Myopathic carnitine deficiency associated with lymphocytic malignant non-hodgkin lymphoma and monoclonal immunoglobulin G-K

Summary

A 47-year-old male patient suffered from recurrent myalgia, induced by fasting or physical exercise. Later, he developed progressive muscular weakness. Serum levels of creatine phosphokinase (CPK) were elevated to approx. 400 U/l. Muscle biopsies showed lipid storage myopathy and signs of acute fiber necrosis, muscle carnitine was decreased to below 20% of controls, carnitine palmitoyl transferase (CPT) activity was normal. Carnitine was also moderately decreased in a liver biopsy and in plasma. Urine excretion of carnitine was low, no elevation of short-chain dicarboxylic acids could be found. The patient was also found to suffer from a lymphocytic malignant non-Hodgkin lymphoma, a monoclonal immunoglobulin (Ig) G-k in plasma and lymphocytic infiltration of bone marrow were demonstrated. At that time no evidence had been obtained to indicate that these two diseases could be related to each other. Autoantibodies against skeletal muscle could not be demonstrated. Absorption of L-carnitine p.o. was normal, however, plasma levels of carnitine fell again rapidly. Administration of 3 × 2 g L-carnitine per day normalized the patient's plasma carnitine levels and led to an increase of plasma short-chain acylcarnitine and ketone bodies, particularlyβ-hydroxybutyrate (B-HOB). However, no significant clinical improvement could be seen. Additional application of prednisone led to normalization of CPK serum levels.