Glomerular filtration during and after pregnancy

Twenty-four-hour urinary protein excretion in uncomplicated singleton pregnancy

BACKGROUND

Twenty-four-hour urinary total protein excretion is an essential parameter used for evaluation of renal function and early detection of gestational complications. However, data on reference ranges of 24-hour urinary total protein excretion in normal pregnancy are scarce.

OBJECTIVE

This study aimed to determine reference ranges for 24-hour urinary total protein excretion in a population with uncomplicated singleton pregnancies using a standard method for urinary total protein. In addition, the values of 24-hour urinary total protein were stratified by maternal age and prepregnancy body mass index.

STUDY DESIGN

This study was based on a prospective cohort study in Shenzhen, China. The pregnant women were enrolled at their first prenatal clinical visit. All the participants were instructed to collect 24-hour urine samples during the following successive gestational periods: 6+0 to 13+6, 14+0 to 27+6, and 28+0 to 41+6 weeks. Total urinary protein excretion was analyzed by a colorimetric method. Ultimately, the study encompassed a total of 4844 pregnant women with uncomplicated pregnancies. The nonparametric percentile method was used to determine reference ranges for 24-hour urinary total protein excretion during different trimesters in women with uncomplicated pregnancies (excluding those with previous kidney disorders, gestational or chronic hypertension, preeclampsia, and pregestational diabetes mellitus, among others).

RESULTS

The 24-hour urinary total protein levels expressed as medians and percentiles (5th, 95th) for each trimester were as follows: 72.0 (28.4, 165.0), 88.0 (34.0, 185.0), and 108.0 (37.5, 258.0) mg in the first, second, and third trimesters, respectively. A significant increase in 24-hour urinary total protein excretion was observed throughout pregnancy (all P values <.001). Moreover, 24-hour urinary total protein levels were higher in the older (≥35 years) than in the younger (<35 years) group from mid-gestation. Specifically, the median (interquartile range) 24-hour urinary total protein levels by age were 72.2 (50.6-100.0) vs 70.5 (50.5-100.0) mg, 85.8 (62.0-117.0) vs 96.0 (68.0-127.8) mg, and 106.6 (76.0-146.2) vs 114.7 (81.5-153.6) mg in the first, second, and third trimesters, respectively. In addition, 24-hour proteinuria was significantly increased in higher-weight (overweight or obese) subgroups compared with lower-weight (underweight or normal-weight) subgroups (all P values <.05).

CONCLUSION

Our study provides reference values for 24-hour urinary total protein excretion with apparently uncomplicated pregnancies. Understanding these changes in low-risk pregnancies is essential for optimizing maternal management.

Proteinuria during pregnancy: definition, pathophysiology, methodology, and clinical significance

Qualitative and quantitative measurement of urine protein excretion is one of the most common tests performed during pregnancy. For more than 100 years, proteinuria was necessary for the diagnosis of preeclampsia, but recent guidelines recommend that proteinuria is sufficient but not necessary for the diagnosis. Still, in clinical practice, most patients with gestational hypertension will be diagnosed as having preeclampsia based on the presence of proteinuria. Although the reference standard for measuring urinary protein excretion is a 24-hour urine collection, spot urine protein-to-creatinine ratio is a reasonable "rule-out" test for proteinuria. Urine dipstick screening for proteinuria does not provide any clinical benefit and should not be used to diagnose proteinuria. The classic cutoff cited to define proteinuria during pregnancy is a value of >300 mg/24 hours or a urine protein-to-creatinine ratio of at least 0.3. Using this cutoff, the rate of isolated proteinuria in pregnancy may reach 8%, whereas preeclampsia occurs among 3% to 8% of pregnancies. Although this threshold is widely accepted, its origin is not based on evidence on adverse pregnancy outcomes but rather on expert opinion and results of small studies. After reviewing the available data, the most important factor that influences maternal and neonatal outcome is the severity of blood pressures and presence of end organ damage, rather than the excess protein excretion. Because the management of gestational hypertension and preeclampsia without severe features is almost identical in frequency of surveillance and timing of delivery, the separation into 2 disorders is unnecessary. If the management of women with gestational hypertension with a positive assessment of proteinuria will not change, we believe that urine assessment for proteinuria is unnecessary in women who develop new-onset blood pressure at or after 20 weeks' gestation. Furthermore, we do not recommend repeated measurement of proteinuria for women with preeclampsia, the amount of proteinuria does not seem to be related to poor maternal and neonatal outcomes, and monitoring proteinuria may lead to unindicated preterm deliveries and related neonatal complications. Our current diagnosis of preeclampsia in women with chronic kidney disease may be based on a change in protein excretion, a baseline protein excretion evaluation is critical in certain conditions such as chronic hypertension, diabetes, and autoimmune or other renal disorders. The current definition of superimposed preeclampsia possesses a diagnostic dilemma, and it is unclear whether a change in the baseline proteinuria reflects another systemic disease such as preeclampsia or whether women with chronic disease such as chronic hypertension or diabetes will experience a different "normal" pattern of protein excretion during pregnancy. Finally, limited data are available regarding angiogenic and other biomarkers in women with chronic kidney disease as a potential aid in distinguishing the worsening of baseline chronic kidney disease and chronic hypertension from superimposed preeclampsia.

