Total Protein (Serum)
Plasma volume expands by 40–50% during pregnancy, producing physiologic hemodilution and a predictable decrease in serum total protein and albumin. Liver synthetic function remains normal; concentrations fall due to dilution rather than decreased production.
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| g/dL | 6.7 – 8.6 | 6.2 – 7.6 | 5.7 – 6.9 | 5.6 – 6.7 |
| g/L | 67 – 86 | 62 – 76 | 57 – 69 | 56 – 67 |
Pregnancy Physiology
- Plasma volume expands by approximately 40–50% during pregnancy.
- This produces hemodilution and lower measured total protein concentration.
- Hepatic protein synthesis remains normal.
- Albumin contributes most to the observed decline.
- Reduction reflects dilution rather than impaired production.
Causes of LOW Total Protein
- Normal pregnancy-related hemodilution (most common)
- Malnutrition or inadequate protein intake
- Hyperemesis gravidarum
- Renal protein loss (nephrotic syndrome)
- Liver disease (cirrhosis, hepatitis)
- Protein-losing enteropathy
- Severe systemic illness or inflammation
Causes of HIGH Total Protein
- Hemoconcentration due to dehydration
- Monoclonal gammopathy (MGUS, multiple myeloma — rare in pregnancy)
- Chronic inflammation or autoimmune disease
- Granulomatous disease
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Obstet Gynecol. 2009;114:1326–1331.
- Cunningham FG, Leveno KJ, Bloom SL, et al. Williams Obstetrics, 26th ed. Maternal physiology.
- Lockitch G. Crit Rev Clin Lab Sci. 1997.