Assessment of glomerular filtration rate during pregnancy using the MDRD formula

Joint Associations of Pregnancy Complications and Postpartum Maternal Renal Biomarkers With Severe Cardiovascular Morbidities: A US Racially and Ethnically Diverse Prospective Birth Cohort Study

Background Pregnancy complications are risk factors for cardiovascular disease (CVD). Little is known about the role of renal biomarkers measured shortly after delivery, individually or in combination with pregnancy complications, in predicting subsequent severe maternal CVD. Methods and Results This study included 566 mothers of diverse races and ethnicities from the Boston Birth cohort, enrolled at delivery and followed prospectively. Plasma creatinine and CysC (cystatin C) were measured 1 to 3 days after delivery. CVD during follow-up was defined by physician diagnoses in electronic medical records. Associations of renal biomarkers and pregnancy complications with time-to-CVD events were assessed using Cox proportional hazards models. During an average of 10.3±3.2 years of follow-up, 30 mothers developed 1 or more CVDs. Only a modest association was observed between creatinine and risk of CVD. In comparison, we found that per 0.1 mg/L increase of CysC was associated with a hazard ratio (HR) of 1.2 (95% CI, 1.1-1.4) for CVD after adjusting for covariates. Compared with those without preeclampsia and with normal CysC level (≤75th percentile), mothers with preeclampsia and elevated CysC (>75th percentile) had the highest risk of CVD (HR, 4.6 [95% CI, 1.7-17.7]), whereas mothers with preeclampsia only or with elevated CysC only did not have significantly increased CVD risk. Similar synergistic effects for CVD were observed between CysC and preterm delivery. Conclusions In this sample of US, traditionally underrepresented multiracial and multiethnic high-risk mothers, elevated maternal plasma CysC, independently and jointly with pregnancy complications, increased risk of CVD later in life. These findings warrant further investigation. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03228875.

Twenty-four-hour proteinuria levels are associated with adverse pregnancy outcomes among women with CKD

Background

Proteinuria is commonly measured to assess the renal status of chronic kidney disease (CKD) patients before the 20th week of gestation during pregnancy. High levels of proteiuria have been associated with adverse pregnancy outcomes. However, researchers have not clearly determined what baseline proteinuria levels would be associated with adverse pregnancy outcomes. This study aimed to analyse associations between proteinuria levels and adverse pregnancy outcomes among CKD patients treated with or without steroids/immunosuppressive therapy in early pregnancy.

Methods

This retrospective study included the clinical information of 557 pregnant patients with CKD from 1 January 2009 to 31 December 2021. A multivariable logistic regression analysis was conducted to evaluate the risk of adverse pregnancy outcomes across various proteinuria ranges, which were further stratified by whether the patients were receiving steroids/immunosuppressive therapy.

Results

(i) Proteinuria was assessed on 24-h urine collection. The median (quartile) baseline proteinuria levels were 0.83 g (0.20, 1.92) and 0.25 g (0.06, 0.80) in the steroids/immunosuppressive therapy and therapy-free groups, respectively. (ii) CKD patients with adverse pregnancy outcomes had significantly higher proteinuria levels in the first trimester than patients without adverse pregnancy outcomes. (iii) The risk of adverse pregnancy outcomes increased with increasing baseline proteinuria levels (P < .001). (iv) In the early-pregnancy steroids/immunosuppressive therapy group, the risk of severe preeclampsia was higher in patients with higher baseline proteinuria levels (P < .007) [odds ratio (OR) 30.86 for proteinuria ≥5.00 g/24 h]; in the therapy-free group, the risks of severe preeclampsia, very-low-birth-weight infants, early preterm birth and foetal-neonatal death were higher in patients with higher baseline proteinuria levels (OR 53.16 for proteinuria ≥5.00 g/24 h; OR 37.83 for proteinuria ≥5.00 g/24 h; OR 15.30 for proteinuria ≥5.00 g/24 h; and OR 18.83 for proteinuria ≥5.00 g/24 h, respectively; P < .001, P < .001, P < .001 and P = .006, respectively).

Conclusions

As shown in the present study, a baseline 24-h proteinuria level >1.00 g was associated with adverse maternal outcomes. Furthermore, a 24-h proteinuria level >2.00 g increased the incidence of adverse foetal events among CKD patients.

Joint associations of pregnancy complications and postpartum maternal renal biomarkers with severe cardiovascular morbidities: A US racially diverse prospective birth cohort study

Rationale & Objective

Pregnancy complications are risk factors for cardiovascular diseases (CVD). Little is known about the role of renal biomarkers measured shortly after delivery, individually or in combination with pregnancy complications, in predicting subsequent severe maternal CVD.

Methods

This study included 576 mothers of diverse ethnicities from the Boston Birth cohort, enrolled at delivery and followed prospectively. Plasma creatinine and cystatin C were measured 1-3 days after delivery. CVD during follow-up was defined by physician diagnoses in electronic medical records. Associations of renal biomarkers and pregnancy complications with time-to-CVD events were assessed using Cox proportional hazards models.

Results

During an average of 10.3±3.2 years of follow-up, 34 mothers developed one or more CVD events. Although no significant associations were found between creatinine and risk of CVD, per unit increase of cystatin C (CysC) was associated with a hazard ratio (HR) of 5.21 (95%CI = 1.49-18.2) for CVD. A borderline significant interactive effect was observed between elevated CysC (≥75th percentile) and preeclampsia. Compared to those without preeclampsia and with normal CysC level (<75 th percentile), mothers with preeclampsia and elevated CysC had the highest risk of CVD (HR=3.8, 95%CI = 1.4-10.2), while mothers with preeclampsia only or with elevated CysC only did not have significantly increased CVD risk. Similar synergistic effects for CVD were observed between CysC and preterm delivery.

Conclusions

In this sample of US, traditionally under-represented multi-ethnic high-risk mothers, elevated maternal plasma cystatin C and pregnancy complications synergistically increased risk of CVD later in life. These findings warrant further investigation.

Clinical Perspectives

What is new?Maternal postpartum elevated levels of cystatin C are independently associated with higher risk of cardiovascular diseases (CVD) later in life.Maternal pregnancy complications coupled with postpartum elevated levels of cystatin C synergistically increased future risk of CVD.What are the clinical implications?These findings, if further confirmed, suggest that women with pregnancy complications and elevated postpartum cystatin C may be at particular high risk for CVD later in life compared to women without these risk factors.

