Oral rehydration therapy - AbsoluteAstronomy.com

Oral rehydration therapy (ORT) is a simple treatment for dehydration

Dehydration

In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...

associated with diarrhoea, particularly gastroenteritis

Gastroenteritis

Gastroenteritis is marked by severe inflammation of the gastrointestinal tract involving both the stomach and small intestine resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water...

or gastroenteropathy, such as that caused by cholera

Cholera

Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

or rotavirus

Rotavirus

Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...

. ORT consists of a solution

Solution

In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

of salt

Salt

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

s and sugars which is taken by mouth. It is used around the world, but is most important in the developing world

Developing country

A developing country, also known as a less-developed country, is a nation with a low level of material well-being. Since no single definition of the term developing country is recognized internationally, the levels of development may vary widely within so-called developing countries...

, where it saves millions of children a year from death due to diarrhea

Diarrhea

Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

, the second leading cause of death (after pneumonia

Pneumonia

Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...

) in children under five.

History

Prescriptions from the ancient Indian physician Sushruta date back over 2500 years with treatment of acute diarrhea with rice

Rice

Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

water, coconut juice

Coconut water

Coconut water is the clear liquid inside young coconuts . As the fruit matures, the coconut water is gradually replaced by the coconut meat and air. A very young coconut has very little meat; the meat that it has is very tender, almost a gel...

, and carrot

Carrot

The carrot is a root vegetable, usually orange in colour, though purple, red, white, and yellow varieties exist. It has a crisp texture when fresh...

soup. However, this knowledge did not carry over to the Western world, as dehydration was found to be the major cause of death secondary to the 1829 cholera pandemic in Russia and Western Europe. In 1831, William Brooke O'Shaughnessy

William Brooke O'Shaughnessy

William Brooke O'Shaughnessy MD FRS was an Irish physician famous for his work in pharmacology and inventions related to telegraphy...

noted the loss of water and salt in the stool of cholera patients and prescribed intravenous fluid therapy

Intravenous therapy

Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...

(IV) to compensate. The results were remarkable, as patients who were on the brink of death from dehydration recovered. The mortality rate of cholera dropped from 70% to 40% with the use of hypertonic IV solutions. IV fluid replacement became entrenched as the standard of care for moderate/severe dehydration for over a hundred years. ORT replaced it with the support of several independent key advocates that ultimately convinced the medical community of the efficacy of ORT.

In the late 1950s, ORT was prescribed by Dr. Hemendra Nath Chatterjee

Hemendra Nath Chatterjee

Hemendra Nath Chatterjee was a Bengali scientist from West Bengal, India who first formulate and demonstrate the effectiveness of Orally Rehydrated Saline for diarrhea management. His paper regarding this finding was published in Lancet at November 1953. In that paper he states that Avomine can...

in India for cholera patients. Although his findings predate physiological studies, his results failed to gain credibility and recognition because they did not provide scientific control

Scientific control

Scientific control allows for comparisons of concepts. It is a part of the scientific method. Scientific control is often used in discussion of natural experiments. For instance, during drug testing, scientists will try to control two groups to keep them as identical and normal as possible, then...

s and detailed analysis. Credit for discovery that in the presence of glucose, sodium and chloride became absorbable during diarrhea (in cholera patients) is typically ascribed to Dr. Robert A. Phillips. However, early attempts to translate this observation into an effective oral rehydration solution failed, due to
incorrect solution formula and inadequate methodology.

In the early 1960s, biochemist Robert K. Crane

Robert K. Crane

Robert Kellogg Crane is an American biochemist best known for his discovery of sodium-glucose cotransport.-Biography:...

discovered the sodium-glucose cotransport

Co-transport

Co-transport, also known as coupled transport or secondary active transport, refers to the simultaneous or sequential passive transfer of molecules or ions across biological membranes in a fixed ratio...

as the mechanism for intestinal glucose absorption. Around the same time, others showed that the intestinal mucosa was not disrupted in cholera, as previously thought. These findings were confirmed in human experiments, where it was first shown that a glucose-saline oral therapy solution administered in quantities matching measured diarrhea volumes was effective in significantly decreasing the necessity for IV fluids by 80%. These results helped establish the physiological basis for the use of ORT in clinical medicine

Clinical Medicine

Clinical Medicine is a peer-reviewed medical journal published bimonthly by the Royal College of Physicians. It was established in 1966 as the Journal of the Royal College of Physicians of London. It was doubly named between 1998 and 2000, and since 2001 it has appeared as Clinical Medicine. Its...

