The creatine kinase profile of a maintenance hemodialysis population: a possible marker of uremic myopathy.

We surveyed the sera of 100 regularly hemodialyzed patients for creatine kinase (CK) and isoenzyme activity (MM, MB, BB) in order to determine the meaning of persistently elevated CK fortuitously noted in a porportion of these patients in the absence of clinical events to account for this finding. Nineteen patients (19 percent) had sustained CK elevation over the period of investigation with the skeletal muscle isoenzyme (MM) predominating. BB was within the normal range in these patients and MB exceeded 3.0% of total CK in only 2 patients. The pre-dialysis blood urea nitrogen mean for ths group was significantly higher (P < 0.02) as was the serum creatine per kilogram of dry body weight (P < 0.05) than for the group with normal CK totals. There was no significant difference in peroneal nerve conduction velocity of serum bicarbonate between these groups. CK activity also correlated significantly with predialysis blood urea nitrogen values (r = 0.52, P < .001). The deranged nitrogen metabolism previously noted in uremia leads us to conclude that the excess skeletal muscle CK may be related to the muscle wasting noted in some uremic patients.