biology

Oral rehydration therapy

Oral rehydration therapy is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Oral rehydration therapy rather than just read about it. In short: Oral rehydration therapy (ORT) is a type of fluid replacement used to prevent and treat dehydration, especially due to diarrhea. It involves drinking water with modest amounts of sugar and salts, specifically sodium and potassium.

Key takeaways

Oral rehydration therapy belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Oral rehydration therapy to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Oral rehydration therapy from memory before moving on to harder problems.

Reference excerpt

Oral rehydration therapy (ORT) is a type of fluid replacement used to prevent and treat dehydration, especially due to diarrhea. It involves drinking water with modest amounts of sugar and salts, specifically sodium and potassium. Oral rehydration therapy can also be given by a nasogastric tube. Therapy can include the use of zinc supplements to reduce the duration of diarrhea in infants and children under the age of 5. Use of oral rehydration therapy has been estimated to decrease the risk of death from diarrhea by up to 93%. Side effects may include vomiting, high blood sodium, or high blood potassium. If vomiting occurs, it is recommended that use be paused for 10 minutes and then gradually restarted. The recommended formulation includes sodium chloride, sodium citrate, potassium chloride, and glucose. Glucose may be replaced by sucrose and sodium citrate may be replaced by sodium bicarbonate, if not available, although the resulting mixture is not shelf stable in high-humidity environments. It works as glucose increases the uptake of sodium and thus water by the intestines, and the potassium chloride and sodium citrate help prevent hypokalemia and acidosis, respectively, which are both common side effects of diarrhea. A number of other formulations are also available including versions that can be made at home. However, the use of homemade solutions has not been well studied. Oral rehydration therapy was developed in the 1940s using electrolyte solutions with or without glucose on an empirical basis chiefly for mild or convalescent patients, but did not come into common use for rehydration and maintenance therapy until after the discovery that glucose promoted sodium and water absorption during cholera in the 1960s. It is on the World Health Organization's List of Essential Medicines. Globally, as of 2015, oral rehydration therapy is used by 41% of children with diarrhea. This use has played an important role in reducing the number of deaths in children under the age of five.

Medical uses

ORT is less invasive than the other strategies for fluid replacement, specifically intravenous (IV) fluid replacement. Mild to moderate dehydration in children seen in an emergency department is best treated with ORT. Persons taking ORT should eat within six hours and return to their full diet within 24–48 hours. Oral rehydration therapy may also be used as a treatment for the symptoms of dehydration and rehydration in burns in resource-limited settings.

Efficacy

ORT may lower the mortality rate of diarrhea by as much as 93%. Case studies in four developing countries also have demonstrated an association between increased use of ORS and reduction in mortality. ORT using the original ORS formula has no effect on the duration of the diarrheic episode or the volume of fluid loss, although reduced osmolarity solutions have been shown to reduce stool volume.

Treatment algorithm The degree of dehydration should be assessed before initiating ORT. ORT is suitable for people who are not dehydrated and those who show signs and symptoms of mild to moderate dehydration. People who have severe dehydration should seek professional medical help immediately and receive intravenous rehydration as soon as possible to rapidly replenish fluid volume in the body.

Contraindications ORT should be discontinued and fluids replaced intravenously when vomiting is protracted despite proper administration of ORT; or signs of dehydration worsen despite giving ORT; or the person is unable to drink due to a decreased level of consciousness; or there is evidence of intestinal blockage or ileus. ORT might also be contraindicated in people who are in hemodynamic shock due to impaired airway protective reflexes. Short-term vomiting is not a contraindication to receiving oral rehydration therapy. In persons who are vomiting, drinking oral rehydration solution at a slow and continuous pace will help resolve vomiting.

Preparation

WHO and UNICEF have jointly developed official guidelines for the manufacture of oral rehydration solution and the oral rehydration salts used to make it (both often abbreviated ORS). They also describe other acceptable solutions, depending on material availability. Commercial preparations are available as prepared fluids and as packets of powder ready to mix with water. A basic oral rehydration therapy solution can also be prepared when packets of oral rehydration salts are not available. The molar ratio of sugar to salt should be 1:1 and the solution should not be hyperosmolar. The Rehydration Project states, "Making the mixture a little diluted (with more than 1 litre of clean water) is not harmful." The optimal fluid for preparing oral rehydration solution is clean water. However, if this is not available, the usually available water should be used. Oral rehydration solution should not be withheld simply because the available water is potentially unsafe; rehydration takes precedence. When oral rehydration salts packets and suitable teaspoons for measuring sugar and salt are not available, the WHO has recommended that homemade gruels, soups, etc., may be considered to help maintain hydration. A Lancet review in 2013 emphasized the need for more research on appropriate home made fluids to prevent dehydration. Sports drinks are not optimal oral rehydration solutions, but they can be used if optimal choices are not available. They should not be withheld for lack of better options; again, rehydration takes precedence. But they are not replacements for oral rehydration solutions in nonemergency situations.

Reduced-osmolarity

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Oral rehydration therapy

Start with the simplest possible case. Write down what Oral rehydration therapy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Oral rehydration therapy before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Oral rehydration therapy ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Oral rehydration therapy

In research: Oral rehydration therapy appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Oral rehydration therapy in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Oral rehydration therapy is common in secondary-school and first-year university syllabi. It links to neighbouring topics Body water, Cholera, Dehydration, so understanding it makes those chapters shorter.
In everyday life: Look for Oral rehydration therapy outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Oral rehydration therapy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Oral rehydration therapy means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Oral rehydration therapy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Oral rehydration therapy in simple terms?

Why does Oral rehydration therapy matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Oral rehydration therapy?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Oral rehydration therapy.