Serum creatinine and estimated glomerular filtration rate (eGFR) in early pregnancy and changes during the pregnancy

Renal functions in pregnancy undergo rapid changes, and the thresholds for normal values are a major research gap and are still debatable. The lack of prospective population-based studies with early pregnancy recruitment hampered the decision-making process on the best thresholds to be used in clinical practice. We present the serum creatinine (sCr) and sCr-based estimated glomerular filtration rates (eGFR) in early pregnancy with changes over the gestational period in a large prospective, community-based cohort, the Rajarata Pregnancy Cohort (RaPCo). We carried out a community-based prospective cohort study with 2,259 healthy pregnant women with a gestation period of less than 13 weeks and without pre-existing medical conditions. Gestational period-specific sCr and sCr-based eGFR were calculated for different age strata, and the participants were followed up until the second trimester. Renal functions of pregnant women were compared with 2.012 nonpregnant women from the same geographical area. The mean (SD) sCr of the 2,012 nonpregnant women was 62.8(12.4) μmol/L, with the 97.5th percentile of 89.0 μmol/L. Among the pregnant women, mean (SD) sCr was 55.1(8.3), 52.7(8.1), 51.1(9.1), 47.1(7.2), and 49.3 (9.9), while the 97.5th percentile for sCr was 72.4, 69.1, 70.0, 63.6, and 66.0 μmol/L respectively during the 4-7, 8-9, 10-12, 24-27 and 28-30 weeks of gestation. The average sCr value was 84.7% and 76.4% of the nonpregnant group, respectively, in the first and second trimesters. The mean eGFR was 123.4 (10.7) mL/min/1.73 m2 in the first trimester and increased up to 129.5 mL/min/1.73 m2 in the 24th week of gestation. The analysis of cohort data confirmed a significant reduction in sCr with advancing pregnancy (p<0 .001). This study provides thresholds for renal functions in pregnancy to be used in clinical practice. Clinical validation of the proposed thresholds needs to be evaluated with pregnancy and newborn outcomes.

Time to Rethink the Current Paradigm for Assessing Kidney Function in Drug Development and Beyond

Chronic kidney disease (CKD) is an important health issue that affects ~ 9.1% of the world adult population. Serum creatinine is the most commonly used biomarker for assessing kidney function and is utilized in different equations for estimating creatinine clearance or glomerular filtration rate (GFR). The Cockcroft-Gault formula for adults and "original" Schwartz formula for children have been the most commonly used equations for estimating kidney function during the last 3-4 decades. Introduction of standardized serum creatinine bioanalytical methodology has reduced interlaboratory variability but is not intended to be used with Cockcroft-Gault or original Schwartz equations. More accurate equations (for instance, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) for adults and bedside Schwartz or Chronic Kidney Disease in Children Schwartz equation for children) based on standardized serum creatinine values (and another biomarker-cystatin C) have been introduced and validated in recent years. Recently, the CKD-EPI equation refitted without a race variable was introduced. Clinical practice guidance in nephrology advocates a shift to these equations for managing health care of patients with CKD. The guidance also recommends use of albuminuria in addition to GFR for CKD diagnosis and management. Significant research with large data sets would be necessary to evaluate whether this paradigm would also be valuable in drug dose adjustments. This article attempts to highlight some important advancements in the field from a clinical pharmacology perspective and is a call to action to industry, regulators, and academia to rethink the current paradigm for assessing kidney function to enable dose recommendation in patients with CKD.

Factors Associated with the Severity of Pregnancy-Related Hypertensive Disorder: Significance of Clinical, Laboratory, and Histopathological Features

The purpose of this paper is to evaluate the association of maternal clinical and laboratory features and placental histopathological changes with disease severity in pregnancy-related hypertensive disorders. From January 2021 to December 2021, clinical and laboratory data at the time of delivery and histopathological features of the placenta were collected from pregnant women with pregnancy-related hypertensive disorders at a single institution. The women were classified according to the pregnancy-related hypertensive disorder clinical severity, and each variable was compared accordingly. Gestational age-matched normotensive groups were also compared. Univariate and multivariate regression analyses were used to identify factors influencing pregnancy-related hypertensive disorder severity. Fifty-eight pregnancies were analyzed. Maternal albumin levels before delivery (beta coefficient −0.83, p = 0.043) and increased placental syncytial knots (beta coefficient 0.71, p = 0.026) are important parameters that are closely related to disease severity in women with pregnancy-related hypertensive disorders. The combination of albumin, PAPP-A, total bilirubin, and eGFR levels appears to be optimal for predicting pregnancy-related hypertensive disorder severity.

Function and longevity of renal grafts from high-KDPI donors

BACKGROUND

High kidney-donor profile index (KDPI) kidneys have a shorter survival than grafts with lower KDPI values. It is still unclear, however, whether their shorter longevity depends on an inferior baseline function, faster functional decline, or the combination of both.

METHODS

We analyzed the estimated glomerular filtration rate (eGFR) of 605 consecutive recipients of deceased donor kidney transplants (KT) at 1, 3, 6, 12, 18, 24, 36, 48, and 60 months. Comparisons were performed among four groups based on KDPI quartile: Group I-KDPI ≤ 25% (n = 151), Group II-KDPI 26-50% (n = 182), Group III-KDPI 51-75% (n = 176), and Group IV-KDPI 〉 75% (n = 96). Linear mixed model analysis was subsequently used to assess whether KDPI was independently associated with the decline in eGFR during the first 5-years after KT. We also analyzed the incidence of delayed graft function (DGF), rejection within the first year after KT, patient survival, graft survival, and death censored graft survival based on KDPI group.

FINDINGS

High-KDPI grafts had lower eGFR immediately after KT, had a higher incidence of DGF and rejection. However, there were no signifcant differences in the adjusted rate (slope) of decline in eGFR among the four KDPI groups (P = .06). Although patient survival was signigicantly lower for recipients of high-KDPI grafts, death-censored graft survival was similar among the four KDPI groups (P = .33).

CONCLUSIONS

The shorter functional survival of high-KDPI grafts seems to be due to their lower baseline eGFR rather than a more rapid functional decline after KT.

Gestational age-specific serum creatinine can predict adverse pregnancy outcomes

Serum creatinine level (SCr) typically decreases during pregnancy due to physiologic glomerular hyperfiltration. Therefore, the clinical practice of estimated glomerular filtration rate (eGFR) based on SCr concentrations might be inapplicable to pregnant women with kidney disease since it does not take into account of the pregnancy-related biological changes. We integrated the Wonju Severance Christian Hospital (WSCH)-based findings and prior knowledge from big data to reveal the relationship between the abnormal but hidden SCr level and adverse pregnancy outcomes. We analyzed 4004 pregnant women who visited in WSCH. Adverse pregnancy outcomes included preterm birth, preeclampsia, fetal growth retardation, and intrauterine fetal demise. We categorized the pregnant women into four groups based on the gestational age (GA)-unadjusted raw distribution (Q1–4_raw), and then GA-specific (Q1–4_adj) SCr distribution. Linear regression analysis revealed that Q1-4_adj groups had better predictive outcomes than the Q1–4_raw groups. In logistic regression model, the Q1–4_adj groups exhibited a robust non-linear U-shaped relationship with the risk of adverse pregnancy outcomes, compared to the Q1–4_raw groups. The integrative analysis on SCr with respect to GA-specific distribution could be used to screen out pregnant women with a normal SCr coupled with a decreased renal function.

