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. 2021 Dec 8;33(5):581–598. doi: 10.1515/jbcpp-2021-0312

Table 3:

Renal changes during normal pregnancy.

Variable Direction and magnitude of change in pregnancy
Renal, calyceal, and ureter size Increases in bipolar diameter (1.0–2.5 cm); kidney volume increases by 25–30%
pH Increases by about 0.02–0.06
Renal blood flow Increases by 60–80%
Glomerular filtration rate Increases by 40–50%
Renal osmolality Decreases by approximately 10 mOsm/kg of water
Urine protein excretion Increases (up to 300 mg/day)
Serum creatinine Decreases by 16, 23 and 20% in first, second & third trimester (normal pregnancy range: 0.4–0.6 mg/dL)
Blood urea nitrogen levels Decreases to 8–10 mg/dL
Serum bicarbonate Decreases (by 4–5 mEq/L) due to compensatory respiratory alkalosis
Renal albumin excretion Increases
Renal AAG-1 excretion Increases

  • Electrolytes

  • Potassium (K)

  • Sodium (Na)

  • Bicarbonate (HcO3)

  • Chloride (Cl)

  • Phosphorus

  • Magnesium
Unchanged to mild decreases
Decreases to approximately 130–135 mmol/L
Decreases by (18–22 mmol/L is normal range in pregnancy)
Unchanged
Unchanged
Unchanged
Uric acid (serum) Decreases by approximately 130–135 mEq/L
Aldosterone Increases
Renin–angiotensin Increases

  • Renal transporters

  • BRCP

  • MRP1

  • MRP2

  • MRP3

  • MRP4

  • MRP5

  • MRP6

  • MATE1

  • MATE2-K

  • MDR1

  • OAT1

  • OAT2

  • OAT3

  • OAT5

  • OAT1A6

  • OAT2B1

  • OAT3A1

  • OATP4C1

  • OCT1

  • OCT2

  • OCT3

  • OCTN1

  • OCTN2

  • P-gp

  • PEPT1

  • PEPT2

  • URAT1
Slight increase in BRCP [20, 118]
Unchanged [81]
Decreased to unchanged expression of MRP2 in pregnant rats [81, 119]
Increased MRP3 (31–225%) [81, 118]
Decreased MRP4 [81, 89]
Decreased MRP5 [81]
Unchanged [81]
Decreased expression (by 20–40%) of MATE1 [118]
Increased expression of MATE2-K
Unchanged to slight decrease MDR1 expression [20, 118]
Decreased expression of OAT1 [118]
Increased OAT2 expression [118]
Decreased expression of OAT3 [118]
Decreased OAT5 [118]
Decreased expression [118]
Increased expression [118]
Decreased OAT3A1 [118]
Increased during pregnancy
Increased OCT1 expression [118]
Increased OCT2 expression [118]
Decreased OCT3 expression [118]
Decreased OCTN1 [118]
Decreased OCTN2 [118]
No change in renal P-gp expression during pregnancy [120]
Increased PEPT1 expression [118]
Decreased PEPT2 expression [118]
Decreased expression of URAT1 [121]

BRCP, breast cancer resistance protein; MATE, multidrug and toxin extrusion transporter; MDR, multidrug resistance protein; MRP, multidrug resistance-associated protein; OAT, organic anionic transporter; OATP, organic anionic transporting protein; OCT, organic cationic transporter; OCTN, organic cation/carnitine transporter; PEPT, peptide transporter; Pgp, P glycoprotein; URAT, urate transporter.