Serum Creatinine in Pregnancy: A Systematic Review

Abstract

Introduction Standard assessment of renal function in pregnancy is by measurement of serum creatinine concentration yet normal gestational ranges have not been established. The aim of this systematic review was to define the difference in serum creatinine in a healthy pregnancy compared with concentrations in nonpregnant women to facilitate identification of abnormal kidney function in pregnancy. Methods Medline, PubMed, Embase, Web of Science, theses, key obstetric texts, and conference proceedings were searched to July 2017. Eligible studies included quantification of serum creatinine concentration in a pregnant cohort, with either a reported local laboratory reference range or matched quantification in a nonpregnant cohort. The outcomes of interest were the mean and upper reference limits for creatinine in pregnancy, measured as a ratio of pregnant:nonpregnant values. Study heterogeneity was examined by meta-regression analysis. Results Forty-nine studies were identified. Data synthesis included 4421 serum creatinine values in pregnancy, weighted according to cohort size. Mean values for serum creatinine in pregnancy were 84%, 77%, and 80% of nonpregnant mean values during the first, second, and third trimesters, respectively. The 97.5th centile (upper limit of the 95% reference range) for serum creatinine in pregnancy was 85%, 80%, and 86% of the nonpregnant upper limit in sequential trimesters. Conclusion Based on a nonpregnant reference interval of 45–90 μmol/l (0.51–1.02 mg/dl), a serum creatinine of >77 μmol/l (0.87 mg/dl) should be considered outside the normal range for pregnancy. Future work can use this value to explore correlation of adverse pregnancy outcomes with serum creatinine concentration. PROSPERO registration: CRD42017068446

Evaluation of Selected Renal Markers in Hypertensive Subjects in Ekiti State, Nigeria

“…This may be an indication of renal involvement because serum creatinine has proven to be useful in the detection and assessment of acute kidney injury and chronic kidney disease. [10,11] The findings are similar to other reports which showed that creatinine levels were significantly higher in hypertensive subjects. [31,32] The study also recorded a positive significant correlation of urea and creatinine in hypertensive subjects and control.…”

“…Serum creatinine is used in the detection and assessment of acute kidney injury and chronic kidney disease. [10,11] Creatinine is a by-product of energy metabolism that is filtered from the blood by kidneys and is excreted into the urine. [12] Creatinine is removed from the body entirely by the kidneys and if kidney function is abnormal, creatinine level will increase in the blood.…”

The Changing Landscape of Acute Kidney Injury in Pregnancy from an Obstetrics Perspective

“…Though there have been several studies that aimed at defining the reference values for serum creatinine, none are considered accurate in pregnancy [23,25,26]. A recent systematic review found that, using a nonpregnant reference interval of 45–90 mmol/L (0.51–1.02 mg/dL), a serum creatinine higher than 77 mmol/L (0.87 mg/dL) should be considered pathological, outside the normal range for pregnancy [23] (Table 1).…”

“…The international consensus classifications mentioned above and illustrated in Table 3 and Table 4 are used for defining and staging AKI in non-pregnant patients and cannot be extrapolated to pregnancy. The rapid deterioration of kidney function that characterizes AKI has been variably defined in pregnancy, either as an increase in serum creatinine over 80 mg/dL, doubling in serum creatinine levels, oliguria of <400 mL/24 h or the need of dialysis [23,66,67]. The lack of consensus in PR-AKI definitions arises from the physiological variability in the cardiovascular haemodynamics and renal function changes in the pregnant population.…”

“…Whereas in non-pregnant patients, glomerular filtration rate (GFR) estimated from serum creatinine levels is routinely used to evaluate kidney function, in pregnancy, the use of this renal variable is less accurate, when GFR consistently underestimate renal function. Furthermore, in comparison to the non-pregnant reference interval of 0.51–1.02 mg/dL, the serum creatinine levels are overall lower in pregnancy, with values in the third trimester as low as 0.4–0.8 mg/dL, due to a combination of physiological alterations that include blood volume expansion, hyperfiltration, and decrease in oncotic pressure [23,65]. In addition, the reference values of serum creatinine in pregnancy are still under debate.…”