Prediction of Pregnancy-Induced Changes in Secretory and Total Renal Clearance of Drugs Transported by Organic Anion Transporters

Pregnancy can significantly change the pharmacokinetics of drugs, including those renally secreted by organic anion transporters (OATs). Quantifying these changes in pregnant women is logistically and ethically challenging. Hence, predicting the in vivo plasma renal secretory clearance (CLsec) and renal CL (CLrenal) of OAT drugs in pregnancy is important to design correct dosing regimens of OAT drugs. Here, we first quantified the fold-change in renal OAT activity in pregnant versus nonpregnant individual using available selective OAT probe drug CLrenal data (training dataset; OAT1: tenofovir, OAT2: acyclovir, OAT3: oseltamivir carboxylate). The fold-change in OAT1 activity during the 2nd and 3rd trimester was 2.9 and 1.0 compared with nonpregnant individual, respectively. OAT2 activity increased 3.1-fold during the 3rd trimester. OAT3 activity increased 2.2, 1.7 and 1.3-fold during the 1st, 2nd, and 3rd trimester, respectively. Based on these data, we predicted the CLsec, CLrenal and total clearance ((CLtotal) of drugs in pregnancy, which are secreted by multiple OATs (verification dataset; amoxicillin, pravastatin, cefazolin and ketorolac, R-ketorolac, S-ketorolac). Then, the predicted clearances (CLs) were compared with the observed values. The predicted/observed CLsec, CLrenal, and CLtotal of drugs in pregnancy of all verification drugs were within 0.80-1.25 fold except for CLsec of amoxicillin in the 3rd trimester (0.76-fold) and cefazolin in the 2nd trimester (1.27-fold). Overall, we successfully predicted the CLsec, CLrenal, and CLtotal of drugs in pregnancy that are renally secreted by multiple OATs. This approach could be used in the future to adjust dosing regimens of renally secreted OAT drugs which are administered to pregnant women. SIGNIFICANCE STATEMENT: To the authors' knowledge, this is the first report to successfully predict renal secretory clearance and renal clearance of multiple OAT substrate drugs during pregnancy. The data presented here could be used in the future to adjust dosing regimens of renally secreted OAT drugs in pregnancy. In addition, the mechanistic approach used here could be extended to drugs transported by other renal transporters.

Maternal plasma pro-atrial and C-type natriuretic peptide levels and their associations with cardiovascular and renal function in the second half of normal pregnancy: a longitudinal study

BACKGROUND

Physiological adaptation in pregnancy is characterized by remodeling of endocrine, cardiovascular and renal functions leading to fluid retention, volume expansion, altered cardiac loading conditions and hyperdynamic circulation. Natriuretic peptides have been used as biomarkers of cardiovascular function, but their associations with gestational age-related changes in maternal cardiac, endothelial and renal function have not been elucidated. The aim of this study was to establish longitudinal reference values for maternal plasma atrial natriuretic peptide (proANP) and C-type natriuretic peptide (CNP) and investigate their temporal association with cardiovascular and renal function in the second half of pregnancy.

METHODS

This study was a prospective longitudinal study of 53 low-risk pregnancies. Women were examined every 3-5 weeks during 22-40 weeks of gestation (252 observations). Fasting maternal blood samples were obtained to measure proANP, CNP, creatinine, cystatin C, uric acid, and fibrinogen levels. Cardiac function and systemic hemodynamics were assessed noninvasively by impedance cardiography (ICG) and vascular endothelial function by flow-mediated vasodilation of brachial artery (FMD).

RESULTS

The plasma proANP (R²adj = 0.79; P = 0.007), CNP (R2adj = 0.54; P = 0.005) decreased between 22 and 40 weeks. The creatinine (R²adj = 0.90; P < 0.001), cystatin C (R²adj = 0.93; P = < 0.001) and uric acid (R²adj = 0.83; P < 0.001) increased significantly, whereas the estimated glomerular filtration rate (R²adj = 0.93; P < 0.001) decreased with gestational age. The FMD did not change significantly but fibrinogen (R²adj = 0.79; P < 0.001) increased with advancing gestation. The maternal systemic vascular resistance index (R²adj = 0.50; P < 0.001) increased, stroke index (R²adj = 0.62; P < 0.001) decreased, whereas the cardiac index (R²adj = 0.62; P = 0.438) and thoracic fluid content (R²adj = 0.72; P = 0.132) did not change significantly with gestation. The proANP was associated with thoracic fluid content (R²adj = 0.74; P < 0.001) and fibrinogen (R²adj = 0.78; P = 0.034) but not with other variables of systemic hemodynamics, endothelial function, or renal function. The CNP was not associated significantly with parameters of cardiovascular or renal function.

CONCLUSION

Longitudinal reference values for maternal plasma proANP and CNP were established. These natriuretic peptides decreased slightly with advancing gestation, but they did not reflect the temporal physiological changes in maternal systemic hemodynamics, vascular endothelial function and renal function during the second half of pregnancy. The proANP correlated with the thoracic fluid content reflecting volume load in pregnancy.

Contextualizing Evidence for Action on Diabetes in Low-Resource Settings-Project CEAD Part-II, Strengthening the Health System: A Mixed-Methods Study Protocol

Diabetes is a major public health problem, increasingly affecting low- and middle-income countries. The project CEAD (Contextualizing Evidence for Action in Diabetes in low-resource settings) aims to evaluate the implementation of comprehensive diabetes care in two low-resource settings in Ecuador and to stimulate context-led health systems innovations to improve diabetes care and reduce inequity. The mixed-methods approach includes a 24-month retrospective study to assess the current level of implementation of comprehensive diabetes care and participants will be followed up prospectively for two years to assess changes in healthcare and clinical outcomes from the outset of the research. We will include individuals diagnosed with type-2 diabetes aged over 18 years, who are accessing diabetes care in health facilities in the study districts. Varied stakeholders (patients and family members, community members, healthcare workers and decision-makers) will interpret the underlying causes of the observed weaknesses and propose solutions to strengthen diabetes-related healthcare in focus group discussions (FG). A second set of FG will analyze perceived improvements in healthcare based on prospective cohort findings and consider the success/failure of any context-led innovations occurring throughout the research. Our study will demonstrate how evidence can be contextualized to stimulate local innovations and overcome weaknesses of diabetes-related healthcare in low resource settings.

ADIPS 2020 guideline for pre-existing diabetes and pregnancy

This is the full version of the Australasian Diabetes in Pregnancy Society (ADIPS) 2020 guideline for pre-existing diabetes and pregnancy. The guideline encompasses the management of women with pre-existing type 1 diabetes and type 2 diabetes in relation to pregnancy, including preconception, antepartum, intrapartum and postpartum care. The management of women with monogenic diabetes or cystic fibrosis-related diabetes in relation to pregnancy is also discussed.

Trimester-Specific Reference Intervals of Serum Urea, Creatinine, and Uric Acid Among Healthy Pregnant Women in Zhengzhou, China

OBJECTIVE

To verify the differences in serum levels of urea, creatinine, and uric acid (UA) between pregnant and nonpregnant women and establish specific reference intervals of serum urea, creatinine, and UA for pregnant women, and thus help for the detection of kidney disease in pregnancy.

