What is metabolic acidosis?

Metabolic acidosis is a medical condition where there is too much acid or too little bicarbonate in your blood. It is not a disease in itself, but a sign that something else is affecting the body’s normal balance of these substances.

Around 1 in 10 people with chronic kidney disease (CKD) have metabolic acidosis and this increases to 1 in 4 people on dialysis.

What are the signs and symptoms of metabolic acidosis?

The precise symptoms of metabolic acidosis can vary depending on what has caused the condition and how severe it is.

Symptoms of mild metabolic acidosis can be rather vague and include:

• Feeling and/or being sick
• Loss of appetite
• Feeling generally tired and run down

If the condition gets worse, other symptoms can include:

• Confusion
• Increased heart rate
• Feeling dizzy
• Deeper and/or faster breathing than normal. This happens because your body is trying to get rid of the extra acid by breathing out more carbon dioxide.

If it is not treated, metabolic acidosis can cause long-term health problems including:

• Osteoporosis (a thinning of your bones)
• Muscle weakness
• Delayed growth in children

What causes metabolic acidosis?

Metabolic acidosis occurs when your body produces too much acid.

It can be caused by kidney disease, diabetes, starvation ketoacidosis and severe diarrhoea.

How kidney disease causes metabolic acidosis

Healthy kidneys remove acid from your body in your urine (wee). They also help the body to retain a chemical called bicarbonate which helps control the acid levels in your blood.

If you have kidney disease, this chemical balance is lost which can cause acid to build up in your blood.

• If you have acute kidney injury (AKI) this increase in acid levels is usually temporary and goes down again once your AKI resolves.
• If you have chronic kidney disease (CKD) the effect can be longer lasting.

The more severe your kidney disease is, the higher your risk of developing metabolic acidosis.

How diabetes causes metabolic acidosis

Diabetes can lead to a serious condition called diabetic ketoacidosis when there is not enough insulin. This causes the body to produce acids called ketones, which can make the blood too acidic. In the majority of cases this occurs in type 1 diabetes, but it can occur in type 2 diabetes. Ketoacidosis is often diagnosed by a noticeable fruity smell (like pear drop sweets) on your breath.

How starvation ketoacidosis causes metabolic acidosis

Your body normally uses glucose (sugar) as its energy source. When you do not eat enough, your body switches to burning fat instead. This produces ketones that can lead to starvation ketoacidosis.

How severe diarrhoea causes metabolic acidosis

If your food passes too quickly through your gut, there is not enough time for bicarbonate to be reabsorbed so your blood acid levels can increase.

Diarrhoea can also cause you to become dehydrated which puts extra pressure on your kidneys, making metabolic acidosis more likely to occur.

How is metabolic acidosis diagnosed?

Metabolic acidosis is usually diagnosed by a blood test to check how much bicarbonate is in your blood. This is known as your serum bicarbonate level.

If you are unwell, the pH levels of your blood may also be checked to see how acidic it is.

Urine tests may be needed to find out the exact cause of the metabolic acidosis. They can show how well your kidneys are removing acid and may detect signs of some conditions like diabetes or kidney disease.

How is metabolic acidosis treated?

Treatment for metabolic acidosis can vary depending on the exact cause.

• If you have CKD you may be prescribed sodium bicarbonate tablets to help reduce the acid levels in your blood.
• Bicarbonate is included in the fluids used in dialysis. The amount of bicarbonate may be adjusted if needed.
• Dietary changes may be recommended. Eating more fruits, vegetables and plant-based proteins like beans, peas, lentils and nuts can help to lower the amount of acid in your blood and help you to produce more bicarbonate. You may also be advised to reduce how much meat and dairy you eat as these can increase acid levels.

Always speak to a health professional for personalised advice before you restrict your diet in any way. You will be referred to a kidney dietitian for advice if you need to change what you eat because of your CKD or metabolic acidosis.

Publication date: 07/2026

Review date: 07/2029