.

The events surrounding the Bangladesh Liberation War

Bangladesh Liberation War

The Bangladesh Liberation War was an armed conflict pitting East Pakistan and India against West Pakistan. The war resulted in the secession of East Pakistan, which became the independent nation of Bangladesh....

in 1971 convinced the world of the effectiveness of ORT. As medical teams ran out of intravenous fluids to treat the spreading cholera epidemic, Dr. Dilip Mahalanabis

Dilip Mahalanabis

Dilip Mahalanabis is an India biologist. He was the director of International Centre for Diarrhoeal Disease Research, Bangladesh Dilip Mahalanabis (born November 12th, 1934) is an India biologist. He was the director of International Centre for Diarrhoeal Disease Research, Bangladesh Dilip...

instructed his staff to distribute oral rehydration salts (ORS) to the 350,000 people in refugee camps. Over 3,000 patients with cholera were treated, and the death rate

Mortality rate

Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...

was only 3.6%, compared to the typical 30% seen in intravenous fluid therapy. The fact that ORT was delivered primarily by family members instead of trained staff across such a large population in an emergency fashion was demonstrative proof of the utility of ORT against cholera.

Between 1980 and 2006, ORT decreased the number of worldwide deaths from 5 million a year to 3 million a year. Death from diarrhea was the leading cause of infant mortality in the developing world until ORT was introduced. It is now the second leading cause of mortality for children under 5, accounting for 17% of all deaths, second only to pneumonia

Pneumonia

, at 19%. Its remarkable success has led to naming the discovery of its underlying physiological basis as "potentially the most important medical advance [of the 20th] century." ORT is part of UNICEF's GOBI program, a low cost program to increase child survival in developing countries, including growth monitoring, ORT, breastfeeding, and immunization. Despite the success and effectiveness of ORT, its uptake has recently slowed and even reversed in some developing countries. This raises concerns for increased mortality from diarrhea and highlights the need for effective community-level behavioral change and global funding and policy.

The individuals and organizations involved in the development of ORT have been recognized widely. The 2001 Gates Award for Global Health was awarded to the Centre for Health and Population Research, located in Dhaka

Dhaka

Dhaka is the capital of Bangladesh and the principal city of Dhaka Division. Dhaka is a megacity and one of the major cities of South Asia. Located on the banks of the Buriganga River, Dhaka, along with its metropolitan area, had a population of over 15 million in 2010, making it the largest city...

, Bangladesh, for its role in the development of ORT. In 2002, the first Pollin Prize for Pediatric Research

Pollin Prize for Pediatric Research

The Pollin Prize for Pediatric Research is an annual award given to physicians who contribute important advances to the field of pediatrics, and is the only existing international pediatric award. The prize was created in 2002 by Irene and Abe Pollin, and funded by the Linda and Kenneth Pollin...

was awarded to Dr. Norbert Hirschhorn, Dr. Dilip Mahalanabis

Dilip Mahalanabis

, Dr. David Nalin

David Nalin

David R. Nalin is an American physiologist, and Pollin Prize for Pediatric Research and Mahidol Medal winner. Nalin had the key insight that Oral rehydration therapy would work if the volume of solution patients drank matched the volume of their fluid losses, and that this would drastically...

, and Dr. Nathaniel F. Pierce for their contributions in the discovery and implementation of ORT. For promoting the use of ORT, the 2006 Prince Mahidol Award was awarded to Dr. Richard A. Cash

Richard A. Cash

Prof. Richard Alan Cash, MD, MPH is an American global health researcher, public health physician, internist, and Prince Mahidol Medal . He is a and Director of the Program on Ethical Issues in International Health in the of the in Boston...

of Harvard School of Public Health

Harvard School of Public Health

The Harvard School of Public Health is one of the professional graduate schools of Harvard University, located in the Longwood Area of the Boston, Massachusetts neighborhood of Mission Hill, which is next to Harvard Medical School. HSPH is considered a significant school focusing on health in the...

, Dr. David Nalin

David Nalin

, and Dr. Dilip Mahalanabis

Dilip Mahalanabis

in the field of public health; and to Dr. Stanley G Schultz in the field of medicine.

