Total Body Water Calculation

Water is an important component to initiate any function in the human body. Total body water evaluation is required to correct various fluid electrolyte abnormalities. Moreover, total body water plays the main role to diagnose various renal disorders. In addition, our body enzymes use a watery medium to enhance our activities. The total body water calculation provides a complete evaluation of the volume of water in the body. 

There are two types of total body water calculators based on a person’s age. One type is for pediatric purposes. Moreover, the other total body water calculator type is for adults’ use. Both these types provide the accurate value of total body water to know the status of homeostasis.

The body loses water content in breathing, sweating, digestion, and several other activities. It is important to rehydrate the body to fulfill the body’s requirements. The total body water calculation also provides a complete evaluation to assess the water volume in the body. Water volume in the body is necessary to differentiate 32 between a fatty solid mass and a fat-free mass.

What is total body water?

Total Body Water is the total water content present in the tissues, blood, plasma, and anywhere else in the body. Our body mainly consists of water to maintain a proper weight.

Water is present in two main body divisions. Intracellular fluid (ICF), water present inside the cells, covers almost two-thirds of total body water. Extracellular fluid (ECF), water present outside the cellular compartment, completes the remaining one-third of total body water.

The percentages of body water, intracellular and extracellular, add up to conclude total body water. It is necessary to ensure constant water values and within the normal range to ensure effective homeostasis.

Why is water important for the normal functioning of the human body?

Our body enzymes require a water medium to perform their functions. Most of the body’s functions are catalyzed by enzymes. And enzymes require an aqueous medium. Moreover, there are also several other roles of water in different parts of the human body. These roles ensure the importance of water for normal body functioning. Some of the main reasons are as follows to understand the role of water in the human body.

• Protects joints, joints, and spinal cord by proper lubrication
• Water helps in the excretion of toxins and waste products through kidneys.
• The digestion process initiates with saliva. The major component of saliva is water.
• Water ensures body hydration and reduces the risk of dehydration.
• Water is necessary for the enzymes to start their function. Nothing is possible without enzymes in our body.
• Water plays a key role in the metabolism of carbohydrates and proteins.
• Water maintains osmoregulation and thermoregulation to balance homeostasis.
• Water is also a part of amniotic fluid. Amniotic fluid is a shock absorber for the embryo in pregnancy to protect from any trauma.

Why is there a need to calculate total body water?

Total body water exhibits fluctuations by different renal diseases and medications. Moreover, total body water tells about a lot of ongoing pathologic processes in the human body. Information related to the total body water is helpful to determine body mass composition and its divisions. Detailed knowledge of a patient’s total body water can help to diagnose and treat fluid and electrolyte imbalance. 

The total body water of the human body is in the form of extracellular and intracellular fluid. Any change in the defined percentages of these fluids may cause a drastic change in the human body.

For example, extracellular fluid contributes approximately 25% of the total body water. A 40% rise in extracellular water would result in only a 10% increase in total body water, which is not usually detected. These changes are of prime clinical importance. Extra fluid retention in the extracellular compartments may cause an increased morbidity rate in severely ill patients.

Therefore, It is necessary to calculate total body water content for acutely ill patients. Total body water shows fluctuation in different conditions. Some of them are as follows.

• Changes in fluid values after various drug intake. For example diuretics

• Drug distribution in individuals with lowered total body water volume
• Changes in body composition under different physical conditions, such as dehydration, disease, or exercise

What are the formulas to determine total body water?

There are different total body water calculation formulas to evaluate the total volume of water in the body. These total body water calculation formulas depend on age, weight, height, and gender. Moreover, these formulas are different for males and females. Let us have a look at these formulas to evaluate total body water.

Watson Formulas

Male total body water = 2.447 – (0.09156 x age) + (0.1074 x height) + (0.3362 x weight)
Female total body water = -2.097 + (0.1069 x height) + (0.2466 x weight)

Hume-Weyers Formulas

Male total body water = (0.194786 x height) + (0.296785 x weight) – 14.012934
Female total body water = (0.34454 x height) + (0.183809 x weight) – 35.270121

Mellits-Cheek Formulas

This total body water calculator formula is specifically designed for children. There are different values of total body water in adults and children. Therefore, there is a separate formula for the children to determine total body water.

Male total body water (height lesser than 132.7 cm) = -1.927 + 0.465 x weight + 0.045 x height
Male total body water (height greater than 132.7 cm) = -21.993 + 0.406 x weight + 0.209 x height

Female total body water (height lesser than 110.8 cm) = 0.076 + 0.507 x weight + 0.013 x height
Female total body water (height greater than 110.8 cm) = -10.313 + 0.252 x weight + 0.154 x height

How to use a total body water calculator?

It is simple to use a total body water calculator. You only need to put values in the above-mentioned total body water calculation formulas. Mention your height in centimeters. Put your age, current weight, and gender to find out your total body water volume. Click the calculate button after putting values. In this way, the total body water calculator will provide you with the results according to your given values.

What are the total body water variations in infants?

An infant’s body weight consists of the first year of age. Water content continues to decrease with increasing age. The main reason for the lower water content is that children gain more body fat and less fat-free mass with passing growth period.

The water ratio for infants is as follows:

• From birth- 6 months: Average total body water = 74% (ranges from 64% – 84%)
• 6 – 12 months: Average total body water = 60% (ranges from 57% – 64%)
• 12 months – 12 years: Average total body water = 60% (ranges from 49%– 75%)

What are the normal reference values of the total body water for adults and older persons?

The normal values of total body water vary according to the age of the person. Let us have a look at the normal values of total body water for a better understanding.

• For males:
• 12-18 years of age:

Average value = 59%, normally ranges from 52-66%

• 19-50 years of age:

Average value =59%, normal range is 43-73%

• Greater than 51 years of age:

Average value = 56%, normally ranges from 47-67%

• For females:
• 12-18 years of age:

Average value =56%, normally ranges from 49-63%

• 19-50 years of age:

Average value =50%, normal range is 41-60%

• Greater than 51 years of age:

Average value = 47%, normally ranges from 39-57%

Conclusion

Are you curious about your own total body water volume in the body? This total body water calculation helps you to evaluate the total body water volume. Total body water calculation help to determine the total water volume in the body. These total body water calculations depend on age, height, current weight, and gender to provide accurate results.  Any alteration in the values of water content from the normal range may lead to several changes in the body functions.

There are different types of formulas for children and adults. Females possess a bit lower water content than males. Therefore, these total body water calculations depend on gender. You only need to put values in the formula in the preferred parameter. Press the calculate button. It will provide you with accurate results of the total body water.

Frequently asked questions (FAQs)