate
into a higher baseline body temperature.
It's thus more accurate to base a diagnosis on a curve of the average body
temperature recorded at different times of the day when the person was known to be in good health.
Note that the normal body temperatures
of various warm-blooded animals depends strongly on their species
(it's about 42°C for a healthy chicken).
Normal Body Temperature:
Rethinking the normal human body temperature (Harvard Health Letter)
(2010-08-02)
What is the normal human arterial blood pressure?
During a normal heartbeat, the blood pressure varies between
a minimum (diastolic) and a maximum (systolic).
Both numbers are usually expressed in mmHg (millimeters of mercury)
or torrs (those two units are used interchangeably;
the minute difference
between them makes no clinical difference whatsoever).
In some countries (France, etc.) medical instruments are usually
graduated in centimeters of mercury instead (cmHg).
A typical blood pressure might thus be given as 130/80 in the US and
13/8 in France.
Blood pressure should be measured at the level of the heart itself.
This is one reason why it's usually measured on the upper arm
(the hydrostatic pressure difference between the heart and the lower leg
of a standing person is about 80 mmHg).
Readings can be influenced by many begnign factors,
including posture and recent physical activity.
The normal blood pressure of a healthy person will typically be
between 90/60 and 120/80.
(2010-08-02)
What is the normal pulse rate in humans at rest?
At rest,
a healthy human heart beats at a rate of about 60 pulsations per minute (1 Hz).
The pulse rate of trained athletes can be much lower and the heartbeat of
sedentary people is often faster...
During and after a substantial effort, the pulse of a person quickens.
(2010-08-02)
What dietary caloric intake is considered normal ?
The caloric intake should compensate for the expenditure of energy
spent on basic metabolic functions and physical efforts.
If the intake is more than that, then it is stored the form of body fat.
That fat is burned as needed when more energy is required than what is
provided by the daily intake.
A very rough rule of thumb is that a person burns about 100 W of power
(power is the energy spent per unit of time).
One watt (W) is a joule (J) per second.
A calorie (cal) per second
is 4.184 W.
The unit of energy used by dieticians is the so-called
dietary calorie, large calorie or kilocalorie
whose proper symbol is kcal
(the confusing capitalized symbol "Cal"
was once popular but it's now deprecated).
1 kcal = 1000 cal = 4184 J
If you burn 100 W continuously for a full day
(24 h is 86400 s) you will have burned
8 640 000 J or about 2065 kcal.
Typically a reasonably active average man will consume energy at the above
rate (2000 kcal/day) and should compensate for it
by an equal food intake. The need of other individuals may vary.
For example, a young woman may only need 1200 kcal/day or less.
Dr. Rita Rae Fontenot
(2006-10-19)
Emergency use of an IU rating.
How do I give 125 IU from poorly-labeled 10 mL vials of 10000 units?
This amounts to 1000 IU per mL. 8 doses per mL.
To administer such a small dose (2 drops) with some precision,
you may want to dilute it first.
For example 1 vial in 90 cc
of an inactive solution yields 100 cc,
from which you get 80 doses of 125 IU (1.25 cc each).
If you're a young doctor by herself in a remote area,
I'll just pray that you'll know what to do with whatever means
you have at your disposal
and whatever help you can gather about this emergency.
What is an
IU
worth ?
The IU (International Unit) is a unit of biological activity
which is standardized for each substance
(fairly arbitrarily) by the World Health Organization.
It's also abreviated UI (from the French locution
unité internationale ).
For a simple chemical (e.g., Vitamin C) the WHO simply assigns a value of
1 IU to a particular mass of that substance.
The rating of biological preparations (e.g., vaccines)
is more delicate but it need not be of concern to the practitioner...
If you need to give 125 IU of a substance to a patient,
you must first know the concentration of the solution you have at hand.
Normally, this is shown directly in IU/ml, IU/mL or IU/cc (same thing) on the package.
It could also be given as the reciprocal of that:
For example 1mL/40 IU is the same as 40 IU/mL.
(2007-03-29)
Concentration is amount (grams or moles) per volume.
Blood glucose concentration (bG) is thus given in mg/dL or in mmol/L.
A mole of
glucose
(CAS 50-99-7)
weighs 180.16 grams.
Therefore, a blood glucose concentration
(bG) of 1 mmol/L
is equivalent to 18.016 mg/dL.
The blood glucose concentration given in mg/dL
(the form most commonly used by doctors and
diabetic patients across Europe and the US)
is thus about 18 times the number in mmol/L
(often used in medical research).
