A case control study of the relationship between persistent serum creatine kinase elevation and polyneuropathy

Area of Science:

• Neurology
• Clinical Biochemistry

Background:

• Elevated creatine kinase (CK) levels have been anecdotally linked to neuropathy.
• The underlying mechanisms connecting hyperCKemia and peripheral nerve dysfunction remain unclear.

Purpose of the Study:

• To investigate whether peripheral nerve function is impaired in individuals with persistent high CK levels (hyperCKemia) compared to controls.
• To explore potential associations between CK levels and markers of glucose metabolism.

Main Methods:

• Population-based study (Tromsø study, Norway) including individuals with persistent hyperCKemia (n=113) and matched controls (n=128).
• Assessment of neuropathy using the Neuropathy Impairment Score (NIS).
• Electrophysiological evaluation including nerve conduction studies (NCS) and electromyography (EMG).

Main Results:

• The hyperCKemia group exhibited a higher NIS score than controls (p=0.050).
• NCS revealed decreased tibial nerve motor action potential amplitude and conduction velocity, and increased F-wave latency in the hyperCKemia group.
• Reduced sensory nerve amplitudes (median, ulnar, sural) and increased motor unit potential amplitude on EMG were observed in the hyperCKemia group.
• CK levels showed a positive correlation with glycated hemoglobin and non-fasting glucose in the hyperCKemia group.

Conclusions:

• Persistent hyperCKemia is associated with impaired peripheral nerve function, including length-dependent polyneuropathy.
• The exact mechanisms are unknown but may involve CK leakage and glucose metabolism.
• Further research is needed to elucidate the relationship between CK, glucose metabolism, and neuropathy.