Aldolase Cutoff Values
The upper limit of normal for serum aldolase is laboratory-specific, but abnormal values are generally defined as >6 times the upper limit of normal in the context of myositis assessment, with typical normal ranges around 130-210 ng/ml (or approximately 3-8 U/L depending on the assay method used). 1, 2
Context-Specific Cutoffs
For Myositis (Dermatomyositis/Polymyositis)
The 2016 ACR/EULAR guidelines provide specific parameters for aldolase interpretation in inflammatory myopathies:
- Normal range: Laboratory-specific upper limit of normal (ULN)
- Abnormal range for clinical assessment: Up to 6 times the ULN 1
- Pediatric myositis: Up to 6 times the ULN for juvenile dermatomyositis 2
These guidelines emphasize that aldolase is one of five muscle enzymes monitored (along with CK, LDH, AST, and ALT), and the most abnormal enzyme should be tracked for disease activity.
For General Clinical Use
Research data provides additional reference points:
- Normal healthy subjects: 130-210 ng/ml (mean 171 ± 39 ng/ml) using radioimmunoassay 3, 4
- Aldolase B (liver-specific): 21-39 ng/ml (mean 28.7 ± 8.6 ng/ml) 5
Clinical Interpretation Algorithm
When evaluating an aldolase result:
- Compare to your laboratory's specific ULN - this is the primary reference point
- For suspected myositis: Values >1-6× ULN suggest muscle inflammation; track the most abnormal enzyme over time
- For liver disease: Aldolase A >210 ng/ml suggests hepatocellular injury, particularly in malignancy 4
- For hemolysis or rhabdomyolysis: Elevated aldolase A with appropriate clinical context (fever, exercise) 6
Important Caveats
- Laboratory variability: Different assay methods yield different absolute values, so always use your institution's reference range
- Enzyme selection in myositis: The guidelines specify using the most abnormal enzyme at baseline for tracking disease activity, not necessarily aldolase alone 1
- Isoform specificity: Aldolase A (muscle/RBC), Aldolase B (liver), and Aldolase C (brain) have different tissue distributions and clinical implications 4, 5
The key principle is that "abnormal" depends on clinical context - for myositis monitoring use 6× ULN as the upper boundary of the expected range, while for general screening, any value above your laboratory's ULN warrants clinical correlation.