From the Guidelines
Patients on statins should have their liver function tests (LFTs) and creatine kinase (CK) levels monitored as indicated by their clinical presentation, rather than routinely. Before starting statin therapy, baseline LFTs and CK levels should be obtained [ 1 ]. After initiation, LFTs should be checked within 8-12 weeks, then not routinely thereafter, unless there are symptoms suggesting hepatotoxicity [ 1 ]. CK levels should be checked if the patient develops muscle symptoms like pain, tenderness, or weakness [ 2 ]. Additionally, lipid panels should be monitored 4-12 weeks after starting therapy to assess efficacy, then annually once stable. Fasting blood glucose or hemoglobin A1c should also be monitored periodically as statins can slightly increase the risk of diabetes. Monitoring these labs helps identify potential side effects early, including hepatotoxicity (liver damage) and myopathy (muscle damage), which are rare but serious complications of statin therapy. Some key points to consider when monitoring patients on statins include:
- Routine control of ALT thereafter is not recommended during lipid-lowering treatment [ 1 ]
- If ALT <3x ULN, continue therapy and recheck liver enzymes in 4–6 weeks [ 1 ]
- If CK becomes elevated, re-evaluate indication for statin treatment and consider stopping treatment if CK >10x ULN or if symptoms are present [ 1 ]
- In patients with increased diabetes mellitus risk or new-onset diabetes mellitus, continue statin therapy with added emphasis on adherence, net clinical benefit, and core principles of regular moderate-intensity physical activity, maintaining a healthy dietary pattern, and sustaining modest weight loss [ 2 ] The most recent and highest quality study [ 2 ] recommends against routine measurements of creatine kinase and transaminase levels in patients treated with statins.
From the Research
Laboratory Tests for Statin Therapy
The following laboratory tests should be monitored in patients taking statins:
- Liver function tests, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST) 3, 4, 5, 6
- Creatine kinase levels, although routine monitoring is not recommended in asymptomatic patients 6
Monitoring Frequency
- Liver function tests should be ordered before starting statin therapy, 12 weeks after initiation, with any dose increase, and periodically for long-term maintenance therapy 3
- However, some studies suggest that routine screening of liver function tests may not be necessary in patients on statins 7, 4
Abnormal Test Results
- Mild elevations of ALT or AST (<3 times the upper limit of normal) do not appear to lead to significant liver toxicity over time 3, 6
- Patients with transaminase levels no more than three times the upper limit of normal can continue taking statins 6
- Coexisting elevations of transaminase levels from nonalcoholic fatty liver disease and stable hepatitis B and C viral infections are not contraindications to statin use 6