From the Guidelines
Normal creatine kinase (CK) levels are not explicitly defined in the provided study, but based on general medical knowledge, they typically range from 22 to 198 units per liter (U/L) for men and 24 to 170 U/L for women 1. When considering the level of Creatine Kinase (CK), it's essential to take into account various factors that can influence its levels, such as muscle mass, ethnicity, and physical activity level. For instance, Black individuals have been found to have higher CK levels than South Asian individuals and white individuals 1. Additionally, muscle mass has a positive relationship with CK activity in the blood, which can affect interpretation of CK values 1.
Key Considerations
- CK levels can be affected by various factors, including ethnicity, muscle mass, and physical activity level 1
- Elevated CK levels can indicate muscle damage or injury, but can also be seen after strenuous exercise 1
- The interpretation of CK levels is not straightforward and can be influenced by multiple factors, including the timing of blood sample collection after exercise 1
- CK levels do not necessarily peak within minutes post-exercise, but rather between 24 and 120 hours depending on the exercise modality 1
Clinical Implications
- CK levels above 3000 U·L−1 are considered abnormal or pathological and may be associated with an increased risk of acute kidney injury 1
- The use of CK levels to individualize load or recovery in athletes is problematic and lacks strong evidence to support its effectiveness 1
- Further investigation may be warranted if CK levels are significantly elevated without explanation to identify the underlying cause 1
From the Research
Normal Levels of Creatine Kinase (CK)
The normal level of Creatine Kinase (CK) can vary depending on the laboratory and the specific assay used. However, based on the provided studies, the following information can be gathered:
- The normal CK level is typically considered to be less than 170 U/L 2.
- For women, the upper reference limit of CK has been proposed to be 201 IU/L, while for men, it is 322 IU/L 3.
- Some studies use laboratory cutoff values of >180 U/L for women and >220 U/L for men to define hyperCKemia 4.
Factors Affecting CK Levels
CK levels can be affected by various factors, including:
- Muscle damage or injury, which can cause elevated CK levels 5, 6, 2.
- Peripheral neuropathy, which can be associated with hyperCKemia 4.
- Diabetic ketoacidosis, which can lead to rhabdomyolysis and elevated CK levels 2.
- Isotretinoin therapy, which can increase the risk of rhabdomyolysis and elevated CK levels 5.
Clinical Significance of CK Levels
CK levels are an important diagnostic tool for various neuromuscular diseases. However, the clinical significance of CK levels can be affected by the reference limits used. For example: