Linear Analysis of Autonomic Activity and Its Correlation with Creatine Kinase-MB in Overt Thyroid Dysfunctions

Area of Science:

• Endocrinology
• Cardiology
• Neurology

Background:

• Thyroid dysfunction can disrupt autonomic nervous system activity, potentially leading to cardiovascular complications.
• Myopathy, often linked to elevated creatine kinase (CK), is a known complication of thyroid disorders.
• The study investigates whether cardiac abnormalities, specifically elevated CK-MB, occur in thyroid dysfunction.

Purpose of the Study:

• To examine the relationship between thyroid profile, creatine kinase (CK), and its MB isoform (CK-MB) with heart rate variability (HRV) in hypothyroid and hyperthyroid patients.
• To determine if cardiovascular changes in thyroid dysfunction are associated with cardiac muscle damage or autonomic imbalance.

Main Methods:

• Assessed autonomic activity using 5-minute heart rate variability (HRV) in 35 hypothyroid, 35 hyperthyroid patients, and 25 controls.
• Measured serum thyroid profile, total creatine kinase (CK-NAC), and CK-MB levels in all participants.
• Analyzed correlations between CK, CK-MB, thyroid hormones, and HRV parameters.

Main Results:

• Hypothyroid and hyperthyroid patients exhibited reduced HRV compared to controls.
• Serum CK levels were significantly higher in hypothyroid patients than in hyperthyroid patients and controls.
• No significant differences in CK-MB levels were found across the three groups, and CK-MB showed no significant correlation with thyroid profile or HRV.

Conclusions:

• Cardiovascular changes in thyroid dysfunction are likely due to autonomic imbalance rather than direct cardiac muscle injury.
• Elevated CK levels in hypothyroid patients suggest significant skeletal muscle involvement.
• HRV parameters were negatively correlated with CK in hypothyroid patients, further supporting skeletal muscle impact.