Abstract
Physicians frequently encounter patients with elevated serum creatine kinase (CK) levels in clinical practice without objective signs of muscle disease. The standard laboratory reference range does not reflect serum CK distribution in the population.
Moreover, physical activity can lead to a marked CK elevation; therefore, abnormal results are frequently reported in otherwise healthy subjects. Primary myopathies are rare; other causes, including metabolic disorders, endocrinopathies, and adverse drug reactions, should always be excluded first in patients with persistent CK elevation.
Muscle biopsy does not always clarify a diagnosis and should only be performed in selected cases. In recent years, modern genetic methods, referred to as next-generation sequencing, have played a role in diagnosing subclinical myopathies.
This paper aims to acquaint the reader with the issues involved in interpreting serum CK results, introduce the differential diagnosis of elevated values, and provide basic guidance on how to proceed in searching for a cause.