Apolipoprotein B (ApoB) — Serum
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| mg/dL | 52 – 163 | 51 – 81 | 66 – 188 | 85 – 238 |
Apolipoprotein B (ApoB) is the structural apolipoprotein of all atherogenic particles (VLDL, IDL, LDL, and lipoprotein(a)). ApoB reflects particle number rather than cholesterol content and rises progressively during normal pregnancy.
Physiologic gestational hyperlipidemia increases ApoB especially in the 2nd and 3rd trimesters. Values at the upper end of pregnancy-specific ranges may still be normal.
Pregnancy physiology and interpretation
- Pregnancy increases total cholesterol, LDL-C, triglycerides, and ApoB as part of normal metabolic adaptation.
- Late-pregnancy ApoB values may exceed nonpregnant upper limits without indicating dyslipidemia.
- Marked elevation early in pregnancy may indicate underlying primary hyperlipidemia or diabetes.
- Low ApoB is uncommon and suggests liver disease, severe malnutrition, or rare genetic disorders.
Causes of High Apolipoprotein B
Pregnancy-related
- Normal gestational hyperlipidemia.
- Gestational or pregestational diabetes / insulin resistance.
- Obesity or metabolic syndrome.
- Primary hyperlipoproteinemias (familial combined hyperlipidemia, some FH types).
- Nephrotic-range proteinuria.
- Hypothyroidism, Cushing syndrome, glucocorticoid therapy.
General causes
- Primary genetic dyslipidemias.
- Type 2 diabetes, metabolic syndrome.
- Chronic kidney disease with proteinuria.
- Cholestatic liver disease.
- High-saturated-fat diet; excessive alcohol use.
Consistently elevated ApoB indicates high atherogenic particle burden. Management during pregnancy should be individualized with MFM and lipidology input.
Causes of Low Apolipoprotein B
Pregnancy-related
- Advanced liver disease with impaired synthesis.
- Severe malnutrition or malabsorption.
- Potent lipid-lowering medications (rare in pregnancy).
General causes
- Familial hypobetalipoproteinemia or abetalipoproteinemia.
- Severe liver disease.
- Chronic malnutrition or wasting disorders.
- Malabsorption syndromes.
- High-intensity lipid-lowering therapy.
Markedly low ApoB warrants evaluation for hepatic dysfunction, malabsorption, or inherited disorders.
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table. Obstet Gynecol. 2009;114:1326-31.
- Wallach J. Interpretation of Diagnostic Tests. 8th ed.
- Fischbach FT, Dunning MB. Manual of Laboratory and Diagnostic Tests. 7th ed.