Variation of serum creatine kinase (CK) levels and prevalence of persistent hyperCKemia in a Norwegian normal population. The Tromsø Study

Are the currently used reference intervals for creatine kinase (CK) reflecting the general population? The Tromsø Study

“…In men ≥ 50 years, however, we found a signifi cantly higher URL CK (90 % CI) compared to NORIP; 340 (299 -372) vs. In a recent publication from our group, we found the prevalence of incidentally elevated CK to be 4.3 % in women and 6.5 % in men (9) . After standardized control analyses, the prevalence of hyperCKemia based on NORIP references were reduced to 1.3 % in women and 0.77 % in men < 50 years (9) .…”

“…In a recent publication from our group, we found the prevalence of incidentally elevated CK to be 4.3 % in women and 6.5 % in men (9) . After standardized control analyses, the prevalence of hyperCKemia based on NORIP references were reduced to 1.3 % in women and 0.77 % in men < 50 years (9) . In men ≥ 50 years, the hyperCKemia prevalence was 1.8 % (9) .…”

“…In men ≥ 50 years, the hyperCKemia prevalence was 1.8 % (9) . Given a normalization rate of 70 % after standardized control analysis in incidentally detected CK elevation (9) , this may indicate that the URL NORIP values have been set too low in elderly men. After exclusion of 46 % of individuals with possible causes of hyperCKemia in the present study, the higher URL CK found in men ≥ 50 years compared to NORIP can hardly be explained by undetected neuromuscular disorders.…”

“…In subsequent standardized control analysis, about 70 % normalized, giving a prevalence of persisting hyperCKemia of 1.3 % and illustrating the great variability of this biological marker (9) .…”

“…A number of 562 out of 686 individuals with incidentally elevated CK values according to the NORIP reference intervals met a standardized CK control analysis 3 days after refraining from use of alcohol, leisure physical activity, muscular training, physiotherapy, acupuncture or any muscular damage (9) . Data from the standardized CK controls were included after fi rst excluding 143 individuals owing to use of statins or those reporting hypothyroidism or kidney disease.…”