Serum creatine kinase and lactate dehydrogenase activities in patients with thyroid disorders.

BACKGROUND AND OBJECTIVES: There is the recognition of a pattern of elevations of serum enzymes in hyperthyroid and hypothyroid patients. The aims of this study were to determine the activities of serum creatine kinase (CK) and lactate deydrogenase (LDH) in thyroid disorders, and to evaluate the relationship between CK, LDH and FT4, and TSH levels.

MATERIALS AND METHODS: In this retrospective study, thyroid function tests, serum CK and LDH activities were obtained from the medical records of newly diagnosed hyperthyroid and hypothyroid patients attending the Endocrinology Clinic at the University Hospital of the West Indies from 2005- 2009.

RESULTS: Elevation of CK activity was found in 5 patients (28%, 5/18) with overt hypothyroidism and in 12 patients (24.0%, 12/50) with subclinical hypothyroidism. The mean CK activity in subclinical hypothyroid patients was 179.80 ± 125.68 U/L compared with 389.901 ± 381.20 U/L in overt hypothyroid patients. The elevation of LDH activity was found in 6 patients (33.3%, 6/18) with overt hypothyroidism and in 37 patients (74.0%, 37/50) with subclinical hypothyroidism. In the hypothyroid patients, a positive correlation was found between CK activity and TSH (r = 0.292, P = 0.015), and a negative correlation between CK activity and FT4 (r = - 0.325, P = 0.007); and between FT4 and TSH (r = - 0.371, P = 0.002).

CONCLUSION: The significant elevation in serum CK and LDH activities indicates that these can be used as parameters for screening hypothyroid patients but not hyperthyroid patients.