Should You Get a CK Test?
Yes, you should have a serum creatine kinase (CK) level checked immediately, along with thyroid function (TSH), because your muscle symptoms (shoulder/arm pain and calf weakness) occurring after increasing your statin dose are concerning for statin-associated muscle symptoms (SAMS), and CK measurement is essential to guide management decisions. 1, 2
Why CK Testing Is Indicated Now
The 2019 AHA/ACC guidelines specifically recommend measuring CK levels in individuals with statin-associated muscle symptoms to distinguish between simple myalgia and more serious myopathy. 1 Your symptoms—shoulder/arm pain and calf/leg muscle weakness—occurring after doubling your statin dose from every other day to daily represent a clear temporal relationship that warrants investigation. 2
- The American College of Cardiology recommends obtaining CK immediately when any patient on statin therapy reports muscle soreness, tenderness, pain, or weakness, and comparing it to baseline measurements. 2
- Your symptoms are not occurring every day but are "somewhat regular," which is consistent with statin-associated muscle symptoms that can be intermittent. 1, 3
Essential Laboratory Tests to Order
Beyond CK, you need a comprehensive evaluation:
- CK level (most important immediate test) 1, 2
- TSH (thyroid-stimulating hormone) - hypothyroidism predisposes to myopathy and can exacerbate statin-related muscle injury 2, 4
- Liver enzymes (ALT, AST) - to assess for hepatotoxicity 1
- Vitamin D (25-OH) level - deficiency increases muscle symptom risk 2
- Serum creatinine - renal impairment increases myopathy risk 2
How to Interpret Your CK Results
The management depends entirely on your CK level and symptom severity:
If CK is less than 4 times upper limit of normal (ULN):
- Continue your statin while monitoring symptoms closely 1
- Recheck CK if symptoms worsen 1
- Consider dose reduction or alternate-day dosing if symptoms persist 1
If CK is 4-10 times ULN with symptoms:
- Follow CK levels weekly and monitor symptoms closely 2
- Consider stopping the statin temporarily and rechallenging with a lower dose or different statin once symptoms resolve 1
If CK is greater than 10 times ULN:
- Stop the statin immediately, regardless of symptom severity 1, 2
- Check renal function and monitor CK every 2 weeks until normalized 1
- This represents significant myopathy requiring immediate cessation 2
Important Caveats About Your Facial Symptoms
The left facial symptoms you mention are not typical of statin-associated myopathy, which primarily affects proximal skeletal muscles (shoulders, hips, thighs). 1, 3 This raises two possibilities:
- The facial symptoms may be unrelated to the statin and require separate neurological evaluation
- You should specifically describe these facial symptoms to your doctor (weakness? numbness? pain?) as they may indicate a different process
Common Pitfall to Avoid
Do not dismiss normal or minimally elevated CK in the presence of your muscle symptoms. 2 The 2016 ESC/EAS guidelines note that symptomatic patients can have statin-induced myopathy even with CK less than 4 times ULN. 1 Your symptoms alone warrant management adjustments, regardless of CK level. 1, 3
What Happens After Testing
If your CK is elevated or symptoms persist despite normal CK:
- Stop the statin temporarily until symptoms completely resolve 2, 3
- Once asymptomatic, rechallenge with a different statin at a lower dose (such as pravastatin or fluvastatin, which have lower myopathy risk) 2, 3
- Alternative strategies include alternate-day dosing of your current statin or adding ezetimibe to allow lower statin doses 1, 3
The key point: Your instinct to get CK tested is correct. The temporal relationship between increasing your statin dose and developing muscle symptoms is exactly the scenario where guidelines mandate CK measurement to guide safe management. 1, 2