Purpose: To quantify how often creatine kinase (CK) is measured after newly elevated aminotransferases in statin users, and whether absent CK data is associated with gastroenterology (GI) referrals. Methods: Retrospective chart review of adult outpatients on statins with a first alanine/aspartate aminotransferase (ALT/AST) elevation during a 5-year period at a large health system. The primary outcome was CK testing within 30 days; secondary outcomes included CK elevation rate and GI referral within 60 days. Results: Among 806 eligible patients, 22.8% (184/806) had CK measured within 30 days (median 9 days; IQR 5–17). Of those tested, 15.8% (29/184) had CK above the upper limit of normal (ULN); 3.6% (29/806) of the entire cohort therefore had unrecognized biochemical evidence of muscle injury. None had documented rhabdomyolysis, acute kidney injury, or hospitalization. Among patients without timely CK testing (619/806), 4.7% (29/619) were referred to GI within 60 days; this proportion (3.6% of the total cohort) mirrored the fraction with CK elevation, suggesting potentially avoidable hepatic work-ups in the absence of muscle-specific testing. Conclusions: In routine practice, CK is infrequently measured after new ALT/AST elevations in statin users, yet a non-trivial subset has biochemical myopathy. Reflex CK testing at the first abnormal transaminase could improve diagnostic accuracy and reduce unnecessary GI referrals while preserving effective lipid-lowering therapy. Prospective evaluation of reflex-testing pathways and tailored statin selection/dosing is warranted.

Purpose: To quantify how often creatine kinase (CK) is measured after newly elevated aminotransferases in statin users, and whether absent CK data is associated with gastroenterology (GI) referrals. Methods: Retrospective chart review of adult outpatients on statins with a first alanine/aspartate aminotransferase (ALT/AST) elevation during a 5-year period at a large health system. The primary outcome was CK testing within 30 days; secondary outcomes included CK elevation rate and GI referral within 60 days. Results: Among 806 eligible patients, 22.8% (184/806) had CK measured within 30 days (median 9 days; IQR 5–17). Of those tested, 15.8% (29/184) had CK above the upper limit of normal (ULN); 3.6% (29/806) of the entire cohort therefore had unrecognized biochemical evidence of muscle injury. None had documented rhabdomyolysis, acute kidney injury, or hospitalization. Among patients without timely CK testing (619/806), 4.7% (29/619) were referred to GI within 60 days; this proportion (3.6% of the total cohort) mirrored the fraction with CK elevation, suggesting potentially avoidable hepatic work-ups in the absence of muscle-specific testing. Conclusions: In routine practice, CK is infrequently measured after new ALT/AST elevations in statin users, yet a non-trivial subset has biochemical myopathy. Reflex CK testing at the first abnormal transaminase could improve diagnostic accuracy and reduce unnecessary GI referrals while preserving effective lipid-lowering therapy. Prospective evaluation of reflex-testing pathways and tailored statin selection/dosing is warranted.