Fluid Balance: Definition, Formula and How to Calculate

Fluid Balance: Definition, Formula and How to Calculate

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Every human being has different fluid needs. Therefore, it is important to know the figure for fluid requirements and how to calculate fluid balance.

See a more complete discussion about fluid balance below. Check the Urine Color

What is Fluid Balance?

Fluid balance is a balance between the body’s expenditure and intake of fluids, allowing the body’s metabolic functions to work properly. To determine fluid balance, we need to know the body’s fluid requirements and the amount of fluid in and out.

Fluid balance needs to be calculated using the fluid balance statement formula. The goal is to meet our body’s fluid needs in various ways, including consuming fluids with electrolyte content. 

What Are Electrolytes?

Electrolytes are positively and negatively charged substances that can dissolve with bodily fluids. In an adult’s body, around 60% of the body contains water; this means that almost every fluid and cell contains electrolytes. 

Electrolytes play a very important role in the functions of the body’s organs, from brain activity, nerves, and muscle activity, maintaining the balance between fluids inside and outside cells and creating new tissue.

The body will get electrolytes from what we eat and drink. Then, the kidneys filter excess electrolytes from the body into the urine. Apart from that, we can also lose electrolytes when we sweat. 

What is the figure for human body fluid requirements? 

The following is an explanation of the human body’s fluid requirements based on age:

Adult Fluid Needs

According to the Indonesian Ministry of Health, fluid requirements for adults are 2 litres/day or the equivalent of consuming around eight 230 ml glasses of water.

Children’s Fluid Needs

According to IDAI, children’s fluid needs will vary according to age, gender, body fat and muscle mass. The following are fluid requirements for babies, children and teenagers based on age and gender: 

GroupAge RangeDaily Water Intake (ml/day)
Baby0-6 months700 ml
Baby7-12 months800 ml
Children1-3 years1,300 ml
Children4-8 years1,700 ml
Boys9-13 years2,400 ml
Girls9-13 years2,100 ml
Teenage Boys14-18 years3,300 ml
Teenage Girls14-18 years2,300 ml

This table summarizes the recommended daily water intake for different age groups and genders.

Fluid Needs of Pregnant Women

According to the Indonesian Ministry of Health, pregnant women’s fluid needs are at least 2.1 litres or the equivalent of 8 glasses every day. Meanwhile, breastfeeding mothers need 3.1 litres of fluid per day.

Fluid Needs of The Elderly 

Fluid needs for older people are adjusted to gender and age as follows:

GroupAge RangeDaily Water Intake (liters/day)
Elderly Women60-64 years2.3 liters
65-80 years1.6 liters
Over 80 years1.5 liters
Elderly Men60-64 years2.6 liters
65-80 years1.9 liters
Over 80 years1.6 liters

This table outlines the recommended daily water intake for elderly individuals, differentiated by gender and age range.

How to Calculate Fluid Balance 

Fluid balance is calculated using the balance statement formula.

Fluid Balance = Fluid Input – Fluid Output Total

Note:

  • Fluid Input, fluid that enters the body, can be in the form of drinking, eating, or fluid therapy such as infusion and medicines.
  • Fluid Out is fluid measured through urine, vomit and faeces.

How to Calculate IWL (Insensible Water Loss)

IWL is Insensible Water Loss, which is the amount of fluid that comes out of the body that is not realized and is difficult to measure precisely. This fluid loss occurs through evaporation during the respiratory process and evaporation through the skin. The IWL formula is:

Insensible Water Loss (IWL) Formula = Constant Value x Weight (in 24 Hours)

Note: The constant value is 10 – 15, usually depending on each hospital. However, for this example, we will use the constant value 10.

Example of a problem calculating fluid balance

Mrs Anonymous weighs 56 kg, is 45 years old, and is hospitalized in an unconscious condition. This patient had a history of stroke and heart disease in the past two years with blood pressure 90/60 mmHg, respiration 22x/minute, pulse 65x/minute, and temperature 37 ̊c.

When installing an NGT, the patient shows 500 cc of blackish-red gastric fluid, 200 cc of urine, and 100 cc of brownish faeces.

After that, he was given fluid therapy via infusion of 2000 cc/24 hours and a 250 cc PRC blood transfusion, and he was also given antibiotic therapy administered in NaCl at 500 cc/24 hours. 

