Absence of myoglobinuria in acute psychotic patients with marked elevation in serum creatine phosphokinase level

Elevated levels of serum creatine phosphokinase, muscular type (CK_MM) are caused primarily by diseased muscle fiber. Acute psychoses are often associated with a marked increase in serum CK_MM levels, though the reason remains obscure. Since striated muscle damage is also associated with pigmenturia and myoglobinuria, we sought to determine whether the markedly high serum CK level of acute psychosis reflects skeletal muscle damage by evaluating urinary myoglobin in affected patients. Baseline serum CK was measured on admission in 713 consecutive acute psychotic inpatients (BPRS≥40). Those showing a serum CK levels above 1000 IU/l on the first 2 days of hospitalization underwent urine collection for myoglobin testing. Patients with physical trauma or medical conditions known to cause CKemia were excluded. Twenty-five patients were eligible for the study. In no case did myoglobinuria or pigmenturia accompany the marked CKemia. There is an unexpected dissociation between the robust increase in the serum CK_MM levels and the absence of myoglobinuria in acute psychosis. Our negative finding may indicate that the serum CK threshold for myoglobinuria is very high (above 10 000 IU/l). Alternatively, psychosis-associated CKemia may be related to an unknown, nontraumatic, pathophysiological mechanism(s).