Renal Changes in Pregnancy

Anatomical changes:- Kidneys enlarge 1–1.5 cm in length (increased blood flow and interstitial volume) - Renal pelvis and ureters dilate (physiological hydronephrosis — right > left from uterine compression of right ureter and dextrorotation of uterus) - Urinary stasis in dilated ureters and renal pelvis → increased risk for pyelonephritis (ascending UTI) - Bladder displaced anterosuperiorly → urinary frequency and nocturia (1st and 3rd trimester) Functional changes: - GFR increases 40–65% by late 1st trimester (increased renal blood flow from ↑ CO) - Result: normal serum creatinine decreases to 0.4–0.8 mg/dL (vs 0.8–1.2 non-pregnant) - A 'normal' non-pregnant creatinine of 1.0 mg/dL in a pregnant woman may indicate early renal impairment - BUN decreases (hemodilution) - Uric acid: decreases early, rises in 3rd trimester; elevated uric acid is a marker of preeclampsia Glucosuria: - Common in pregnancy (1–2+) on dipstick even with NORMAL blood glucose - Mechanism: ↑ GFR overwhelms tubular resorption capacity for glucose (tubular resorption threshold remains constant while filtered load increases) - NOT a reliable marker for GDM screening in pregnancy - Persistent 2–3+ glucosuria: check...