Hematological and Metabolic Markers in Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and results from compression of the median nerve at the wrist. Although local mechanical compression is central to the disorder, the clinical presentation of CTS varies considerably. Patients with similar nerve conduction abnormalities may report very different levels of pain, paresthesia, weakness, and functional limitation. This variability suggests that systemic metabolic and inflammatory factors may contribute to the clinical expression of CTS in addition to the degree of median nerve conduction abnormality.

Several systemic conditions, including obesity, diabetes mellitus, thyroid disease, and inflammatory disorders, are associated with CTS. Obesity and metabolic dysfunction may increase peripheral nerve vulnerability through metabolic, vascular, and inflammatory mechanisms. Low-grade systemic inflammation has also been investigated as a possible contributor to CTS. Routinely available blood measurements may therefore provide additional information about systemic factors accompanying the disorder.

In recent years, several hematological indices derived from routine blood counts have been used as markers of systemic inflammatory activity. These include the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI). Metabolic and inflammation-related measures such as triglycerides, the triglyceride-to-high-density lipoprotein cholesterol ratio (TG/HDL), the C-reactive protein-to-albumin ratio (CAR), and the C-reactive protein-albumin-lymphocyte (CALLY) index may also reflect different aspects of systemic metabolic and inflammatory burden.

This prospective cross-sectional study includes adults referred for electrodiagnostic evaluation because of symptoms suggestive of CTS. Participants with electrodiagnostically confirmed median neuropathy at the wrist constitute the CTS group, while symptomatic individuals with normal nerve conduction studies serve as the comparison group. This design allows systemic markers associated with confirmed median nerve involvement to be examined against a clinically relevant symptomatic reference group rather than against asymptomatic healthy volunteers.

Clinical examination and nerve conduction studies are performed according to the study protocol. In participants with confirmed CTS, symptom severity and functional status are assessed using the Boston Carpal Tunnel Questionnaire (BCTQ). Routine hematological, biochemical, metabolic, and inflammatory measurements are obtained from fasting blood samples, and derived inflammatory and metabolic indices are calculated from their component variables.

The study evaluates three related but distinct clinical domains: the presence of electrodiagnostically confirmed CTS, patient-reported symptom and functional burden, and electrodiagnostic severity. The main objective is to determine whether routinely available metabolic and inflammatory measures are associated differently with these domains. In particular, the study examines whether systemic metabolic or inflammatory factors may help explain differences in patient-reported burden that are not fully captured by conventional nerve conduction findings.

Inclusion criteria

• Age between 18-65 years
• Having undergone Electromyography (EMG) testing for Carpal Tunnel Syndrome (CTS)-like symptoms
• Recent complete blood count, C-Reactive Protein (CRP), and albumin available

Exclusion criteria

• Age below 18 or above 65 years
• Pregnancy
• History of wrist trauma or surgical operation
• Chronic kidney disease
• Gout
• Rheumatoid arthritis
• Connective tissue disease
• Thyroid disorders
• Acromegaly
• Polyneuropathy
• Thoracic outlet syndrome
• Brachial plexopathy
• Cervical disc herniation
• Presence of cardiac pacemaker
• Steroid use