pH-adjusted ionized calcium

What’s a Normal Blood pH and What Makes It Change?

A quick introduction to the pH scale

The pH scale measures how acidic or alkaline (basic) something is.

Your body works constantly to carefully control pH levels of blood and other fluids. The body’s pH balance is also called the acid-base or acid-alkaline balance. The right pH levels are needed for good health.

The pH scale ranges from 0 to 14. The readings are based around a pH of 7, which is neutral (like pure water):

• A pH below 7 is acidic.
• A pH higher than 7 is alkaline or basic.

This scale might seem small, but each level is 10 times bigger than the next. For example, a pH of 9 is 10 times more alkaline than a pH of 8. A pH of 2 is 10 times more acidic than a pH of 3, and 100 times more acidic than a reading of 4.

So what’s a normal blood pH?

Your blood has a normal pH range of 7.35 to 7.45. This means that blood is naturally slightly alkaline or basic.

In comparison, your stomach acid has a pH of around 3 to 5.5Trusted Source. This makes it acidic. A low pH is good for digesting food and destroying any germs that get into the stomach.

What makes blood pH change or become abnormal?

Health problems that make your body too acidic or too alkaline are usually linked to the pH of blood. Changes in your normal blood pH might be a sign of certain health conditions and medical emergencies. These include:

• asthma
• diabetes
• heart disease
• kidney disease
• lung disease
• gout
• infection
• shock
• hemorrhage (bleeding)
• drug overdose
• poisoning

Blood pH balance

Acidosis is when your blood pH drops below 7.35 and becomes too acidic. Alkalosis is when your blood pH is higher than 7.45 and becomes too alkaline. The two main organs that help balance the pH of blood are the:

• Lungs. These organs remove carbon dioxide through breathing (respiration).
• Kidneys. These organs remove acids through urine (excretion).

The different types of blood acidosis and alkalosis depend on the cause. The two main types are:

• Respiratory. This type occurs when the change in blood pH is caused by a lung or breathing condition.
• Metabolic. This type occurs when blood pH changes are due to a kidney condition or issue.

Testing blood pH

A blood pH test is a normal part of a blood gas test or arterial blood gas (ABG) test. It measures how much oxygen and carbon dioxide is in your blood.

Your doctor might test your blood pH as part of a regular health checkup or if you have a health condition.

Blood pH tests involve having your blood drawn with a needle. The blood sample is then sent to a lab to be tested.

Can you test at home?

An at-home blood finger-prick test won’t be as accurate as a blood pH test at your doctor’s office.

A urine pH litmus paper test won’t show your blood’s pH level, but it may help show that something is off balance.

Causes of blood pH changes

High blood pH

Alkalosis happens when your blood pH is higher than the normal range. There are several causes of high blood pH.

An illness can temporarily raise your blood pH. More serious health conditions can also lead to alkalosis.

Losing too much water from your body can increase blood pH. This happens because you also lose some blood electrolytes (salts and minerals) with water loss. These include sodium and potassium. Causes of fluid loss are excess:

• sweating
• vomiting
• diarrhea

Diuretic drugs and other medications may cause you to urinate too much leading to high blood pH. Treatment for fluid loss includes getting plenty of fluid and replacing electrolytes. Sport drinks can sometimes help with this. Your doctor may also stop any medications that cause fluid loss.

Kidney problems

Your kidneys help to keep your body’s acid-base balance. A kidney problem can lead to high blood pH. This may happen if the kidneys don’t remove enough alkaline substances through the urine. For example, bicarbonate may be incorrectly put back into the blood.

Medications and other treatments for the kidneys help to lower high blood pH.

Low blood pH

Blood acidosis can impact how every organ in your body functions. Low blood pH is a more common medical problem than high blood pH. Acidosis can be a warning sign that a health condition isn’t properly controlled.

Some health conditions cause natural acids to build up in your blood. Acids that can lower blood pH include:

• lactic acid
• keto acids
• sulphuric acid
• phosphoric acid
• hydrochloric acid
• carbonic acid

Diet

In a healthy person, diet does not affect blood pH.

Diabetic ketoacidosis

If you have diabetes, your blood may become acidic if your blood sugar levels aren’t properly controlled. Diabetic ketoacidosis happens when your body can’t make enough insulin or use it properly.

Insulin helps move sugar from the foods you eat into your cells where it can be burned as fuel for your body.

If insulin can’t be used, your body begins breaking down stored fats to power itself. This gives off an acid waste called ketones. The acid builds up, triggering low blood pH.

Get emergency care if your blood sugar level is higher than 300 milligrams per deciliter (16 millimoles per liter).

See your doctor if you have any of these symptoms:

• excess thirst
• frequent urination
• fatigue or weakness
• nausea or vomiting
• shortness of breath
• fruity-smelling breath
• stomach pain
• confusion

Diabetic ketoacidosis is a sign that your diabetes isn’t being controlled or treated properly. For some people, it may be the first sign that you have diabetes.

Treating your diabetes will balance your blood pH. You may need daily medications, insulin injections, and a strict diet and exercise plan to stay healthy.

Metabolic acidosis

Low blood pH because of kidney disease or kidney failure is called metabolic acidosis. This happens when the kidneys don’t work properly to remove acids from your body. This raises blood acids and lowers blood pH.

According to the National Kidney Foundation, symptoms of metabolic acidosis include:

• fatigue and weakness
• loss of appetite
• nausea and vomiting
• headache pain
• fast heartbeat
• heavy breathing

Treatment for metabolic disease includes medications to help your kidneys work better. In serious cases, you may need dialysis or a kidney transplant. Dialysis is when a machine is used to clean your blood.

Respiratory acidosis

When your lungs aren’t able to move enough carbon dioxide out of your body quickly enough, blood pH is lowered. This is called respiratory acidosis. This can happen if you have a serious or chronic lung condition, such as:

• asthma (or an asthma attack)
• sleep apnea
• bronchitis
• pneumonia
• chronic obstructive pulmonary disease (COPD)
• diaphragm disorders

If you’ve had surgery, are obese, or misuse sedatives (sleeping pills) or opioid pain medications you’re also at risk for respiratory acidosis.

In some slight cases, your kidneys are able to remove the extra blood acids through urination. You may need extra oxygen and medications such as bronchodilators and steroids to help the lungs work better.