What is the initial investigation for mixed dyslipidaemia?

Initial Investigation for Mixed Dyslipidemia

The initial investigation for mixed dyslipidemia should include a comprehensive lipid profile consisting of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG). 1

Core Lipid Profile Components

• A fasting lipid profile (after 12 hours fasting) is recommended for the initial evaluation of mixed dyslipidemia, as this is particularly important for accurate triglyceride measurement 1
• The baseline lipid evaluation should include:
  • Total cholesterol (TC)
  • LDL-C (calculated using the Friedewald formula or measured directly)
  • HDL-C
  • Triglycerides (TG)
  • Non-HDL-C (calculated as TC minus HDL-C)
  • TC/HDL-C ratio 1

Calculation Methods

• LDL-C can be calculated using the Friedewald formula:
  • In mmol/L: LDL-C = TC - HDL-C - TG/2.2
  • In mg/dL: LDL-C = TC - HDL-C - TG/5
  • Note: This formula is not valid when TG levels are elevated >4.5 mmol/L (>400 mg/dL), in which case direct LDL-C measurement is required 1

Additional Parameters to Consider

• Apolipoprotein B (apo B) and apolipoprotein A1 (apo A1) measurements may be considered as alternative risk markers, as they have been found to be at least as good as traditional lipid parameters 1
• The apo B/apo A1 ratio can provide additional information about cardiovascular risk 1
• Non-HDL-C is particularly useful in mixed dyslipidemia, as it estimates the total number of atherogenic particles in plasma 1

Important Considerations

• Lipid measurements should be interpreted in the context of the patient's overall cardiovascular risk profile 1
• Routine measurement of lipoprotein(a), apolipoprotein B, and other lipid markers is not recommended for initial evaluation as their value for guiding clinical decisions requires further study 1
• Be aware of potential intraindividual variation in plasma lipids (5-10% for TC, ≥20% for TG) 1

Secondary Causes Assessment

• The initial evaluation should also aim to identify potential secondary causes of mixed dyslipidemia, including:
  • Diabetes mellitus
  • Hypothyroidism
  • Nephrotic syndrome
  • Chronic kidney disease
  • Medications (e.g., antiretroviral therapies)
  • Obesity 1

Special Populations

• In patients with chronic kidney disease (CKD), a lipid profile is recommended at initial evaluation regardless of treatment status (including those on dialysis or with kidney transplantation) 1
• Patients with autoimmune chronic inflammatory conditions (rheumatoid arthritis, systemic lupus erythematosus, psoriasis) should be screened due to their increased cardiovascular risk 1
• Patients with central obesity (waist circumference ≥94 cm for European men, ≥80 cm for women) or BMI ≥25 kg/m² should be screened for dyslipidemia 1

Follow-up Considerations

• Follow-up lipid measurements are generally not required for the majority of patients after initial evaluation 1
• However, follow-up measurements may be useful in specific situations:
  • To identify low adherence to statin therapy
  • To monitor treatment efficacy
  • In cases of severe hypertriglyceridemia (>1000 mg/dL) 1

Mixed dyslipidemia, characterized by elevated triglycerides, low HDL-C, and often small dense LDL particles, is associated with increased cardiovascular risk and requires appropriate evaluation and management 2, 3.