EVALUATION OF SERUM CREATINE PHOSPHOKINASE AND LACTATE DEHYDROGENASE AS BIOMARKERS OF SKELETAL MUSCLE INVOLVEMENT IN HYPOTHYROIDISM

Hypothyroidism is a common endocrine disorder characterized by insufcient thyroid hormone production, affecting multiple organ systems including skeletal muscles. Myopathy in hypothyroidism often remains underdiagnosed, necessitating reliable biomarkers for early detection. Present study evaluates serum Creatine Phosphokinase (CPK) and Lactate Dehydrogenase (LDH) as potential biomarkers for skeletal muscle involvement in hypothyroidism. This observational cross-sectional study included 150 patients with hypothyroidism (56 with overt and 94 with subclinical hypothyroidism) attending a tertiary care center. Venous blood samples were collected following standardized protocols. Thyroid function tests (TSH, T₃, T₄) were performed using ELISA, while serum CPK and LDH activities were measured using modied IFCC methods. Patients with conditions affecting muscle enzyme levels were excluded. Statistical analysis included correlation coefcients, regression analysis, and t-tests. Results revealed signicantly higher levels of serum CPK and LDH in overt hypothyroidism compared to subclinical hypothyroidism (p<0.001 and p=0.002, respectively). A larger proportion of patients with overt hypothyroidism exhibited elevated enzyme levels than those with subclinical hypothyroidism. Correlation analysis demonstrated signicant positive associations between serum TSH and CPK (p<0.001), while signicant negative correlations were observed between thyroid hormones and muscle enzymes. Regression analysis conrmed these relationships, with thyroid hormone levels explaining a signicant portion of the variation in enzyme concentrations. These ndings suggest that serum CPK and LDH can serve as valuable biomarkers for detecting skeletal muscle involvement in hypothyroidism, particularly in overt cases, potentially improving early diagnosis and management of hypothyroid myopathy.