Blood
Glucose, Plasma Levels (bG)
| mg/dL | mmol/L |
Interpretation and/or Symptoms |
|---|
| 540 | 30.0 |
Severe imbalance. |
| 360 | 20.0 |
Very high blood sugar level. |
| 270 | 15.0 |
High or very high blood sugar
(depending on patient) |
| 200 | 11.1 |
| 180 | 10.0 |
Non-diabetic postprandial
(i.e., after meal) |
| 144 | 8.0 |
| 108 | 6.0 |
Non-diabetic preprandial
(i.e., before meal) |
| 100 | 5.55 |
| 90 | 5.0 |
| 72 | 4.0 |
Slightly low. Mild lethargy. |
| 54 | 3.0 |
Low blood sugar level. Lethargy. |
| 36 | 2.0 |
Extremely low. Risk of fainting. |
Whole blood concentration is actually 15% lower than the
plasma level quoted above,
but modern portable glucose meters are calibrated to match
the plasma readings obtained in lab tests.
Venous blood and capillary blood may have slighlty different
compositions only when blood chemistry evolves rapidly (after
a meal).
(2007-03-29)
Blood Glucose and HbA1c
Glycated hemoglobin buildup indicates average blood glucose (bG).
The table below gives the rough correspondence between HbA1c results (in %)
and long-term average blood glucose level (bG in mg/dL).
It is based on the following approximative formula:
(mean bG, in mg/dL) = 35.6 (% of A1c hemoglobin)
- 77.3
| HbA1c |
4.0 | 4.1 | 4.2 | 4.3 | 4.4 | 4.5 | 4.6 | 4.7 | 4.8 | 4.9 |
|---|
| Glucose |
65 | 69 | 72 | 76 | 79 | 83 | 86 | 90 | 94 | 97 |
|---|
| |
| HbA1c |
5.0 | 5.1 | 5.2 | 5.3 | 5.4 | 5.5 | 5.6 | 5.7 | 5.8 | 5.9 |
|---|
| Glucose |
101 | 104 | 108 | 111 | 115 | 119 | 122 | 126 | 129 | 133 |
|---|
| |
| HbA1c |
6.0 | 6.1 | 6.2 | 6.3 | 6.4 | 6.5 | 6.6 | 6.7 | 6.8 | 6.9 |
|---|
| Glucose |
136 | 140 | 143 | 147 | 151 | 154 | 158 | 161 | 165 | 168 |
|---|
| |
| HbA1c |
7.0 | 7.1 | 7.2 | 7.3 | 7.4 | 7.5 | 7.6 | 7.7 | 7.8 | 7.9 |
|---|
| Glucose |
172 | 175 | 179 | 183 | 186 | 190 | 193 | 197 | 200 | 204 |
|---|
| |
| HbA1c |
8.0 | 8.1 | 8.2 | 8.3 | 8.4 | 8.5 | 8.6 | 8.7 | 8.8 | 8.9 |
|---|
| Glucose |
208 | 211 | 215 | 218 | 222 | 225 | 229 | 232 | 236 | 240 |
|---|
| |
| HbA1c |
9.0 | 9.1 | 9.2 | 9.3 | 9.4 | 9.5 | 9.6 | 9.7 | 9.8 | 9.9 |
|---|
| Glucose |
243 | 247 | 250 | 254 | 257 | 261 | 264 | 268 | 272 | 275 |
|---|
| |
| HbA1c |
10.0 | 10.1 | 10.2 | 10.3 | 10.4 | 10.5 | 10.6 | 10.7 | 10.8 | 10.9 |
|---|
| Glucose |
279 | 282 | 286 | 289 | 293 | 297 | 300 | 304 | 307 | 311 |
|---|
| |
| HbA1c |
11.0 | 11.1 | 11.2 | 11.3 | 11.4 | 11.5 | 11.6 | 11.7 | 11.8 | 11.9 |
|---|
| Glucose |
314 | 318 | 321 | 325 | 329 | 332 | 336 | 339 | 343 | 346 |
|---|
| |
| HbA1c |
12.0 | 12.1 | 12.2 | 12.3 | 12.4 | 12.5 | 12.6 | 12.7 | 12.8 | 12.9 |
|---|
| Glucose |
350 | 353 | 357 | 361 | 364 | 368 | 371 | 375 | 378 | 382 |
|---|
| |
| HbA1c |
13.0 | 13.1 | 13.2 | 13.3 | 13.4 | 13.5 | 13.6 | 13.7 | 13.8 | 13.9 |
|---|
| Glucose |
386 | 389 | 393 | 396 | 400 | 403 | 407 | 410 | 414 | 418 |
|---|
| |
| HbA1c |
14.0 | 14.1 | 14.2 | 14.3 | 14.4 | 14.5 | 14.6 | 14.7 | 14.8 | 14.9 |
|---|
| Glucose |
421 | 425 | 428 | 432 | 435 | 439 | 442 | 446 | 450 | 453 |
|---|
