tangent
12-11-01, 23:35
sroberts
The following may be useful in relation to the discussion on insulin
production:
http://medtech.syrene.net/forum/viewtopic.php?topic=359&forum=18&0
The presence of glucose in urine has long been recognized as an
indication of diabetes, and its detection has been assigned a
high degree of importance by the general public. While its
presence was at one time detected by taste, a more aesthetically
acceptable method (which is also less likely to transmit
infection) is to heat the urine and observe the odor. If the
scent of burning sugar or caramel is detected, there is an
excessive amount of sugar present. A somewhat more precise test
can be conducted using potassium hydroxide or sodium hydroxide in
conjunction with the Dry Benedict reagent (see formulary) formed
from copper sulfate and citric acid. In this test a pea-sized
portion of the Dry Benedict reagent is placed with a test tube
and moistened with three drops of urine. Then a dry pellet of
either of the hydroxides is added and mixed (e.g., by shaking).
Shaking should continue as the mixture boils (as a result of the
exothermic reaction which occurs, not from externally applied
heat). The table shows the test results:
glucose |
concentration | Test Results
(g/L) |
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++
<2 | Solution stays blue/no color change
| or precipitate
|
approx. 2 | Small amount of orange precipitate,
| supernatent liquid stays blue
|
5 | Orange precipitate
|
10 | Orange precipitate which turns brown
|
_>20 | Olive-brown precipitate which rapidly
| turns dark brown
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++
False positives may arise from reducing substances such as
Vitamin C.
Dry Benedict Reagent
The Dry Benedict reagent comprises a powder mixture of copper
sulfate (CuSO4.5H2O) and citric acid in a 1:15 weight ratio.
The reagent is stable, nonhygroscopic, and may be stored
in screw cap containers or snap cap vials.
Preparation (adjust quantities as appropriate):
Mix 20 grams of copper sulfate (CuSO4.5H2O) with 300 grams of
citric acid by grinding using a mortar and pestle. Store the
resulting powder in a dry location.
(The preparation for the reagent may be found in
"Production of Basic Diagnostic Laboratory Reagents, WHO
Regional Publications, Eastern Mediterranean Series; 11,"
WHO, Alexandria, 1995.)
--------
More accurately, the presence of glucose in urine is _the_ definition of
diabetes mellitus.
diabetes = polyuria (increased urine production)
mellitus = sugar
There are other kinds of diabetes, and for all, _the indication_ of its
presence is polyuria.
For D. mellitus, all the other stuff that is done, such as finger sticks
for blood glucose, urine dipstick tests for sugar, and Hgb A 1c levels,
are all different technologies to help aid in the fine control of the
problem. They all have their good uses, but tell you different things.
------
Most people who have had diabetes for very
long know that blood testing tells you what is going on right now. Urine
testing is like reading an old newspaper to find out what has already
happened to you.
---------
Stockpiling supplies is always a good idea.
The urine methods are for when your test strips run out :smile:
There are blood testing methods that could conceivably
be used in a severely austere environment; however, even
the simplest requires materials that are unlikely to be generally
available. For instance, both the Folin-Wu and Folin's improved
micro methods (J. Biol. Chem. 83: 115 et seq., 1930) require tungstic
acid solutions. And, while both can be read approximately (by combining
standard color charts with serial dilution techniques), you are really
better off with a colorimeter. (And finding the color charts is a bear
these
days).
The WHO recommends choosing from one of three enzymatic methods
(hexokinase and glucose-6-phosphate dehydrogenase; glucose oxidase
and peroxidase; or glucose dehydrogenase). These methods require reagents
unlikely to be readily available to those whose entry into the austere
environment
was unplanned, and they can only be used with a working colorimeter or
spectrometer. While they have the advantage of being simple to perform,
and using reagents that are relatively stable, once your supply is
exhausted
you are pretty much stuck.
>
> Yes, the urine tests you decribe are still sold OTC.
No, they aren't - they never were. The urine tests sold OTC
are based on somewhat different chemistry (peroxidase with
a redox indicator).
-------
all these tests check
for different things, they all have a role in the control of D.M. Hbg
A1c will help tell how well you've been controlled over the last couple
of months. Urine testing will help tell you how well you've been
controlled since you last emptied your bladder. Blood (or serum)
testing will tell you how well you are in control *right now*. They are
all important. Don't neglect any of them.
