Secondary Carnitine deficiency

What Is Secondary Carnitine Deficiency?

Secondary carnitine deficiency (SCD) is a rare condition in which carnitine levels are very low due to an underlying medical condition or medication. Carnitine is an amino acid that helps the body turn fat into energy. It also helps to transport fatty acids into the mitochondria, which is the “powerhouse” of cells and helps to produce energy.

SCD typically arises from problems with an individual’s metabolism or the medicines they take. When carnitine levels are too low, the body may not be able to use fat as fuel or produce energy efficiently, leading to physical symptoms.

Symptoms of Secondary Carnitine Deficiency

Common symptoms of secondary carnitine deficiency include fatigue, muscle weakness, muscle pain, cramps, and exercise intolerance. Some patients may also experience episodes of confusion, seizures, difficulty concentrating, and memory problems. These symptoms typically worsen after exercise or prolonged physical activity.

SCD is often diagnosed when a person experiences lactate buildup, which is high levels of lactic acid in the blood. This occurs when oxygen delivery to the body is insufficient. A person with SCD will also have a reduced level of oxygen in their tissues and organs.

Causes of Secondary Carnitine Deficiency

The most common cause of SCD is an existing medical condition such as hypothyroidism or kidney disease. Other causes include the use of certain medications such as valproic acid and certain chemotherapies. Women with polycystic ovary syndrome (PCOS) may also be at greater risk for developing SCD.


SCD is typically diagnosed using a combination of lab tests, physical exams, and medical history. Doctors may use blood or urine tests to check for carnitine levels, as well as a physical exam to look for signs of muscle weakness or fatigue.


The treatment for SCD depends on the underlying cause. For individuals with an underlying medical condition, treating that condition may help improve carnitine levels.

In some cases, doctors may prescribe medications or supplements such as L-carnitine or acetyl-L-carnitine to help improve carnitine levels. Diet changes, such as reducing intake of saturated fats and increasing intake of polyunsaturated fats, may also be recommended.


Untreated SCD can lead to serious complications, including changes in heart rate, difficulty breathing, seizures, coma, and even death. For this reason, it is important to seek medical attention if you suspect you or a loved one may have SCD.