METHODS

Based on the selection criteria, 1312 apparently healthy pregnant women and 1301 nonpregnant women were enrolled in this study. The levels of serum urea, creatinine, and UA were compared between the pregnant and nonpregnant women. The differences in the 3 indicators among different age groups and trimesters in pregnant women were studied. Finally, reference intervals were established by nonparametric methods according to the recommendation of Clinical and Laboratory Standards Institute guideline C28-A3.

RESULTS

Compared with nonpregnant women, pregnant women had a significantly lower level of serum urea, creatinine, and UA (all P <.01), and no significant age-related differences in the 3 indicators were observed among the pregnant women (P >.05). However, the levels of these indicators were significantly different among the 3 trimesters (all P <.01 or P =.01). Accordingly, trimester-specific reference intervals of serum urea (1.6-4.4 mmol/L; 1.6-4.2 mmol/L; 1.6-4.4 mmol/L), creatinine (36-68 μmol/L; 34-66 μmol/L; 36-68 μmol/L), and UA (122-297 μmol/L; 129-327 μmol/L; 147-376 μmol/L) for trimesters 1, 2, and 3, respectively, were established.

CONCLUSION

These newly established reference intervals will be valuable for the detection and monitoring of kidney disease in pregnancy.

Kidney Imaging and Biopsy in Pregnancy

Physiologic glomerular, tubular, and structural changes related to pregnancy may complicate the detection of underlying kidney disease in pregnant patients. Imaging studies may provide important clinical information to assist in the diagnosis and treatment of kidney disease during pregnancy. Furthermore, in select patients who develop new or worsening kidney disease in pregnancy, kidney biopsy may be essential to ensure the accuracy of diagnosis and guide treatment choices. This review article will discuss the risks and benefits of various modalities used to image the kidneys and urinary tract during pregnancy to aid in the judicious selection of appropriate imaging studies that are likely to maximize clinical benefit while minimizing fetal risk. It will also highlight the potential benefits and harms associated with antepartum kidney biopsy and will offer strategies for identifying patients who are most likely to benefit from kidney biopsy during pregnancy.

Role of sFlt-1/PIGF ratio and uterine Doppler in pregnancies with chronic kidney disease suspected with Pre-eclampsia or HELLP syndrome

PURPOSE

Pregnancies of women with chronic kidney disease (CKD) are at higher risk of experiencing adverse perinatal (APO) and maternal outcome (AMO). Mean uterine artery pulsatility index (mUtA-PI) as well as the ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) are helpful tools in diagnosing pre-eclampsia (PE) in women with CKD. The aim of the study was to evaluate the role of sFlt-1/PIGF ratio and mUtA-PI as predictors for APO, AMO, preterm delivery and decline of kidney function in CKD pregnancies.

METHODS

A total of 28 CKD pregnancies with suspected PE/HELLP syndrome were retrospectively included, in whom both sFlt-1/PIGF and mUtA-PI were determined during the third trimester. APO was defined as fetal growth restriction, respiratory distress syndrome, intubation, admission to NICU, 5 min Apgar <7 and intracerebral hemorrhage. AMO was defined as the development of PE, HELLP syndrome or resistant hypertension. Decline of kidney function was defined as a 25% increase of creatinine level after delivery.

RESULTS

Of all included women, eight (28.6%) developed a PE/HELLP syndrome. AMO (28.6%) and APO (32.1%) were frequently observed. ROC analyses revealed a predictive value for AMO and sFlt-1/PIGF or mUtA-PI. Neither sFlt-1/PIGF nor mUtA-PI could predict APO or decline of postnatal kidney function. mUtA-PI was a predictor for preterm delivery.

CONCLUSION

Uterine Doppler and sFlt-1/PIGF are predictors of AMO in CKD pregnancies. Therefore, both markers might be helpful for an improved risk assessment. However, neither sFlt-1/PIGF nor mUtA-PI were able to predict a decline of postnatal kidney function or APO.

Estimating the glomerular filtration rate in pregnancy: The evaluation of the Nanra and CKD-EPI serum creatinine-based equations

Aim

To compare the performance of the Nanra and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for estimating glomerular filtration rate in pregnancy against the 24 h urine creatinine clearance.

Methods

Pregnant women had 24 h urine collections with simultaneous serum creatinine levels. Measured 24 h urine creatinine clearance was compared to two equations: Nanra and CKD-EPI. Level of concordance was measured, with an a priori bias acceptance of ±15 ml/min/1.73 m².

Results

A total of 53 synchronous urine and serum creatinine samples were analysed. The Nanra equation had a bias of -13.4 ml/min/1.73 m² while the CKD-EPI equation had bias of 14.2 ml/min/1.73 m². Both equations showed a high degree of proportional error and had poor agreement with 24 h urine creatinine clearance.

Conclusions

None of the equations were shown to reliably measure the estimated glomerular filtration rate in pregnant women. A valid serum creatinine-based estimated glomerular filtration rate equation in pregnancy is yet to be established.

Pregnancy-Related Acute Kidney Injury in Preeclampsia: Risk Factors and Renal Outcomes

Preeclampsia is a common cause of acute kidney injury (AKI) in low- and middle-income countries, but AKI incidence in preeclampsia, its risk factors, and renal outcomes are unknown. A prospective observational multicenter study of women admitted with preeclampsia in South Africa was conducted. Creatinine concentrations were extracted from national laboratory databases for women with maximum creatinine of ≥90 μmol/L (≥1.02 mg/dL). Renal injury and recovery were defined by Kidney Disease Improving Global Outcomes creatinine criteria. Predefined risk factors, maternal outcomes, and neonatal outcomes were compared between AKI stages. Of 1547 women admitted with preeclampsia 237 (15.3%) met AKI criteria: 6.9% (n=107) stage 1, 4.3% (n=67) stage 2, and 4.1% (n=63) stage 3. There was a higher risk of maternal death (n=7; relative risk, 4.3; 95% CI, 1.6-11.4) and stillbirth (n=80; relative risk, 2.2; 95% CI, 1.8-2.8) in women with AKI compared with those without. Perinatal mortality was also increased (89 of 240; 37.1%). Hypertension in a previous pregnancy was the strongest predictor of AKI stage 2 or 3 (odds ratio, 2.24; 95% CI, 1.21-4.17). Renal recovery rate reduced with increasing AKI stage. A third of surviving women (76 of 230 [33.0%]) had not recovered baseline renal function by discharge. Approximately half (39 of 76; 51.3%) of these women had no further creatinine testing post-discharge. In summary, AKI was common in women with preeclampsia and had high rates of associated maternal and perinatal mortality. Only two-thirds of women had confirmed renal recovery. History of a previous hypertensive pregnancy was an important risk factor.

Maternal kidney function during pregnancy: systematic review and meta-analysis

OBJECTIVES

To review systematically current literature on kidney function changes during pregnancy, in order to estimate the extent of adaptation over the course of both healthy physiological and complicated singleton pregnancies, and to determine healthy pregnancy reference values.

