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What is acidosis?

Acidosis means that the amount of acid in the body is greater than normal due to Chronic Kidney Disease or kidney failure.  Normally, acid is produced in the body as a by-products of food metabolism. The kidneys then  remove the acid and  acidity levels are kept under tight control. Too much acid in the body fluids can be due to the kidneys not getting rid of the acid, or the body  producing too much acid. Excess acid production can occur with the consumption of a high animal-based protein diet. Acidosis shows up on a blood test as low bicarbonate level. 

What causes acidosis?

Healthy kidneys keep acid levels in balance by excreting them in the urine. Acidosis is caused by a build-up of these acids in the blood and other body fluids. This usually happens when the kidney function drops below 45%. 

What are the signs and symptoms of acidosis?

Mild acidosis does not usually cause any symptoms and is only detected by blood tests. Moderate to severe forms of acidosis can cause the following symptoms, but these are not specific to acidosis and can be due to other causes:

• Deep and rapid breathing rate, which patients usually describe as shortness of breath.
• Fast heart rate which patients describe as palpitations; particularly on minimal exercise.
• Headache and/or confusion
• Fatigue and lack of energy due to muscle weakness
• Vomiting and/or feeling sick (nausea)
• Loss of appetite
• Bone pains

If you experience any of these symptoms, and you are known to have kidney disease, or high blood pressure or diabetes it is important to let your healthcare provider know immediately. 

What are the complications of acidosis in kidney disease or kidney failure?

• Increased bone loss (osteoporosis): Acidosis can cause the gradual breakdown of bone structure. This predisposes patients to a higher risk of fractures in important bones like hips or spine.
• Progression of kidney disease: Acidosis is one of the known factors in the progression of kidney failure. Untreated acidosis causes excessive scarring in the kidneys, which can eventually lead to kidney failure and the need for  dialysis or transplantation.
• Malnutrition: Albumin is produced by the liver, and is an important protein that helps in the normal function of blood vessels. This prevents  excessive fluid accumulating in the ankle, joints and lungs. Acidosis causes excessive break down of albumin, resulting in low blood levels and is a sign of malnutrition.
• Muscle loss: Acidosis can also cause breakdown of muscle proteins which leads to muscle loss and cause muscle wasting.
• Endocrine disorders: Acidosis interferes with the normal functioning of insulin, which is a hormone produced to control blood sugar levels. This can result in insulin resistance, which can lead to diabetes if left untreated , or not corrected in time. 

How is acidosis treated?

Bicarbonate: Bicarbonate is an alkali (opposite of acid) that is produced in the body to prevent the build-up of acids. However, in patients with kidney disease, acids stay in the bloods instead of being excreted by kidneys in the urine. Low bicarbonate levels in the blood are a sign of acidosis and low bicarbonate levels (less than 24 mmol/l) can also cause the kidney disease to get worse.   A number of studies have shown that treatment with sodium bicarbonate or sodium citrate pills can help prevent kidney disease from deteriorating. Additionally, they also showed an improvement in muscle and bone function as well as improving patient quality of life. Sodium bicarbonate or sodium citrate pills should not be used unless a healthcare provider recommends it. If you experience side effects or are unable to take the prescribed dose of sodium bicarbonate, discuss this with your healthcare provider. 

Diet : Certain types of food items such as red meat or eggs increase the production of acids. On the contrary, vegetables and fruits produce less acids and also have a high alkali content. Kidney dietitians can show you how to safely increase the right type, and amounts of fruits and vegetables in your diet, based on the severity of kidney disease. 

Information in this leaflet has been provided by Professor Magdi Yaqoob, Consultant Nephrologist, Royal London Hospital

Production of this leaflet has been funded by an unrestricted grant from Stanningley Pharma Ltd

Written March 2022

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The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.