T3 IS AS GOOD A POINTER OF CREATINE KINASE LEVELS IN EUTHYROIDS AS T4 IS IN HYPOTHYROIDS

Aim: Hypothyroidism is one of the commonest metabolic diseases which afflicts females more than males and is often associated with myopathy. Reports on relationship of muscle-markers with thyroid hormones in the (a) euthyroid population in general and (b) hypothyroid population in India are scarce. Materials and Methods: A randomized case-control study on the female population for which 60 hypothyroids and 30 euthyroid controls were selected. Total triiodothyronine (T₃), thyroxine (T₄), thyroid stimulating hormone (TSH) and two muscle markers – lactate dehydrogenase (LDH) and creatine kinase (CK) were measured from serum samples using automated analyzers.  Results:  CK was 71% higher and LDH 23.5% higher in hypothyroids than in euthyroid controls. CK correlated well with T₄ in hypothyroids (r= – 0.68, p<0.0001) and T₃ in euthyroids (r= 0.62, p= 0.003) but to a lesser extent with others viz. T₃ in hypothyroids (r= -0.46, p= 0.0002), T₄ in euthyroids (r= -0.49, p= 0.007) and TSH both in hypothyroids and euthyroids (r= 0.43, p= 0.0006; r= -0.40, p= 0.03 respectively).  LDH correlated weakly with total T4 (p=0.28, r=0.03) in hypothyroids but showed no other statistically significant association.Conclusions: CK is satisfactorily indicated by total T₃ in euthyroid and T₄ in hypothyroid females. TSH is a weaker indicator.