Metabolic Acidosis

Metabolic acidosis is too much acid in the blood. It is more common in people with advanced CKD and can be life-threatening if not treated appropriately.

Metabolic acidosis means there is too much acid in your blood. This can happen when your body makes too much acid, cannot remove enough acid from the blood, or both. People living with chronic kidney disease (CKD) are at risk for metabolic acidosis, especially in more advanced stages of CKD when the kidneys have more trouble removing acid from the blood.

Not everyone will have symptoms, or the symptoms may be hard to notice. These can include:

• Changes in breathing
  • At first, breaths are usually fast and deep (often described as “air hunger”)
  • As acidosis worsens, breathing becomes slower, deeper, and harder
• Fast heartbeat
• Confusion
• Feeling very tired and/or weak
• Nausea
• Vomiting
• Loss of appetite

There are usually no symptoms in milder cases or if the acidosis develops slowly.

Other symptoms may also be present depending on the underlying disease or condition that is causing the metabolic acidosis, like kidney failure, heart failure, or severe asthma.

Kidney disease is one of the most common causes of metabolic acidosis. This includes CKD and acute kidney injury (AKI). Healthy kidneys remove natural waste products from your blood, including acids. Kidney disease can cause metabolic acidosis when your kidneys are not able to remove enough acid from your blood, causing a build-up in your body.

Risk factors for metabolic acidosis for people living with CKD include:

• Lower estimated glomerular filtration rate (eGFR) – as your eGFR goes down, your risk goes up
• Hyperkalemia (high potassium levels)
• Albuminuria
• Smoking
• Anemia (low red blood cell level)

Other causes of metabolic acidosis that are not directly related to kidney disease include:

• Diabetes-related ketoacidosis (DKA) – when your body doesn’t have enough insulin available, your sugar levels go very high and create ketones (a form of acid). This is more likely in people living with type 1 diabetes.
• Lactic acidosis – can be caused by other conditions like cancer, drinking too much alcohol, liver failure, heart failure, severe anemia, seizures, sepsis, and/or severe asthma
• Severe diarrhea
• Severe dehydration
• Aspirin overdose
• Poisoning by ethylene glycol (antifreeze) or methanol

Without treatment, metabolic acidosis can cause many long-term health problems. These include:

• Thinning of your bones (osteoporosis) – the higher acid levels can cause your bones to wear down faster and makes them weaker. This raises your chance of bone fractures in your most important bones like your hips and spine. The risk is increased even more if you also have mineral and bone disorder (also a complication of CKD).
• Muscle weakness and/or loss (sometimes referred to as “muscle wasting”) – just like your bones, the higher acid level can wear down your muscles. This can lower your strength and exercise abilities.
• Worsening of CKD - exactly how this happens is not clear. The acid build-up makes your kidney function go down; and as your kidney function goes down, the acid level builds up more. Without proper treatment, this cycle continues and can speed up the CKD disease process.
• Decreased growth in children - metabolic acidosis can prevent the release of growth hormone, which is needed for proper growth.
• Death - studies have shown a link between metabolic acidosis and an increased risk for death.

Tests

Metabolic acidosis is often diagnosed with a simple blood test. This test looks for how much bicarbonate is in your blood – also known as a “serum bicarbonate” level. This test is often ordered as part of a larger group of tests, known as a “basic metabolic panel (BMP)” or “comprehensive metabolic panel (CMP)”.

Bicarbonate is not an acid, it’s actually the opposite (also known as a “base”). Your body needs bicarbonate in the blood to stop it from getting too acidic. Most of the bicarbonate in your body is in the form of carbon dioxide (CO2), a waste product from your body turning food into energy. So, another name for this blood test is your “serum carbon dioxide (CO2)” level.

Instead of measuring for high levels of acid, it’s easier to measure for low levels of base.

Your healthcare professional may also request a urinalysis to check the acidity of your urine (pee). In more severe cases, your healthcare professional may draw a small amount of blood from an artery in your wrist, arm, or groin to check the acidity. This is also known as an arterial blood gas (ABG) test.

Overview

Treatment for metabolic acidosis is mostly focused on nutrition (the types of foods that you eat). If this is not enough to lower your body’s acid levels, medication can be considered.

Nutrition

The main approach to treating metabolic acidosis is through your diet. Increasing the amount of fruits, vegetables, and plant-based proteins you eat each day helps lower the amount of acid in your body. This is because fruits and vegetables produce alkali (also known as base, the opposite of acid). Other foods, like meats, egg yolks, hard/processed cheeses, and grains, can increase the levels of acid in your blood. This does not necessarily mean you have to remove them from your diet entirely – a focus on eating less of these acid-producing foods can help.

Sometimes adding more fruits, vegetables, and/or plant-based proteins to your diet can impact other health conditions you may have like hyperkalemia (high potassium levels), hyperphosphatemia (high phosphorus levels), or diabetes. So, working with a kidney dietitian can help you find the best types of adjustments to your diet based on your stage of CKD, other health conditions, and personal preferences.

Medications

If changes to your diet are not enough, your healthcare professional may recommend adding medication. The most commonly prescribed medications (supplements) for metabolic acidosis include:

• Sodium bicarbonate tablets
• Sodium bicarbonate powder (also known as baking soda)
• Sodium citrate solution (liquid)
• Potassium citrate tablets
• Potassium citrate solution (liquid)
• Potassium citrate powder [individual packets]

These medicines work by increasing the amount of base in your blood (to cancel out the acid). The powder forms of these medications should be dissolved (mixed) in 8-12 ounces of water or mixed with food before consuming. Also, potassium-based products are usually not used for people living with CKD unless you also have hypokalemia (low potassium levels in your blood).

Questions to ask

• What are my risk factors for metabolic acidosis?
• Do any of my other health conditions increase my risk for metabolic acidosis?
• What steps can I take to lower my risk for metabolic acidosis?
• How often should I have my bicarbonate level checked?
• Are there any specific warning signs or symptoms that indicate I may need immediate medical attention?
• Can you refer me to a kidney dietitian to help me with any changes I need to make to my diet?

• Plant-Based Diets and Kidney Failure
• NKF Council on Renal Nutrition CKD Kidney Dietitian Directory

This content is provided for informational use only and is not intended as medical advice or as a substitute for the medical advice of a healthcare professional.