METHODS

PubMed (NCBI) and EMBASE (Ovid) electronic databases were searched, from inception to July 2017, for studies on kidney function during uncomplicated and complicated pregnancies. Included studies were required to report a non-pregnant reference value of kidney function (either in a non-pregnant control group or as a prepregnancy or postpartum measurement) and a pregnancy measurement at a predetermined and reported gestational age. Kidney function measures assessed were glomerular filtration rate (GFR) measured by inulin clearance, GFR measured by creatinine clearance and serum creatinine level. Pooled mean differences between pregnancy measurements and reference values were calculated for predefined intervals of gestational age in uncomplicated and complicated pregnancies using a random-effects model described by DerSimonian and Laird.

RESULTS

Twenty-nine studies met the inclusion criteria and were included in the analysis. As early as the first trimester, GFR was increased by up to 40-50% in physiological pregnancy when compared with non-pregnant values. Inulin clearance in uncomplicated pregnancy was highest at 36-41 weeks, with a 55.6% (53.7; 95% CI, 44.7-62.6 mL/min) increase when compared with non-pregnant values, and creatinine clearance was highest at 15-21 weeks' gestation, with a 37.6% (36.6; 95% CI, 26.2-46.9 mL/min) increase. Decrease in serum creatinine level in uncomplicated pregnancy was most prominent at 15-21 weeks, with a 23.2% (-0.19; 95% CI, -0.23 to -0.15 mg/dL) decrease when compared with non-pregnant values. Eight studies reported on pregnancies complicated by a hypertensive disorder. Meta-regression analysis showed a significant difference in all kidney function parameters when comparing uncomplicated and hypertensive complicated pregnancies.

CONCLUSIONS

In healthy pregnancy, GFR is increased as early as the first trimester, as compared with non-pregnant values, and the kidneys continue to function at a higher rate throughout gestation. In contrast, kidney function is decreased in hypertensive pregnancy. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

The Association Between GFR Evaluated by Serum Cystatin C and Proteinuria During Pregnancy

Introduction

Physiological changes in pregnancy result in increased cardiac output and renal blood flow, with a consequential increase in proteinuria. Data from studies of the relationship between proteinuria caused by isolated proteinuria and glomerular filtration rate (GFR) are still limited. The objective of this study was to investigate the effects of isolated proteinuria on the cystatin C–based GFR in the third trimester of pregnancy.

Methods

Data were collected from pregnant women in their third trimester whose serum creatinine levels were normal. The GFR of each participant was measured using serum cystatin C levels, and proteinuria was measured using urine protein–creatinine ratios. The participants were divided into 3 groups according to their level of proteinuria: normal (<150 mg/d), physiological (150–300 mg/d), and gestational (>300 mg/d). Changes in GFR were recorded for each group.

Results

The study included 89 participants, of whom 66.3% had levels of proteinuria that did not differ from that of the normal population (<150 mg/d). The incidence of physiological and gestational proteinuria was 21.4% and 12.4%, respectively. The results demonstrate that proteinuria >101.50 mg/d was significantly associated with declined estimated glomerular filtration rate (eGFR) (r = –0.34, P = 0.01). The analysis found that proteinuria >491.27 mg/d led to a risk of GFR <90 ml/min with an odds ratio of 12.69, P = 0.02 when adjusted for systolic blood pressure (SBP), diastolic blood pressure (DBP), and body mass index.

Conclusion

This study suggests that the term “physiological proteinuria” is a misnomer. When used in the traditional manner, creatinine level has inadequate sensitivity to estimate GFR in pregnant women. We found that there is a significant decline in GFR when urine protein > 101.5 mg/d, which could be an early biomarker for renal pathology rather than pregnancy physiology, suggesting that further workup and precaution is required.

Postpartum care of women with renal disease

Twenty-three percent of women with known chronic kidney disease (CKD) have been reported to demonstrate the first decline in kidney function between giving birth and six-weeks postpartum. As such, these women warrant close monitoring during the postpartum period irrespective of their pregnancy journey. Substantial haemodynamic variability during pregnancy and postpartum renders estimated glomerular filtration rate inaccurate, and poorly defined normal ranges of markers of kidney function at this time pose challenges for accurate assessment of renal complications. Multi-disciplinary specialist care is therefore essential, with consideration of specific implications of any known renal diagnosis and with observation for the development of postpartum complications of pregnancy. Furthermore, the postpartum period affords time to further investigate and diagnose kidney disease revealed by pregnancy. Good care planning and communication in the postpartum period has the potential to improve long-term health outcomes for women with known or new CKD and will be discussed in this review.

Serum Creatinine Levels Before, During, and After Pregnancy

This study uses Canadian administrative health databases to estimate gestational age–specific serum creatinine levels before, during, and after pregnancy among women without antecedent kidney disease.

Cystatin C as a novel predictor of preterm labor in severe preeclampsia

Background

The most common cause of acute kidney injury (AKI) in pregnancy is preeclampsia. Serum cystatin C (CysC) is a potential biomarker of early kidney damage as its levels are not disturbed by volume status changes in pregnancy, and serum CysC levels could serve as a replacement for conventionally used creatinine. In this study, we investigated the serum levels of CysC in severe preeclampsia cases and the associations between CysC levels and poor obstetric outcomes.

Methods

Our cohort included severe preeclampsia patients with a normal serum creatinine level. Creatinine was measured to calculate estimated glomerular filtration rate (eGFR) based on the Cockcroft and Gault, Modification of Diet in Renal Disease Study (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, while CysC was measured to calculated eGFR based on a CysC-based equation. We then evaluated the correlations between serum CysC level, eGFR, and obstetric outcomes.

Results

Twenty-six patients were evaluated of which 38.5% delivered preterm and 30.8% had low-birth weight babies. Unlike creatinine-based eGFR and CysC-based eGFR, serum CysC demonstrate significant negative correlation with gestational age. Receiver operating characteristic curve analysis indicated that serum CysC is a potential biomarker of preterm delivery with a cut-off serum level of 1.48 mg/L with 80% sensitivity and 75% specificity.

Conclusion

GFR estimation using CysC is likely to be inaccurate in pregnancy. However, we found a significant correlation between preterm delivery and serum CysC level. Our results suggest that serum CysC level has the potential to predict preterm delivery in severe preeclampsia patients.

Acute kidney injury in pregnancy including renal disease diagnosed in pregnancy

Pregnancy-related acute kidney injury (AKI) is a rare but serious complication in high-income settings and remains an important cause of maternal and foetal morbidity and mortality in low- and middle-income settings. Hypertensive disorders of pregnancy are the leading cause of pregnancy-related AKI worldwide. In this article, we outline the epidemiology, aetiology, recognition, investigation and management of pregnancy-related AKI. Difficulties in the definition of AKI, approaches to determine the cause of AKI in diagnostically challenging circumstances and diagnosis of new renal disease in pregnancy are discussed.