Availability

The World Health Organizations states that some home products can be used to treat and prevent dehydration. This includes salted rice water, salted yogurt drink, and salted vegetable or chicken soup. A home-made solution of one liter of plain water with 3 grams table salt and 18 grams common sugar can also be made. And a medium amount of salt can also be added to water in which cereal has been cooked, unsalted soup, green coconut water, unsweetened weak tea, and unsweetened fruit juice. What should be avoided are commercial soft drinks, commercial sweetened fruit juices, and coffee.

ORT is available anywhere that adequate nutrition is available. ORS, on the other hand, is typically packaged in pre-measured sachets that are ready to be mixed in with water (generally 1L

Litér

- External links :*...

). These are available via commercial manufacturers or supplied by local/regional governments or relief agencies such as UNICEF. In 1996, UNICEF distributed 500 million sachets of ORS to over 60 developing nations. Commercial suppliers produce a variety of formulations, and there is no restriction as to what formulation can be marketed as ORS. As such, some vendors include extra sugar or other flavoring to make the product more palatable, popular examples in the US being the various flavors and formulations of Pedialyte

Pedialyte

Pedialyte is an oral electrolyte solution manufactured by Abbott Laboratories and invented by Gary Cohen, MD of Swampscott, Massachusetts, which is designed to replace fluids and minerals that are lost when a child has diarrhea with or without vomiting...

.

Scheduled to start in October 2011, there is a pilot program in Zambia to piggyback onto Coca-Cola distribution channels using the empty spaces in cases to include Colalife

Colalife

ColaLife is a company limited by Guarantee which aims to leverage the distribution network of The Coca-Cola Company to get simple medicines, such as rehydration salts, and information on how to use them, to the most remote areas in developing countries...

, which are wedge-shaped packets of medicines including oral rehydration salts.

Definition

The definition of ORT has changed over time, broadening in scope and encompassing a definition of a specific therapy appropriate for rehydration. Initially, in the early 1980s, ORT was defined only as the solution prescribed by the WHO

Who

Who may refer to:* Who , an English-language pronoun* who , a Unix command* Who?, one of the Five Ws in journalism- Art and entertainment :* Who? , a 1958 novel by Algis Budrys...

/UNICEF. It was later changed in 1988 to encompass recommended home fluids, because the official preparation was not always readily available. It was amended once again in 1988 to include continued feeding as appropriate management. In 1991, the definition was changed to define ORT as any increase in administered fluids. The final change came in 1993, and is the definition used today, which states that ORT is an increase in administered fluids and continued feeding.

Basic Solution

Where ORS sachets are not available, home-prepared solutions are typically used. While many different recipes exist to increase palatability (e.g. adding flavor, citrus, savory, etc.), all are based on a standard ratio of water, sugar, and salt.

A basic oral rehydration therapy solution is composed of:

30 ml (6 level tsp) of sugar
2.5 ml (1/2 level tsp) of salt, dissolved into
1 litre (4.25 Cups) of clean water

(Note that these expedient rehydration mixtures do not replenish potassium, and usage over long term may result in hypokalemia

Hypokalemia

Hypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low...

WHO/UNICEF definition of ORS

Concentrations of ingredients in reduced osmolarity ORS
Ingredient	g/L Litér - External links :*...	Molecule/ion	mmol Mole (unit) The mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as an amount of a substance that contains as many elementary entities as there are atoms in 12 grams of pure carbon-12 , the isotope of carbon with atomic weight 12. This corresponds to a value... /L Litér - External links :*...
sodium chloride Sodium chloride Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms... (NaCl)	2.6	sodium Sodium Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...	75
glucose Glucose Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate... , anhydrous (C₆H₁₂O₆)	13.5	glucose Glucose Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...	75
potassium chloride Potassium chloride The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state, it is odorless and has a white or colorless vitreous crystal appearance, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are... (KCl)	1.5	potassium Potassium Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...	20
		chloride Chloride The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...	65
trisodium citrate, dihydrate Na₃C₆H₅O₇·2H₂O	2.9	citrate Citrate A citrate can refer either to the conjugate base of citric acid, , or to the esters of citric acid. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate.-Other citric acid ions:...	10

The WHO

Who

Who may refer to:* Who , an English-language pronoun* who , a Unix command* Who?, one of the Five Ws in journalism- Art and entertainment :* Who? , a 1958 novel by Algis Budrys...

and UNICEF jointly maintain the official guidelines for the contents of reduced osmolarity ORS packets. These guidelines are used by manufacturers of commercial ORS packets that are available for purchase and were last updated in 2006. The reduced osmolarity ORS has a total osmolarity of 245 mmol

Mole (unit)

The mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as an amount of a substance that contains as many elementary entities as there are atoms in 12 grams of pure carbon-12 , the isotope of carbon with atomic weight 12. This corresponds to a value...

