July 21, 2020

What is Chloride?

Electrolytes are salts and minerals which conduct electrical impulses in the body. Electrolytes help to move nutrients in and waste products out of cells, as well as maintain the acid-base balance and keeping water levels normal.

Chloride is an electrolyte which is important for maintaining the acid-base balance in the human body. Chloride also works with sodium to keep water levels normal in the body. Chloride levels usually change with sodium levels, but if there’s a change in chloride without sodium this indicates too much acid or base in the body.[1]

Why take a Chloride blood test?

A chloride blood test gives an estimation of the body’s acid-base balance. A major increase or decrease in chloride can signify a serious fluid or electrolyte imbalance which will likely require some treatment to return it to normal.

Dehydration is often a cause of increased levels of chloride, while low blood levels can be a result of prolonged vomiting. Prolonged periods of exercise without adequate hydration can cause an increase in chloride levels, particularly as the body loses both fluid and electrolytes through sweat and urination.

You can test you chloride level within Forth’s Ultimate health check, which includes analysis of 50 key biomarkers integral to health and wellbeing.

What function does Chloride have in the body?

Chloride alongside other electrolytes helps to maintain the acid-base balance in the body and works with sodium to keep water levels within normal parameters.

Most of the chloride in the body is found outside cells and controls water entering and leaving cells. Chloride and sodium work together to regulate blood pressure and blood volume. Increases in chloride can cause a rise in blood pressure and fluid retention which can negatively affect our health.

How do changes in Chloride affect health and wellbeing?

Increased levels of chloride in the blood may indicate dehydration. Dehydration can have a variety of symptoms such as confusion, excessive thirst and headaches which can make you feel unwell. The cause of dehydration may also affect your health and wellbeing negatively. For example, prolonged vomiting increases chloride levels as well as depletes fluid levels in the body.

If you are worried about your chloride level or just want to check where you fall on the range, you can test your level with Forth’s leading blood test service.

What can cause Chloride to change?

When chloride levels increase above normal is known as hyperchloremia. Potential causes of increased chloride levels are:

  • Dehydration
  • Vomiting
  • Diarrhoea
  • Excessive urination
  • Metabolic acidosis
  • Kidney disease

Low levels of chloride are known as hypochloremia and potential causes are:

  • Reduced dietary intake
  • Metabolic alkalosis
  • Medications such as diuretics
  • Addison’s disease

Low chloride levels can occur at the same time as other health conditions such as heart failure and lung disease.

​What are the most common symptoms?

Common symptoms of metabolic alkalosis are:

  • Severe and prolonged vomiting
  • Severe dehydration
  • Increased urine production and output

Common symptoms of dehydration are:

  • Extreme thirst
  • Dark urine
  • Dizziness/light-headedness
  • Headache
  • Tiredness
  • Dry mouth and lips

Although symptoms of metabolic acidosis are not specific, some symptoms are:

  • Chest pain
  • Headaches
  • Palpitations
  • Muscle weakness
  • Nausea
  • Weight gain
  • Altered appetite

How to keep Chloride in the healthy range

Although exercise is an important part of a healthy lifestyle, intense exercise without adequate hydration can lead to fluid and electrolyte loss. When we sweat we lose fluid as well as important ions including chloride. Therefore, you should drink water before, during and after exercise to keep your water levels topped up. If you are participating in the prolonged or intense exercise you may need to consider a sports drink which contains electrolytes or rehydration therapy. If you have experienced vomiting and/or diarrhoea you should use rehydration therapy to normalise your electrolyte levels.

Eating a balanced, healthy diet should help to keep your chloride levels within a normal range. Most chloride is found in table salt or sodium chloride. However, you should be careful not to exceed 6g of salt per day as it can have adverse effects. For example, a diet high in salt raises blood pressure and increases the risk of coronary heart disease. You should always check the labels on food to see how much salt it contains, there are many foods where salt is ‘hidden’. Foods like bread, breakfast cereals and ready meals all have salt added to them in the manufacturing process. Cooking meals from scratch will help you to monitor how much salt you are eating daily.


[1] Lab Tests Online. (2018). Chloride Test. Available at:

View full list of biomarkers

This information has been medically reviewed by Dr Nicky Keay

Nicola has extensive clinical and research experience in the fields of endocrinology and sport and exercise medicine. Nicky is a member of the Royal College of Physicians, Honorary Fellow in the Department of Sport and Exercise Sciences at Durham University and former Research Fellow at St. Thomas' Hospital.

Dr Nicky Keay

Dr Nicky Keay

BA, MA (Cantab), MB, BChir, MRCP.