The following may be useful in relation to the discussion on insulin
production:
http://medtech.syrene.net/forum/viewtopic.php?topic=359&forum=18&0
The presence of glucose in urine has long been recognized as an
indication of diabetes, and its detection has been assigned a
high degree of importance by the general public. While its
presence was at one time detected by taste, a more aesthetically
acceptable method (which is also less likely to transmit
infection) is to heat the urine and observe the odor. If the
scent of burning sugar or caramel is detected, there is an
excessive amount of sugar present. A somewhat more precise test
can be conducted using potassium hydroxide or sodium hydroxide in
conjunction with the Dry Benedict reagent (see formulary) formed
from copper sulfate and citric acid. In this test a pea-sized
portion of the Dry Benedict reagent is placed with a test tube
and moistened with three drops of urine. Then a dry pellet of
either of the hydroxides is added and mixed (e.g., by shaking).
Shaking should continue as the mixture boils (as a result of the
exothermic reaction which occurs, not from externally applied
heat). The table shows the test results:
glucose |
concentration | Test Results
(g/L) |
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++
<2 | Solution stays blue/no color change
| or precipitate
|
approx. 2 | Small amount of orange precipitate,
| supernatent liquid stays blue
|
5 | Orange precipitate
|
10 | Orange precipitate which turns brown
|
_>20 | Olive-brown precipitate which rapidly
| turns dark brown
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++
False positives may arise from reducing substances such as
Vitamin C.
Dry Benedict Reagent
The Dry Benedict reagent comprises a powder mixture of copper
sulfate (CuSO4.5H2O) and citric acid in a 1:15 weight ratio.
The reagent is stable, nonhygroscopic, and may be stored
in screw cap containers or snap cap vials.
Preparation (adjust quantities as appropriate):
Mix 20 grams of copper sulfate (CuSO4.5H2O) with 300 grams of
citric acid by grinding using a mortar and pestle. Store the
resulting powder in a dry location.
(The preparation for the reagent may be found in
"Production of Basic Diagnostic Laboratory Reagents, WHO
Regional Publications, Eastern Mediterranean Series; 11,"
WHO, Alexandria, 1995.)
--------
More accurately, the presence of glucose in urine is _the_ definition of
diabetes mellitus.
diabetes = polyuria (increased urine production)
mellitus = sugar
There are other kinds of diabetes, and for all, _the indication_ of its
presence is polyuria.
For D. mellitus, all the other stuff that is done, such as finger sticks
for blood glucose, urine dipstick tests for sugar, and Hgb A 1c levels,
are all different technologies to help aid in the fine control of the
problem. They all have their good uses, but tell you different things.
------
Most people who have had diabetes for very
long know that blood testing tells you what is going on right now. Urine
testing is like reading an old newspaper to find out what has already
happened to you.
---------
Stockpiling supplies is always a good idea.
The urine methods are for when your test strips run out :smile:
There are blood testing methods that could conceivably
be used in a severely austere environment; however, even
the simplest requires materials that are unlikely to be generally
available. For instance, both the Folin-Wu and Folin's improved
micro methods (J. Biol. Chem. 83: 115 et seq., 1930) require tungstic
acid solutions. And, while both can be read approximately (by combining
standard color charts with serial dilution techniques), you are really
better off with a colorimeter. (And finding the color charts is a bear
these
days).
The WHO recommends choosing from one of three enzymatic methods
(hexokinase and glucose-6-phosphate dehydrogenase; glucose oxidase
and peroxidase; or glucose dehydrogenase). These methods require reagents
unlikely to be readily available to those whose entry into the austere
environment
was unplanned, and they can only be used with a working colorimeter or
spectrometer. While they have the advantage of being simple to perform,
and using reagents that are relatively stable, once your supply is
exhausted
you are pretty much stuck.
>
> Yes, the urine tests you decribe are still sold OTC.
No, they aren't - they never were. The urine tests sold OTC
are based on somewhat different chemistry (peroxidase with
a redox indicator).
-------
all these tests check
for different things, they all have a role in the control of D.M. Hbg
A1c will help tell how well you've been controlled over the last couple
of months. Urine testing will help tell you how well you've been
controlled since you last emptied your bladder. Blood (or serum)
testing will tell you how well you are in control *right now*. They are
all important. Don't neglect any of them.