What Is an Aldolase Test?

Written by Hirania Luzardo
Medically Reviewed by Jabeen Begum, MD on September 09, 2025
4 min read

An aldolase test (ALS) is a blood test that measures the level of an enzyme called aldolase in your blood. Your doctor may use it to diagnose muscle diseases or to monitor the effectiveness of your treatment.

Aldolase helps your body turn sugar into energy. Most of it is stored in your muscles and liver. When these cells are damaged, they release aldolase into your blood. Measuring the amount of aldolase in your bloodstream can help doctors detect muscle or liver problems.

‌If you have muscle weakness or myalgia (muscle pain), your doctor will want to know if your symptoms are due to a problem with your muscles or your nerves. A high amount of ALS in your blood can signal muscle damage. If the problem is in the nervous system, the amount of aldolase in your blood will not change.

‌You may need to stop eating and drinking for about eight hours before the blood test. Your doctor will let you know if you should stop any of your medicines to keep them from affecting the test results.

You might also need to avoid intense exercise for several days before the test. Long-lasting exercise can raise the level of aldolase in your blood and affect your test results.

‌A lab tech will put a very small needle in a vein in your arm. They will draw about 1 milliliter of blood into a little plastic tube called a vial. The vial will be sent off for testing. You will probably get results within a few days.

‌The normal range for aldolase can be a little higher or lower depending on your age and gender. Generally, the normal range for adults is between 1.0 and 7.5 units per liter.

The normal amount of aldolase in the blood is higher in children. For those younger than 18 years, anything under 14.5 units per liter is considered normal.

‌An increased level of aldolase in the blood is sometimes a sign of muscle disease, such as:

Duchenne muscular dystrophy (DMD). It is a genetic disorder, meaning it is caused by a change (mutation) in the person’s DNA. Symptoms typically start when a child is 2 or 3 years old. The first symptom is often muscle weakness, which can make it hard for the child to walk, run, and jump.

Other early signs can include delays in learning to sit, stand, or speak. DMD eventually causes muscle atrophy as well as heart and lung problems. Some medications can help manage DMD symptoms.‌

Limb-girdle muscular dystrophy. It is also a genetic disorder that causes weakness and wasting of the muscles around the shoulders and hips. Symptoms can include walking with a waddling gait, difficulty getting up out of a chair, or trouble climbing stairs.

The goal of treatment is to help ease symptoms. Treatment options include physical therapy and occupational therapy to strengthen muscles and prevent contractures, which are overly tight muscles that limit your range of motion.

Dermatomyositis. It is an autoimmune disease, which means that the immune system is attacking healthy cells instead of just fighting off invaders like viruses.

Signs of dermatomyositis include a red rash around your eyelids, red or purple bumps on your joints, and muscle weakness in your arms and legs.

Polymyositis. It is another rare autoimmune disease that causes muscle weakness. While dermatomyositis affects the muscles of the limbs, polymyositis typically causes weakness in the muscles of the neck, back, shoulders, and hips. It can also cause falls, a dry cough, and difficulty swallowing.

Symptoms most often start when you’re an adult and come on gradually. Medications can help reduce symptoms. Physical therapy can strengthen your muscles and improve your flexibility. Speech therapy can also help with swallowing difficulties associated with this condition.

A low aldolase level usually isn’t considered a medical concern. It often means there’s no active muscle or liver damage releasing the enzyme into your blood. Doctors mainly use the aldolase test to detect or monitor muscle disease when levels are high, such as in muscular dystrophies or myopathies.

What is the difference between creatine kinase (CK) and aldolase?

CK and aldolase are both enzymes that doctors measure in your blood, but they offer slightly different information. CK is the test most often used to check for muscle injury or disease because it rises quickly when muscle is damaged. Aldolase can also show muscle problems, but doctors don’t use it as often because CK is usually more accurate and reliable.

What causes aldolase deficiency?

Aldolase deficiency is a rare genetic disorder. It happens when you inherit mutations in the ALDOA gene, which tells your body how to make the aldolase enzyme. If you don’t have enough working aldolase, your muscles and red blood cells can’t break down sugar (glucose) properly to make energy.

What is aldolase for myositis?

If you have myositis, a disease that causes muscle inflammation, your aldolase levels may rise when your muscles get damaged. Your doctor may order an aldolase test, along with other blood tests such as creatine kinase, to help diagnose myositis or to check how active it is.