5 Signs of Fluid Overload and Causes of Hypervolemia

Water is known to be important for good health but too much of it can also be dangerous. Although the body is at least 60% water by composition, if too much of fluid accumulates in the system then it can affect health and wellbeing in various ways. This is commonly known as fluid overload. The problem lies with the body being unable to expel the excess fluid rather than it being due to drinking too much of liquids.

What is Hypervolemia?

Hypervolemia is the medical term for fluid overload. It means excess (hyper) volume (vol) in the blood (emia). Fluid overload or hypervolemia specifically refers to excess fluid outside of the cells, meaning that the excess is in the tissue spaces (between cells) and within the bloodstream.

Normally the kidneys control the fluid volume in the body. Excess fluid is passed out with urine. If the fluid content in the body is too low, then fluid is preserved by the kidney when urine is being produced. The kidney maintains this balance of fluid mainly with the effect of the hormone known as ADH (antidiuretic hormone).

To a lesser degree, fluid is also expelled from the body through sweat, stool and with water vapor that is expelled from the lungs. However, there are instances where the fluid loss through these routes can be greater than through urine via the kidneys, in the case of excessive perspiration and profuse diarrhea.

In hypervolemia, the balance between fluid entering the body and fluid being expelled from the body shifts to a point where there is a net accumulation of fluid. Eventually this excess fluid seeps out of the bloodstream and into cavities and tissue spaces. It has a host of effects throughout the body and can ultimately lead to death if severe and left untreated.

Causes of Hypervolemia

Fluid in the body does not exist as pure water. Instead it is part of the blood, cellular fluid and tissue fluid with many different substances in it. These substances, like proteins and electrolytes, can influence the fluid volume. The most notable for fluid balance in the body is the electrolyte known as sodium. Increased sodium is accompanied by increased water and these shifts ensure that water is evenly distributed throughout the body without any excess or deficiency. Therefore the body needs to also regulate sodium levels in order to regulate water levels in the body.

The causes of hypervolemia can be categorized as:

  • Excess water and sodium introduced into the body mainly through intravenous therapy, blood transfusions and to a lesser degree with consumption of large amounts of sodium.
  • Retention of water and sodium as a result of kidney disease, liver disease, heart failure, hormonal disturbances and low protein intake.
  • Shift of fluid into the bloodstream as may occur with administering hypertonic solutions, blood proteins and with treatment for burns.

Read more on causes of fluid retention.

How To Spot Fluid Overload

Mild to moderate fluid overload may not be immediately obvious in the early stages, especially if it is not being monitored by a medical professional. Diagnostic tests may be the only way to verify fluid overload in these instances. Therefore people with one or more of the known causes need to be attentive to the following signs and symptoms.

Swelling of the Arms and Legs

Fluid collects in the tissue spaces and results in swelling. This is most noticeable in the legs where the circulation is not as efficient due to the distance from the heart and the effect of gravity. Swelling may also occur within the arms but to a lesser degree. This is collectively known as peripheral edema. Leg swelling is one of the early symptoms of fluid overload. As the condition worsens then swelling may become evident elsewhere, particularly in the abdomen.

Bloated Abdomen

The excess fluid accumulates in cavities like the abdominal cavity. This bloatingg of the abdomen is known as ascites. Initially the fluid accumulation may not be visible but can be heard with certain movements. Eventually when there is large amounts of fluid the abdomen will appear to be swollen. This visible distension varies but can eventually reach a point where the umbilicus (belly button) becomes everted.

Sudden Weight Gain

A significant portion of the human body weight is due to its water content. Therefore a significant increase in fluid volume will lead to a significant increase in body weight. This happens over a short period of time, within days and sometimes there are small but noticeable changes within hours. The rate of this weight gain does not correlate with obesity-related weight gain due to increased body fat, which is usually slower and gradual.

Coughing and Difficulty Breathing

Shortness of breath is another sign of fluid overload. The heart is strained as it contends with the increased volume and fluid enters the lung which leads to difficulty with breathing. This difficulty breathing is worse when lying flat. Depending on the severity of the pulmonary edema (fluid in the lungs),  a person may report a feeling of suffocation. There  may also be persistent coughing which also may worsen when lying flat.

Lower Urine Output

Although the amount of urine passed out may be within normal limits, it does not correlate with the amount of fluid being consumed or administered. In other words, more water is entering the body than being expelled as urine without there being major fluid loss through sweating, vomiting or diarrhea. In some conditions, the urine output may be abnormally low or even cease altogether for periods of time.


Always consult with a medical practitioner if fluid overload is noticed or suspected. Fluid overload is not immediately life threatening in the early stages, especially if it develops gradually and is not severe. In the event of fluid overload, do not stop drinking water or consuming other fluids unless advised by a medical professional. Also do not attempt to use “water pills” (diuretics) or any other substance to try to rid the body of the excess fluid unless it has been prescibed by a doctor.

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