Additional Laboratory Tests with Lipoprotein Profile
When ordering a lipoprotein profile, you should add apolipoprotein B (apoB) and lipoprotein(a) [Lp(a)] as individually orderable tests, particularly in patients with hypertriglyceridemia, family history of premature ASCVD, or unexplained cardiovascular disease. 1
Standard Lipid Panel Components
The baseline lipid panel should include:
- Total cholesterol
- LDL-C (calculated using the NIH equation, not Friedewald)
- HDL-C
- Non-HDL-C (total cholesterol minus HDL-C)
- Triglycerides
Both fasting and nonfasting samples are acceptable for most situations, as they have similar prognostic value 2, 1. Nonfasting is more convenient and reasonable for initial screening and baseline assessment before statin initiation.
When to Add Apolipoprotein B (apoB)
Add apoB when:
- Triglycerides ≥200 mg/dL - This is the primary indication, as apoB measurement has advantages in hypertriglyceridemia 2
- Patients with metabolic syndrome or diabetes
- When LDL-C is very low (<70 mg/dL), where Friedewald calculation becomes unreliable 2
- To assess residual cardiovascular risk despite optimal LDL-lowering treatment, especially with mild-to-moderate hypertriglyceridemia (2-10 mmol/L) 3
Clinical threshold: ApoB >130 mg/dL corresponds to LDL-C ≥160 mg/dL and constitutes a risk-enhancing factor 2. Persistent elevation should guide more aggressive treatment.
When to Add Lipoprotein(a) [Lp(a)]
The 2026 ACC/AHA guidelines now recommend testing Lp(a) at least once in all adults 4, 5. This represents a major shift toward universal screening.
Specific indications include:
- Family history of premature ASCVD (strongest indication) 2
- Personal history of ASCVD not explained by major risk factors 2
- Initial lipid screening in all patients (measure once in lifetime) 1
- Women with hypercholesterolemia (though improvement in risk prediction is minimal) 2
Clinical threshold: Lp(a) ≥50 mg/dL or ≥125 nmol/L is considered a risk-enhancing factor 2, 1. Approximately 1 in 5 individuals have levels at or above this threshold 4.
Important caveat: Lp(a) levels are highly heritable and stable over time, so repeat measurements are not indicated 1. Use assays that report in molar units (nmol/L) for better standardization 1.
Fasting vs. Nonfasting Considerations
Order fasting lipids when:
- Triglycerides >4.52 mmol/L (or >9.04 mmol/L if using NIH equation) 1
- Patients undergoing treatment monitoring
- Triglycerides >1.50 mmol/L in patients being monitored for LDL-C-lowering therapy response 1
- Family history of premature ASCVD or suspected genetic hyperlipidemia 2
Common Pitfalls to Avoid
Don't use Friedewald equation - Switch to NIH/Sampson equation for LDL-C calculation, especially at lower LDL-C levels 1, 6
Don't ignore non-HDL-C - This should be reported on all standard lipid panels and is particularly useful for assessing remnant lipoprotein cholesterol 3
Don't order apoB and Lp(a) reflexively - These should be individually orderable tests, not part of routine panels 1, though the threshold for Lp(a) testing is now very low given universal screening recommendations
Don't repeat Lp(a) - Once measured, it doesn't need rechecking unless there's a specific clinical indication
Laboratory reliability matters - ApoB measurement may not be reliable in some laboratories and carries extra expense 2, so ensure your lab has appropriate standardization
The evidence strongly supports moving beyond basic lipid panels in high-risk patients, with the most recent guidelines (2026) particularly emphasizing universal Lp(a) testing 4, 5.