Litér

- External links :*...

Switch to reduced osmolarity ORS

In 2003, WHO/UNICEF changed the ORS formula to a reduced osmolarity version from what it had been recommending for over two decades prior. This change was in response to numerous studies that showed that the standard ORS formula was ineffective in reducing diarrheal stool output compared to other solutions, including rice water. Additionally, further studies showed that a reduced osmolarity solution not only decreased stool output, but also resulted in less vomiting and fewer unscheduled intraveneous therapy cases. Although UNICEF certifies reduced osmolarity ORS for all forms of dehydration, at least one study cautions that for high stool output cholera-based diarrhea, reduced osmolarity ORS may not sufficiently replenish electrolyte levels, leading to hyponatremia

Hyponatremia

Hyponatremia is an electrolyte disturbance in which the sodium concentration in the serum is lower than normal. In the vast majority of cases, hyponatremia occurs as a result of excess body water diluting the serum sodium and is not due to sodium deficiency. Sodium is the dominant extracellular...

. Though the actual consequence of this appeared negligible, further study was recommended.

The change reduced the osmolarity of the ORS from 311 mmol

Mole (unit)

Litér

- External links :*...

to 245 mmol/L. The ingredients reduced in concentration were glucose

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

and sodium chloride

Sodium chloride

Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

. Potassium

Potassium

Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

and citrate

Citrate

A citrate can refer either to the conjugate base of citric acid, , or to the esters of citric acid. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate.-Other citric acid ions:...

concentrations remained the same. The benefits of the reduced osmolarity ORS are reducing stool volume by about 25%, reducing vomiting by nearly 30%, and reducing the need for unscheduled intraveneous therapy by 33%.

Many Indian pharmacy manufacturers lobbied to oppose this change as the reduction in glucose

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

and sodium chloride

Sodium chloride

concentrations degraded the taste of the ORS solution and hence adversely affected their sales. Dr Dinesh Kumar Tiwari lead a decade long campaign against the old high osmolarity formula, he called "Sweet Killer". The recommendations were at last adopted by CDSCO.

Administration

Current WHO/UNICEF guidelines, recommend that ORT should begin at home with "home fluids" or a home-prepared "sugar and salt" solution at the first sign of diarrhea to prevent dehydration. Feeding should be continued at all times. After initial fluid volume has been restored, the regimen should be switched to official preparations of oral rehydration salts (ORS) at the appropriate dosing times to maintain adequate hydration and proper electrolyte balance.

During the home-prepared stage, care should be taken to select the proper type of fluid to administer. The fluids given must contain both sugar and salt in the proper amounts. Liquids without salt can lead to low body salt (hyponatremia

Hyponatremia

) because the diarrheal stool contains salt that must be replenished. Additionally, sugar must also be present in the administered fluid because salt absorption is coupled with sugar in the intestine via the SGLT1 transporter.

Appropriate drinks to administer during the home-prepared stage include official ORSs, salted rice water

Rice water

Rice water is the suspension of starch obtained by draining boiled rice or by boiling rice until it completely dissolves into the water. This may be used as a weak gruel for invalids...

, salted yogurt-based drinks, and vegetable or chicken soup with salt. Clean water should always be used when preparing a solution. Drinks to be avoided include soft drinks, sweetened fruit drinks, sweetened tea, coffee, and medical tea infusions with diuretic effects due to high sugar content and/or caffeine. In addition, drinks with a high concentration (osmolarity) of sugar can worsen diarrhea as they draw water out of the body and into the intestine because of their hypertonicity.

If dehydration ensues even when ORT is begun with a home-prepared solution, if available, a qualified health professional should manage further rehydration with ORS to ensure proper electrolyte

Electrolyte

In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

balance and to facilitate rapid rehydration, and treatment of the underlying cause of dehydration if appropriate.