Here’s how to calculate Mrs Anonymous’s fluid balance:

How to Calculate Fluid Input

  • Infusion = 2000 cc
  • Transfusion = 250 cc
  • Therapy = 500 cc

Calculation: 2000 + 250 + 500 = 2750 cc

How to Calculate Fluid Output

  • NGT = 500 cc
  • Urine = 200 cc
  • BAB = 100 cc

Calculation: 500 + 200 + 100 = 800 cc

How to Calculate IWL

  • Constant Value = 10
  • Body weight = 56 kg

Calculation: 10 x 56 kg = 560 cc

How to Calculate Total Fluid Output

  • Fluid Output = 800 cc
  • IWL = 560 cc

Calculation: 800 + 560 = 1360 cc

How to Calculate Fluid Balance

Based on the calculation results above, the fluid balance value is:

  • Fluid Input = 2750 cc
  • Total Fluid Output = 1360 cc

Fluid balance = Fluid Input – Total Fluid Output 

= 2750 – 1360 

= 1390 cc/24 hours

Fluid balance is a statement of the body’s ability to meet the required fluid intake. By knowing how to calculate body fluid balance, we can determine exactly how much intake the body needs. That way, we can avoid the risky things described above.

What are the consequences if there is a lack of fluids?

Negative balance is a term that can refer to a condition of reduced body fluids where the fluid output is higher than the fluid input.

Besides a lack of fluid entering the body, fluid deficiency can also be caused by higher fluid output figures than fluid input, such as caused by excessive diarrhoea, excessive vomiting, excessive sweating, physical activity, surgery, extensive burns and administration of diuretic drugs. 

So what if the body lacks fluids? The following are the effects of lack of fluids on the body:

  • Decreased Concentration: The mild impact of a lack of fluids can cause a decrease in concentration. It can cause headaches.
  • Heat Attack: Heat attack or heat stroke can also result from a lack of fluids. Lack of fluid will cause joint and muscle cramps, leading to heat stroke because the muscles and heart require fluid intake of 70% of the total daily liquid consumption. 
  • Urinary Tract Infections: Lack of water intake can lead to a buildup of waste products in the kidneys, ultimately leading to a lack of fluids, causing urinary tract infections and kidney stones.

Besides these three things, a lack of fluids can cause various health problems and decreased organ function.

How to Overcome Lack of Fluids?

Dehydration occurs when we don’t have enough fluids in the body. This can happen when the body loses too much fluid due to excessive sweating.

If severe, dehydration can cause serious problems. So, how do you deal with this situation? The following are several things that can prevent and overcome dehydration conditions.

Drink lots of water and foods that contain liquids

Consume lots of fluids, both through water and foods with high water content such as fruits, which can help prevent and treat dehydration.

Consume fluids according to your needs, especially when diarrhoea and sweating, as it requires more extra fluids. 

Consume lots of electrolytes when needed

Sometimes, drinking water alone is not enough to overcome the dehydration you are experiencing. Therefore, more fluids are needed than that, where we can consume drinks containing electrolytes, of course while still paying attention to nutritional needs.

Fluid Infusion

Patients who are treated will usually have an IV installed. This infusion is useful for inserting fluids into the body through a vein. Fluid entering through the veins can affect better fluid balance. Apart from infusions, patients can get fluids through nutritional fluids, intravenous drugs and blood products.

Nowadays, you don’t need to leave the house to get an infusion at a clinic or hospital. Homecare services from Kavacare are ready to provide services infusion at home by professional medical personnel. Get in touch Kavacare Support to get your homecare needs.

Drink more while exercising

When doing strenuous activities or activities that require the body to consume a lot of water, such as exercising with high intensity and for a long time, therefore, drinking lots of water is recommended to maintain your fluid balance.

Determine the color of urine

Another technique you can use to maintain fluid balance is determining the color of urine. The color of urine can indicate how hydrated the body is.

If the urine is light-colored, it means the body is getting enough fluids, while dark urine means the body is dehydrated.

If you experience problems with fluid balance, such as dehydration, you can get a fluid infusion to treat it. Get in touch with Kavacare Support on Whatsapp number 0811 1446 777 to get home infusion services.

 

Source:

  1. Electrolyte. https://my.clevelandclinic.org/health/diagnostics/21790-electrolytes. Accessed August 3, 2022.
  2. Normal amount of water so that there is no shortage of fluids in the body. Accessed August 3, 2022. http://p2ptm.kemkes.go.id/preview/infografhic/berapa-takaran-normal-air-agar-tidak-kekurangan-cairan-dalam-tubuh. Accessed August 3, 2022.
  3. Children’s water needs. https://www.idai.or.id/artikel/seputar-kesehatan-anak/kebutuhan-air-pada-anak. Accessed August 3, 2022. 
  4. Calculate fluid balance. https://www.coursehero.com/file/47708810/Menghitung-Balance-Cairandocx/. Accessed August 3, 2022.
  5. Dehydration. https://www.healthdirect.gov.au/dehydration. Accessed August 3, 2022.
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Reviewed by:
Ditinjau oleh:

Dr. Eddy Wiria, PhD

Co-Founder & CEO Kavacare