Differential Diagnosis for a 4-year-old Female with Elevated CK on Two Separate Occasions

Single Most Likely Diagnosis

• Muscular Dystrophy: This is a group of inherited disorders characterized by progressive muscle weakness and degeneration. Elevated creatine kinase (CK) levels are a hallmark of muscular dystrophy, particularly Duchenne muscular dystrophy, which is the most common form in children. The consistent elevation of CK on two separate occasions strongly suggests a muscular origin for the elevated enzyme levels.

Other Likely Diagnoses

• Viral Myositis: This condition involves inflammation of the muscles due to a viral infection, which can lead to elevated CK levels. It's a common cause of muscle pain and elevated CK in children.
• Physical Trauma or Overexertion: Muscle injury from physical trauma or overexertion can cause CK levels to rise. In a child, this could be due to a fall, sports injury, or even vigorous play.
• McArdle Disease (Glycogen Storage Disease Type V): Although less common, this genetic disorder affects the muscle's ability to break down glycogen for energy, leading to elevated CK levels during or after exercise.

Do Not Miss Diagnoses

• Dermatomyositis: An inflammatory disease characterized by skin rash and muscle weakness. Elevated CK levels are common, and early diagnosis is crucial for effective treatment.
• Toxic Myopathy: Certain medications and toxins can cause muscle damage, leading to elevated CK levels. Identifying and removing the causative agent is critical.
• Inflammatory Myopathies: Conditions like polymyositis can present with elevated CK levels and require prompt diagnosis and treatment to prevent long-term muscle damage.

Rare Diagnoses

• Mitochondrial Myopathies: A group of disorders affecting the mitochondria, which can lead to muscle weakness and elevated CK levels. These conditions are rare and often present with other systemic symptoms.
• Lysosomal Storage Diseases: Certain diseases, such as Pompe disease, can cause muscle damage and elevated CK levels due to the accumulation of glycogen in lysosomes.
• Congenital Myopathies: A diverse group of muscle disorders present at birth, which can cause muscle weakness and may have elevated CK levels, although this is less common.

Each of these diagnoses has a different approach to management and treatment, emphasizing the importance of a thorough diagnostic workup to determine the underlying cause of elevated CK levels in a child.