ahimsa
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[Edit - When I say "sugar" I mean either glucose, fructose or sucrose (table sugar) ]
I found a web page that talks about oral rehydration therapy -- http://rehydrate.org/ors/ort-how-it-works.htm
I realize that this web page is describing therapy for people (mostly infants and children) who have dehydration due to diarrhea and vomiting (e.g., cholera). But I wonder if any part of the scientific discussion of rehydration therapy also applies to folks who have either dehydration or low blood volume and have some kind of Orthostatic Intolerance? (POTS, NMH/NCS)
Here's the part where it talks about the difference between plain saline vs. when glucose is added:
So, is there anyone out there who understands this science and can tell whether this applies to our patient population? I'd love to know if this is why sometimes (not always!) solutions like pedialyte (or generic versions) seem to help me so much more than just water/salt/potassium, without any sugar.
My other thought is maybe sometimes I just need more potassium. One liter of pedialyte has 20 Meq potassium. My daily prescription of Klor-Con has half of that, 10 Meq.
Here's a much longer extract from the web page for those who want to read more:
I found a web page that talks about oral rehydration therapy -- http://rehydrate.org/ors/ort-how-it-works.htm
I realize that this web page is describing therapy for people (mostly infants and children) who have dehydration due to diarrhea and vomiting (e.g., cholera). But I wonder if any part of the scientific discussion of rehydration therapy also applies to folks who have either dehydration or low blood volume and have some kind of Orthostatic Intolerance? (POTS, NMH/NCS)
Here's the part where it talks about the difference between plain saline vs. when glucose is added:
Simply giving a saline solution (water plus Na+) by mouth has no beneficial effect because the normal mechanism by which Na+ is absorbed by the healthy intestinal wall is impaired in the diarrhoeal state and if the Na+ is not absorbed neither can the water be absorbed. In fact, excess Na+ in the lumen of the intestine causes increased secretion of water and the diarrhoea worsens.
If glucose (also called dextrose) is added to a saline solution a new mechanism comes into play. The glucose molecules are absorbed through the intestinal wall - unaffected by the diarrhoeal disease state - and in conjunction sodium is carried through by a co-transport coupling mechanism. This occurs in a 1:1 ratio, one molecule of glucose co-transporting one sodium ion (Na+).
...
It should be noted that glucose does not co-transport water - rather it is the now increased relative concentration of Na+ across the intestinal wall which pulls water through after it.
So, is there anyone out there who understands this science and can tell whether this applies to our patient population? I'd love to know if this is why sometimes (not always!) solutions like pedialyte (or generic versions) seem to help me so much more than just water/salt/potassium, without any sugar.
My other thought is maybe sometimes I just need more potassium. One liter of pedialyte has 20 Meq potassium. My daily prescription of Klor-Con has half of that, 10 Meq.
Here's a much longer extract from the web page for those who want to read more:
Thanks in advance to any scientist(s) out there who can understand this and can shed some light!In deciding the optimal composition of an oral rehydration solution the following considerations must apply:
- Sodium - losses of sodium in the stool range from 50-60 meg/l to well over 100 meg/l in cholera and in fact total body depletion of sodium may be higher than stool losses alone indicate. For this reason a Na+ concentration of 90 meg/l is considered an optimal figure for replenishing Na+ in dehydration from diarrhoea caused by any etiology and in all age groups from neonates to adults.
For some years there was controversy over optimum concentration of sodium in oral rehydration fluids, which stemmed from the fact that in the early days of its use, particularly in USA, causes of hypernatraemia (excess sodium) occurred fairly frequently in infants given oral rehydration therapy.
The apparently obvious answer was to assume that the sodium concentration in the oral rehydration fluid used was too high and to reduce it (even to as low as 25 or 30 meg/l). Unfortunately, the apparently obvious was not the correct answer - actually nearly all these children were being given high- solute infant formula which tended to make them hypernatraemic to start with and the oral rehydration solution used then contained excess glucose - up to 8% - which was added to provide extra nutritive calories. Unfortunately, the excess glucose caused osmotic diarrhoea which precipitated acute hypernatraemia in these children.
The less obvious but correct answer was to reduce the glucose content - not the sodium. We now recognize that the sodium and glucose should be in a 1:1 ratio in terms of molarity.
Experience has now shown that even hypernatraemic neonates with dehydration can be successfully rehydrated and made normonatraemic using the standard WHO / UNICEF ORS formula (with 90 meg/l Na+) when the water intake is sufficient to ensure normal kidney function and hence physiological regulation of the sodium concentration in the plasma.
Although ORS with a sodium content of around 50 meq/l is sufficient for maintenance of hydration of a normally will-nourished child with diarrhoea it would be inadequate for rehydration of a patient with a secretary diarrhoea (e.g., cholera) losing considerable sodium in the stool.- Glucose should be close to equivalent with the Na+ content - it is 111 mmol/l in the WHO / UNICEF formula, which happens to be exactly 2%. It should be noted that if glucose is present in excess of 3% it will cause further losses of water through osmotic effects, this would also upset the electrolyte balance, since increased water losses will result in hypernatraemia.
- We have not yet given more than a passing mention to potassium. Although as we saw that 98% of the body's potassium is held within the cells, repeated diarrhoeal attacks over a period of time will cause a chronic loss of potassium. This results in muscular weakness, lethargy and anorexia. The typical distended abdomen of a chronically malnourished child is caused by loss of muscle tone in the abdominal wall largely due to chronic depletion of potassium. The kidneys are unable to conserve potassium as they do sodium, and there is a continuous obligatory loss of potassium of about 10 mmol daily in the urine, in addition to the larger losses in the stool.
Potassium is not involved in any way in the sodium/glucose co-transport mechanism and is absorbed passively. Restoration of potassium levels is therefore achieved more slowly than sodium and water restoration. A potassium concentration of 20 mmol/l is considered optimal for the purpose.
Simple mixtures of sugar , salt and water or starch, salt and water contain no potassium and cannot restore potassium depletion - hence these mixtures are an "incomplete" formula and further potassium supplementation is definitely necessary for a child who suffers repeated attacks of diarrhoea.
A potassium-rich diet including, for example, bananas or coconut water can be helpful but an ORS solution containing potassium is therapeutically more effective. In order to produce a significant effect it is necessary to provide potassium-rich foods in reasonable large quantities over a period of time.
Restoring a potassium deficit promotes a feeling of well-being and stimulates the appetite and activity of the child. If additional food is provided over several weeks an increase in weight gain will occur and the status of the child's health will improve markedly. Dietary intake is needed to achieve this.- Electrolyte imbalance and fluid loss also causes metabolic acidosis. These effects are more critical in the case of infants, as their renal function is not fully developed and they have a large surface area in ratio to body weight and a higher metabolic rate. Acidosis is corrected by the addition of bicarbonate (or another base such as citrate) to the ORS formula.