Food and supplements

An adult or child with child with diarrhea should continue to eat, and infants should continue to breast-feed. In a 2005 publication for doctors regarding the treatment of diarrhea, the World Health Organization states: "When food is given, sufficient nutrients are usually absorbed to support continued growth and weight gain. Continued feeding also speeds the recovery of normal intestinal function, including the ability to digest and absorb various nutrients. In contrast, children whose food is restricted or diluted lose weight, have diarrhea of longer duration, and recover intestinal function more slowly."

Zinc

Zinc

Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

supplementation is recommended for the management of diarrheal disease in addition to ORS, particularly for pediatric patients. For children under five, zinc supplementation significantly reduces the severity and duration of diarrhea and is strongly recommended as a supplement with ORS for dehydrated children. Preparations are available as a zinc sulfate

Zinc sulfate

Zinc sulfate is the inorganic compound with the formula ZnSO4 as well as any of three hydrates. It was historically known as "white vitriol". It is a colorless solid that is a common source of soluble zinc ions.-Production and reactivity:...

solution for adults, a modified solution for children, and also a tablet form for children.

Treatment when malnourished

The treatment of diarrhea and dehydration in child or adult who is also malnourished is somewhat different from standard treatment. Dehydration may be over-estimated in a marasmic/wasted child and under-estimated in a kwashiorkor/edematous child. The diagnosis is based instead on whether the person has been having diarrhea. The standard reduced-osmolarity oral rehydration solution needs to be modified so that it will have somewhat less salt and somewhat more sugar and potassium than standard in order to produce what is called a Rehydration Solution for Malnutrition (ReSoMal). Or, if diarrhea is severe, the standard reduced-osmolarity solution can be used. In addition, the World Health Organization recommends that all malnourished persons with diarrhea be treated with a course of broad-spectrum antibiotics. Supplemental zinc is still recommended, and a dehydrated person should still continue to be given food.

Physiological basis

Fluid from the body is normally pumped into the intestinal

Intestine

In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...

lumen

Lumen (anatomy)

A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...

during digestion. This fluid is typically isosmotic with blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

because it contains a high concentration of sodium

Sodium

Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

(approx. 142 mEq

Equivalent (chemistry)

The equivalent , sometimes termed the molar equivalent, is a unit of amount of substance used in chemistry and the biological sciences.The equivalent is formally defined as the amount of a substance which will either:...

/L). A healthy individual will secrete 20-30 gram

Gram

The gram is a metric system unit of mass....

s of sodium per day via intestinal secretions. Nearly all of this is reabsorbed by the intestine, helping to maintain constant sodium levels in the body (homeostasis

Homeostasis

Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...

).

Because there is so much sodium secreted by the intestine, without intervention, heavy continuous diarrhea can be a very dangerous and potentially life-threatening condition within hours. This is because liquid secreted into the intestinal lumen during diarrhea passes through the gut so quickly that very little sodium is reabsorbed, leading to very low sodium levels in the body (severe hyponatremia

Hyponatremia

). This is the motivation for sodium and water replenishment via ORT.

Sodium absorption via the intestine occurs in two stages. The first is at the outermost cells (intestinal epithelial cells) at the surface of the intestinal lumen. Sodium passes into these outermost cells by co-transport

Co-transport

via the SGLT1 protein. From there, sodium is pumped out of the cells (basal side) and into the extracellular space by active transport

Active transport

Active transport is the movement of a substance against its concentration gradient . In all cells, this is usually concerned with accumulating high concentrations of molecules that the cell needs, such as ions, glucose, and amino acids. If the process uses chemical energy, such as from adenosine...

via the sodium potassium pump.

The co-transport of sodium into the epithelial cells via the SGLT1 protein requires glucose

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

or galactose

Galactose

Galactose , sometimes abbreviated Gal, is a type of sugar that is less sweet than glucose. It is a C-4 epimer of glucose....

. Two sodium ions and one molecule of glucose/galactose are transported together across the cell membrane

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

through the SGLT1 protein. Without glucose or galactose present, intestinal sodium will not be absorbed. This is the reason glucose is included in ORSs. For each cycle of the transport, hundreds of water molecules move into the epithelial cell, and this brings about the rehydration.

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