Serum Creatinine in Pregnancy: A Systematic Review

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

A best-practice position statement on pregnancy after kidney transplantation: focusing on the unsolved questions. The Kidney and Pregnancy Study Group of the Italian Society of Nephrology

Kidney transplantation (KT) is often considered to be the method best able to restore fertility in a woman with chronic kidney disease (CKD). However, pregnancies in KT are not devoid of risks (in particular prematurity, small for gestational age babies, and the hypertensive disorders of pregnancy). An ideal profile of the potential KT mother includes “normal” or “good” kidney function (usually defined as glomerular filtration rate, GFR ≥ 60 ml/min), scant or no proteinuria (usually defined as below 500 mg/dl), normal or well controlled blood pressure (one drug only and no sign of end-organ damage), no recent acute rejection, good compliance and low-dose immunosuppression, without the use of potentially teratogen drugs (mycophenolic acid and m-Tor inhibitors) and an interval of at least 1–2 years after transplantation. In this setting, there is little if any risk of worsening of the kidney function. Less is known about how to manage “non-ideal” situations, such as a pregnancy a short time after KT, or one in the context of hypertension or a failing kidney. The aim of this position statement by the Kidney and Pregnancy Group of the Italian Society of Nephrology is to review the literature and discuss what is known about the clinical management of CKD after KT, with particular attention to women who start a pregnancy in non-ideal conditions. While the experience in such cases is limited, the risks of worsening the renal function are probably higher in cases with markedly reduced kidney function, and in the presence of proteinuria. Well-controlled hypertension alone seems less relevant for outcomes, even if its effect is probably multiplicative if combined with low GFR and proteinuria. As in other settings of kidney disease, superimposed preeclampsia (PE) is differently defined and this impairs calculating its real incidence. No specific difference between non-teratogen immunosuppressive drugs has been shown, but calcineurin inhibitors have been associated with foetal growth restriction and low birth weight. The clinical choices in cases at high risk for malformations or kidney function impairment (pregnancies under mycophenolic acid or with severe kidney-function impairment) require merging clinical and ethical approaches in which, beside the mother and child dyad, the grafted kidney is a crucial “third element”.

Gestation-Specific Changes in the Anatomy and Physiology of Healthy Pregnant Women: An Extended Repository of Model Parameters for Physiologically Based Pharmacokinetic Modeling in Pregnancy

BACKGROUND

In the past years, several repositories for anatomical and physiological parameters required for physiologically based pharmacokinetic modeling in pregnant women have been published. While providing a good basis, some important aspects can be further detailed. For example, they did not account for the variability associated with parameters or were lacking key parameters necessary for developing more detailed mechanistic pregnancy physiologically based pharmacokinetic models, such as the composition of pregnancy-specific tissues.

OBJECTIVES

The aim of this meta-analysis was to provide an updated and extended database of anatomical and physiological parameters in healthy pregnant women that also accounts for changes in the variability of a parameter throughout gestation and for the composition of pregnancy-specific tissues.

METHODS

A systematic literature search was carried out to collect study data on pregnancy-related changes of anatomical and physiological parameters. For each parameter, a set of mathematical functions was fitted to the data and to the standard deviation observed among the data. The best performing functions were selected based on numerical and visual diagnostics as well as based on physiological plausibility.

RESULTS

The literature search yielded 473 studies, 302 of which met the criteria to be further analyzed and compiled in a database. In total, the database encompassed 7729 data. Although the availability of quantitative data for some parameters remained limited, mathematical functions could be generated for many important parameters. Gaps were filled based on qualitative knowledge and based on physiologically plausible assumptions.

CONCLUSION

The presented results facilitate the integration of pregnancy-dependent changes in anatomy and physiology into mechanistic population physiologically based pharmacokinetic models. Such models can ultimately provide a valuable tool to investigate the pharmacokinetics during pregnancy in silico and support informed decision making regarding optimal dosing regimens in this vulnerable special population.

Fetal Risks and Maternal Renal Complications in Pregnancy with Preexisting Chronic Glomerulonephritis

BACKGROUND Analysis the maternal and fetal risk predictors in pregnancy in conjunction with chronic glomerulonephritis (CGN) patients are helpful to understand the influence of kidney diseases on pregnancy and the effects of pregnancy on kidney diseases. The aim of this study was to determine the predictors of adverse maternal and fetal outcomes in CGN patients. MATERIAL AND METHODS Maternal and fetal outcomes in 64 pregnancies of CGN patients were retrospectively analyzed. We randomly selected 100 low-risk-pregnancy women without chronic kidney disease (CKD) at the same time as the control group. Clinical manifestations, laboratory data, medication, and outcomes during pregnancies of these patients were analyzed by univariate and logistic regression. RESULTS CGN patients were associated with higher adverse pregnancy outcomes versus general pregnancies. The gestational ages are shorter, and the incidence of preeclampsia, gestational hypertension, and abortion were increased. The rates of premature delivery, low birth weights, and intrauterine growth restriction were higher in the CGN group. Prenatal proteinuria and blood pressure were significantly increased compared with pre-pregnancy stage. Proteinuria (0.9±0.6 g/d vs. 0.5±0.3 g/d, P=0.032) and hypertension (6.9% vs. 3.4%, P=0.021) at 6 months after delivery were aggravated. Prenatal proteinuria ≥3.5 g/d (OR 12.22, 95%CI 3.16~47.32, P=0.001) was the maternal risk predictor in pregnancy. Prenatal blood pressure ≥160/110 mmHg (OR 8.97, 95%CI 1.69~47.53, P=0.010) and uric acid ≥363 μmol/L (OR 7.35, 95%CI 1.88~28.76, P=0.004) were the fetal risk predictors in pregnancy in conjunction with CGN patients. CONCLUSIONS Maternal-fetal risks are increased in pregnancies in conjunction with CGN patients. Prenatal proteinuria ≥3.5 g/d, BP ≥160/110 mmHg, and uric acid ≥363 μmol/L were the maternal and fetal risk predictors in pregnancy.

A Multicenter Cohort Study of Histologic Findings and Long-Term Outcomes of Kidney Disease in Women Who Have Been Pregnant

BACKGROUND AND OBJECTIVES

For many women pregnancy is the first contact with health services, thus providing an opportunity to identify renal disease. This study compares causes and long-term renal outcomes of biopsy-proven renal disease identified during pregnancy or within 1 year postpartum, with nonpregnant women.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Native renal biopsies (1997-2012), in women of childbearing age (16 to <50 years), from 21 hospitals were studied. The pregnancy-related diagnosis group included those women with abnormal urinalysis/raised creatinine identified during pregnancy or within 1 year postpartum. Pregnancy-related and control biopsies were matched for age and ethnicity (black versus nonblack).

