Interrelationship between Serum Muscle Enzymes and a Low T₃ in Anorexia Nervosa

To determine the interrelationship between muscle dysfunction and a low T₃ state, both seen in anorexia nervosa, we studied the relationship between the degree of muscle involvement, as assessed by the circulating concentration of the three muscle indicators (CPK, GOT and LDH), and serum T₃ in thirty-three patients when they were admitted to the hospital. We also studied the malnutritional state, as assessed by their body weight or serum GH, serum potassium and the degree of hyperactivity exhibited. Additionally, another twelve patients were studied in order to explore the mounding phenomenon which is typically elicited in hypothyroidism. The logarithms of serum CPK and GOT correlated only with the serum T₃ concentration (r= - 0.35, p<0.05; r=-0.41, p<0.05; respectively). The logarithm of serum LDH highly correlated with serum T₃, the percentage of ideal body weight, and the logarithm of serum GH (r=- 0.55, p<0.01; r= - 0.66, p<0.001; r=0.43, p<0.05; respectively). The mounding phenomenon was elicited in ten out of twelve patients. In conclusion, it was implied that a low T3 state was associated with an increase in serum muscle indicators and thus with muscle dysfunction encountered in anorexia nervosa.