Difference Between Hydration and Hydrolysis

Hydration and hydrolysis are two common terms encountered in the clinical medicine and biochemistry respectively. Although they sound the same and are both related to water as the term “hydro” suggests, the processes are very different.


Hydration is the medical term for water intake. This may be drinking or intra-venous fluid input. Hydration is extremely important because all the biological reactions occur in a water medium. When the amount of water in the body is low due to any reason it is called dehydration. Body water loss may occur due to water loss as vapor, urine and diarrheal fluid. Dry mouth, lack of tears, lack of salivation, sunken eyes, reduced skin elasticity, low urine output, low blood pressure and a compensatory rise in heart rate are common features of dehydration. Out of the aforementioned symptoms and signs, the first few are the first to appear; these suggest mild dehydration. Low skin turgor and low urine output suggest moderate fluid loss. Low blood pressure and high heart rate suggest severe dehydration. Features of dehydration in babies may be more subtle. Listlessness, lethargy, excessive crying, sunken eyes, sunken fontanelle may occur, in addition to other features.

According to the degree of severity of dehydration, oral fluid replacement or intra-venous fluid therapy may be used to correct the water deficit. Drinking water is adequate to replenish the lost water in mild to moderate dehydration. Severe dehydration associated with complications should be treated with intravenous fluids like 0.9% sodium chloride, Hartmann solution and Ringer’s Lactate solution. Oral rehydration salts are especially useful in treating electrolyte loss in watery diarrhea. There is a hyper-hydration as well, which lies at the other end of the spectrum. Excessive fluid intake, especially intravenous intake, may lead to the collection of fluid in lungs, peritoneum and dependent areas. Collection of fluid in lungs is called pulmonary edema. Collection of fluid in the peritoneum is called ascites. This situation needs water loss to bring the water balance back to normal. Diuretics may be used to flush the water out of the body through the kidneys, as urine. Electrolyte levels should be monitored during diuretic therapy.


Hydrolysis is a chemical reaction where a water molecule is spilt, and the resultant ions are used to cleave a covalent bond. This is a reaction which occur is the body very commonly. Hydrolysis is a reaction which helps mobilize the body’s energy stores, to breakdown proteins, lipids and carbohydrates. Hydrolysis is one of the reasons for biological reaction occurring in a water medium. Water consists of two hydrogen atoms and one oxygen atom. The bonds between these are very strong, and a lot of energy is needed to split the water molecule into hydrogen cation and a hydroxide anion. This high energy need is circumvented by the presence of enzymes in the body. Glycogen breakdown is a good example for a hydrolytic reaction aided by an enzyme. Hydrolysis of bonds between hexose sugars in glycogen releases sugar into the blood stream.

What is the difference between Hydration and Hydrolysis?

• Hydration is water intake while hydrolysis is the breakdown of complex bonds by splitting a water molecule.