RESULTS

One hundred and seventy-three pregnancy-related biopsies (19 antenatal, 154 postpregnancy) were identified and matched with 1000 controls. FSGS was more common in pregnancy-related biopsies (32.4%) than controls (9.7%) (P<0.001) but there were no differences in Columbia classification. Women with a pregnancy-related diagnosis were younger (32.1 versus 34.2 years; P=0.004) and more likely to be black (26.0% versus 13.3%; P<0.001) than controls, although there were no differences in ethnicities in women with FSGS. The pregnancy-related group (excluding antenatal biopsies) was more likely to have a decline in Chronic Kidney Disease Epidemiology Collaboration eGFR in the follow-up period than the control group (odds ratio, 1.67; 95% confidence interval, 1.03 to 2.71; P=0.04), and this decline appeared to be more rapid (-1.33 versus -0.56 ml/min per 1.73 m2 per year, respectively; P=0.045). However, there were no differences between groups in those who required RRT or who died.

CONCLUSIONS

Pregnancy is an opportunity to detect kidney disease. FSGS is more common in women who have been pregnant than in controls, and disease identified in pregnancy or within 1 year postpartum is more likely to show a subsequent decline in renal function. Further work is required to determine whether pregnancy initiates, exacerbates, or reveals renal disease.

Pregnancy in chronic kidney disease and kidney transplantation

Chronic kidney disease (CKD) affects up to 6% of women of childbearing age in high income countries, and is estimated to affect 3% of pregnant women. Advanced renal dysfunction, proteinuria, hypertension, and poorly controlled underlying primary renal disease are all significant risks for adverse maternal, fetal, and renal outcomes. In order to achieve the best outcomes, it is therefore of paramount importance that these pregnancies are planned, where possible, to allow the opportunity to counsel women and their partners in advance and to optimize these risks. These pregnancies should be deemed high risk and they require close antenatal monitoring from an expert multidisciplinary team. We discuss the effect of pregnancy on CKD, and also current guidelines and literature with specific reference to transplantation, autoimmune disease, and medication use in pregnancy. We also discuss the benefits of prepregnancy counseling and give practical recommendations to advise pregnant women with renal disease.

Trauma and Considerations Unique to Pregnancy

Trauma complicates 6% to 7% of all pregnancies and requires multidisciplinary education and training for both trauma and obstetric teams to achieve the best outcome. It is important to understand the mechanisms of certain adverse maternal and fetal/neonatal outcomes incurred as a result of trauma, as well as caveats to pregnancy physiology that make some injuries more likely and detection of maternal compromise more difficult. This article focuses on these caveats and how to incorporate these into ongoing trauma protocols and offers suggestions for the formation of obstetric trauma response team.

Pregnancy and Lupus Nephritis

The management of lupus nephritis in pregnancy presents a diagnostic and therapeutic challenge for providers. Pregnancy creates a series of physiologic changes in the immune system and kidney that may result in an increased risk of disease flare and adverse maternal and fetal outcomes, such as preeclampsia, fetal loss, and preterm delivery. Conception should be delayed until disease is in remission to ensure the best pregnancy outcomes. Maternal disease activity and fetal well-being should be monitored closely by an interdisciplinary team, including obstetricians, rheumatologists, and nephrologists throughout pregnancy. Careful attention must be paid to the dosing and potential teratogenicity of medications.

A best practice position statement on pregnancy in chronic kidney disease: the Italian Study Group on Kidney and Pregnancy

Pregnancy is increasingly undertaken in patients with chronic kidney disease (CKD) and, conversely, CKD is increasingly diagnosed in pregnancy: up to 3 % of pregnancies are estimated to be complicated by CKD. The heterogeneity of CKD (accounting for stage, hypertension and proteinuria) and the rarity of several kidney diseases make risk assessment difficult and therapeutic strategies are often based upon scattered experiences and small series. In this setting, the aim of this position statement of the Kidney and Pregnancy Study Group of the Italian Society of Nephrology is to review the literature, and discuss the experience in the clinical management of CKD in pregnancy. CKD is associated with an increased risk for adverse pregnancy-related outcomes since its early stage, also in the absence of hypertension and proteinuria, thus supporting the need for a multidisciplinary follow-up in all CKD patients. CKD stage, hypertension and proteinuria are interrelated, but they are also independent risk factors for adverse pregnancy-related outcomes. Among the different kidney diseases, patients with glomerulonephritis and immunologic diseases are at higher risk of developing or increasing proteinuria and hypertension, a picture often difficult to differentiate from preeclampsia. The risk is higher in active immunologic diseases, and in those cases that are detected or flare up during pregnancy. Referral to tertiary care centres for multidisciplinary follow-up and tailored approaches are warranted. The risk of maternal death is, almost exclusively, reported in systemic lupus erythematosus and vasculitis, which share with diabetic nephropathy an increased risk for perinatal death of the babies. Conversely, patients with kidney malformation, autosomal-dominant polycystic kidney disease, stone disease, and previous upper urinary tract infections are at higher risk for urinary tract infections, in turn associated with prematurity. No risk for malformations other than those related to familiar urinary tract malformations is reported in CKD patients, with the possible exception of diabetic nephropathy. Risks of worsening of the renal function are differently reported, but are higher in advanced CKD. Strict follow-up is needed, also to identify the best balance between maternal and foetal risks. The need for further multicentre studies is underlined.

Risk of Adverse Pregnancy Outcomes in Women with CKD

CKD is increasingly prevalent in pregnancy. In the Torino-Cagliari Observational Study (TOCOS), we assessed whether the risk for adverse pregnancy outcomes is associated with CKD by comparing pregnancy outcomes of 504 pregnancies in women with CKD to outcomes of 836 low-risk pregnancies in women without CKD. The presence of hypertension, proteinuria (>1 g/d), systemic disease, and CKD stage (at referral) were assessed at baseline. The following outcomes were studied: cesarean section, preterm delivery, and early preterm delivery; small for gestational age (SGA); need for neonatal intensive care unit (NICU); new onset of hypertension; new onset/doubling of proteinuria; CKD stage shift; "general" combined outcome (preterm delivery, NICU, SGA); and "severe" combined outcome (early preterm delivery, NICU, SGA). The risk for adverse outcomes increased across stages (for stage 1 versus stages 4-5: "general" combined outcome, 34.1% versus 90.0%; "severe" combined outcome, 21.4% versus 80.0%; P<0.001). In women with stage 1 CKD, preterm delivery was associated with baseline hypertension (odds ratio [OR], 3.42; 95% confidence interval [95% CI], 1.87 to 6.21), systemic disease (OR, 3.13; 95% CI, 1.51 to 6.50), and proteinuria (OR, 3.69; 95% CI, 1.63 to 8.36). However, stage 1 CKD remained associated with adverse pregnancy outcomes (general combined outcome) in women without baseline hypertension, proteinuria, or systemic disease (OR, 1.88; 95% CI, 1.27 to 2.79). The risk of intrauterine death did not differ between patients and controls. Findings from this prospective study suggest a "baseline risk" for adverse pregnancy-related outcomes linked to CKD.

First-trimester combined screening for trisomy 21 in women with renal disease

OBJECTIVE

To evaluate the results of first-trimester combined screening for Down syndrome in women with chronic renal disease.

METHOD

Fifty-five pregnant women with renal disease were compared with 110 patients matched for maternal age, maternal weight, smoking status, and gestational age. Maternal renal function was assayed at the time of the combined screening, and renal insufficiency was defined by serum creatinine >90 µmol/L and renal clearance <80 mL/min. We defined three groups: kidney disease and normal renal function (group 1), kidney disease and renal insufficiency (group 2), and a control group (group 3). The values of nuchal translucency, pregnancy-associated plasma protein A, human β-chorionic gonadotrophin (hCGβ), and false-positive rates for Down syndrome screening were compared.

RESULTS

There were 39 (71%) and 16 (29%) cases in groups 1 and 2, respectively. Nuchal translucency and multiple of the median (MoM) pregnancy-associated plasma protein A were similar in the three groups. However, MoM hCGβ levels were higher in group 2 than in groups 1 and 3 (5.37 vs 1.1 vs 0.98 MoM, p = 0.0001). The resulting screen-positive rate was also higher in group 2 than in groups 1 and 3 (43.7% vs 10.2% vs 5.5%, p = 0.0001).

CONCLUSION

Trisomy 21 first-trimester screening using hCGβ is not suitable in the case of maternal renal failure. © 2014 John Wiley & Sons, Ltd.

Preeclampsia from a renal point of view: Insides into disease models, biomarkers and therapy

Proteinuria is a frequently detected symptom, found in 20% of pregnancies. A common reason for proteinuria in pregnancy is preeclampsia. To diagnose preeclampsia clinically and to get new insights into the pathophysiology of the disease it is at first essential to be familiar with conditions in normal pregnancy. Animal models and biomarkers can help to learn more about disease conditions and to find new treatment strategies. In this article we review the changes in kidney function during normal pregnancy and the differential diagnosis of proteinuria in pregnancy. We summarize different pathophysiological theories of preeclampsia with a special focus on the renal facets of the disease. We describe the current animal models and give a broad overview of different biomarkers that were reported to predict preeclampsia or have a prognostic value in preeclampsia cases. We end with a summary of treatment options for preeclampsia related symptoms including the use of plasmapheresis as a rescue therapy for so far refractory preeclampsia. Most of these novel biomarkers for preeclampsia are not yet implemented in clinical use. Therefore, we recommend using proteinuria (measured by UPC ratio) as a screening parameter for preeclampsia. Delivery is the only curative treatment for preeclampsia. In early preeclampsia the primary therapy goal is to prolong pregnancy until a state were the child has an acceptable chance of survival after delivery.

Successful outcome of pregnancy in patients with anti-neutrophil cytoplasm antibody-associated small vessel vasculitis

Pregnancy in patients with anti-neutrophil cytoplasm antibody-associated vasculitis is reportedly associated with a high risk of fetal and maternal complications. Here we describe the outcome of pregnancies in patients with granulomatosis with polyangiitis and microscopic polyangiitis at five centers in the United Kingdom using a retrospective case review of all women who became pregnant following diagnosis. We report 15 pregnancies in 13 women resulting in 15 live births including one twin pregnancy and 13 singleton pregnancies. One patient had an unplanned pregnancy and a first trimester miscarriage while taking methotrexate. All other pregnancies were planned following a minimum of 6 months clinical remission. Eleven successful pregnancies were delivered vaginally at full term, whereas three were delivered by cesarean section. All infants were healthy with no neonatal complications on their initial health check within the first 24 h of delivery and no evidence of neonatal vasculitis. One relapse occurred during pregnancy and was successfully treated with an increased dose of azathioprine and corticosteroids, intravenous immunoglobulin, and plasma exchange therapy. One patient developed tracheal crusting and subglottic stenosis of infective etiology in the third trimester requiring tracheal debridement post delivery. No patient had a relapse in the first 12 months postpartum. Thus, successful pregnancy outcomes can occur following planned pregnancy in women in sustained remission on non-teratogenic therapies.

Maternal glomerular filtration rate in pregnancy and fetal size

Background

The relationship of maternal glomerular filtration rate (GFR) in pregnancy to fetal size needs to be better characterized as it impacts an ongoing debate about confounding effect of maternal GFR in investigations of important environmental contaminants. We aimed to characterize the size of the association between maternal GFR and infant birth weight.

Materials and Methods

A sub-cohort of 953 selected women (470 women with and 483 women without preeclampsia) in the Norwegian Mother and Child Cohort (MoBa), recruited during 2003–2007 were analyzed. GFR in the second trimester was estimated based on plasma creatinine. Birth weight was ascertained from the Medical Birth Registry of Norway. Multivariate linear regression was used to evaluate the association between maternal GFR in second trimester (estimated by the Cockroft-Gault [GFR-CG] and the modification of diet in renal disease [GFR-MDRD] formulas) and infant birth weight. Partial correlation coefficients were also calculated.

Results

Maternal GFR-CG (β: 0.73 g/ml/min, p = 0.04) and GFR-MDRD (β: 0.83 g/ml/min, p = 0.04) were associated with infant birth weight in models adjusted for maternal weight in kilograms, preeclampsia, and gestational age at delivery (days). Partial correlation coefficients for the association between infant birth weight and GFR were 0.07 for both formulas. Although the birth weight-GFR association was stronger among the women with preeclampsia, the difference from women without preeclampsia was not statistically significant.

Conclusion

These data support an association between GFR during pregnancy and infant birth weight, and indicate that GFR may confound selected epidemiologic associations.

Impaired decline in renal threshold for glucose during pregnancy - a possible novel mechanism for gestational diabetes mellitus

BACKGROUND

The renal threshold for glucose (RT(G)) is determined by the nephron's reabsorptive capacity. Glucose is reabsorbed through sodium-coupled glucose cotransporters in the proximal tubules. During pregnancy, renal glucose reabsorptive capacity decreases, possibly, due to reduced glucose transporter expression. Our hypothesis is that inadequate decrease in RT(G) during pregnancy will make women more prone to develop gestational diabetes mellitus (GDM).

METHODS

Pregnant women (n = 40) who were referred to our center for oral glucose tolerance test (OGTT) were included in the analysis. Plasma glucose levels and urinary glucose excretion were measured for 4 h after 100 g oral glucose load. These data were used to calculate RT(G) . The subjects were divided into two cohorts, GDM and non-GDM, according to the OGTT results. Mean RT(G) was compared between the two groups.

RESULTS

Fifteen (37.5%) of the women were diagnosed with GDM. Seventeen participants had only trace amounts of urinary glucose excretion, and no value of RT(G) could be determined; RT(G) was determined in the other 23 subjects. Among these 23 women, 13 were diagnosed as GDM, and 10 had normal OGTT. RT(G) was lower in the non-GDM women (146 ± 14 mg/dL) than in the GDM women (182 ± 18 mg/dL), p < 0.001.

CONCLUSIONS

Gestational diabetes mellitus is associated with higher RT(G) during pregnancy compared with non-GDM. These results support our hypothesis that inadequate decrease of the RT(G) may have a pathophysiological role in the development of GDM.