Changes of Plasma Analytes Reflecting Metabolic Adaptation to the Different Stages of the Lactation Cycle in Healthy Multiparous Holstein Dairy Cows Raised in High-Welfare Conditions

Simple Summary

This study investigates the changes occurring in plasma analytes of healthy multiparous Holstein dairy cows during the dry, the postpartum, the early and the late lactation phases. A welfare assessment at the herd level and a retrospective subclinical diseases screening were used as blocking factors for the selection of reference individuals. Thus, this study provides measurements of the physiological variations affecting plasma analytes concentrations during the pivotal stages of the lactation cycle in a healthy, high welfare-raised subset of reference individuals and suggest an explanation for the underlying processes involved. Finally, we propose reference intervals for plasma analytes in the stages investigated.

Abstract

Here, we tested the changes occurring in several plasma analytes during different stages of the lactation cycle of high welfare raised multiparous Holstein cows, and provided reference intervals (RI) for plasma analytes concentrations. Eleven high-welfare farms (HWF) located in Northern Italy were selected and their herds used to recruit 361 clinically healthy cows undergoing the dry (from −30 to −10 days from real calving; DFC), the postpartum (from 3 to 7 DFC), the early lactation (from 28 to 45 DFC) and the late lactation phases (from 160 to 305 DFC). Cows affected by subclinical diseases (SCD) were retrospectively excluded, and a subset of 285 cows was selected. Data of plasma analytes underwent ANOVA testing using physiological phases as predictors. The individual effect of each phase was assessed using a pairwise t-test assuming p ≤ 0.05 as a significance limit. A bootstrap approach was used to define the reference interval (RI) for each blood analyte within physiological phases having a pairwise t-test p ≤ 0.05. The concentration of nonesterified fatty acids, albumin, cholesterol, retinol, paraoxonase and tocopherol changed throughout all the physiological phases, whereas the concentration of K, alkaline phosphatase and thiol groups remained stable. Triglycerides, Zn, and ferric ion reducing antioxidant power in the dry phase and BHB, Ca, myeloperoxidase, haptoglobin, reactive oxygen metabolites and advanced oxidation of protein product in postpartum differed compared with other physiological phases. During the dry phase, Packed cell volume, Cl, and urea concentrations were similar to during the postpartum phase. Similarly, Na, γ-glutamyl transferase and β-carotene concentrations were similar to during the early lactation phase; fructosamine and bilirubin concentrations were similar to during the late lactation phase. During the postpartum phase, fructosamine and P concentrations were similar to during the early lactation phase, and the aspartate transaminase concentration was similar to during the late lactation phase. During the early lactation phase, Mg, creatinine, total protein, globulin and ceruloplasmin concentrations were similar to during the postpartum phase, while the urea concentration was similar to during the late lactation phase. All these plasma analytes differed among the other phases. This study identifies physiological trends affecting plasma analytes concentrations during the different stages of the lactation cycle and provides a guideline for the duration and magnitude of their changes when animals are healthy and raised in optimal welfare conditions.

Therapeutic Drug Monitoring in Pregnant Patients

During pregnancy, there are several physiological changes during each trimester that can affect the absorption, distribution, metabolism, and elimination of drugs. Although there is a potential need to understand the pharmacokinetics and pharmacodynamics of drugs in pregnant patients, therapeutic drug monitoring is not well established for various drug classes due to ethical and safety concerns regarding the neonate. Potential risks from in utero drug exposure to the fetus may impact growth and development and may cause malformations or teratogenesis. The clinician must consider the benefits of drug treatment for the pregnant mother versus the risk to the fetus, before prescribing medications during pregnancy. The objective of this review is to aid clinicians, pharmacists, and laboratorians in understanding the pharmacokinetic and pharmacodynamic changes during pregnancy, to provide drug class recommendations for monitoring therapy throughout pregnancy via therapeutic drug monitoring, and to highlight the recent directives of governing agencies on maternal and fetal health.

Psychotropic drug use in perinatal women with bipolar disorder

Optimal dose management of psychotropic drugs during the perinatal period reduces the risk for recurrence of mood episodes in women with Bipolar Disorder. Physiological changes during pregnancy are associated with decreases in the plasma concentrations of the majority of mood stabilizing medications. Regular symptom and drug concentration monitoring for lithium and anticonvulsants with reflexive dose adjustment improves the probability of sustained symptom remission across pregnancy. The elimination clearance trajectory across pregnancy for psychotropics dictates the frequency of laboratory monitoring and dose adjustment. The literature on the pharmacokinetics of lithium, lamotrigine, carbamazepine and atypical antipsychotics during pregnancy and postpartum are reviewed, recommendations for symptom and laboratory monitoring are proposed and recommendations for dose adjustments are presented.

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.

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.

Uterine artery leptin receptors during the ovarian cycle and pregnancy regulate angiogenesis in ovine uterine artery endothelial cells†

Leptin regulates body weight, reproductive functions, blood pressure, endothelial function, and fetoplacental angiogenesis. Compared to the luteal phase, the follicular phase and pregnancy are physiological states of elevated estrogen, angiogenesis, and uterine blood flow (UBF). Little is known concerning regulation of uterine artery (UA) angiogenesis by leptin and its receptors. We hypothesized that (1) ex vivo expression of leptin receptors (LEPR) in UA endothelium (UAendo) and UA vascular smooth muscle (UAvsm) is elevated in pregnant versus nonpregnant (Luteal and Follicular) sheep; (2) in vitro leptin treatments differentially modulate mitogenesis in uterine artery endothelial cells from pregnant (P-UAECs) more than in nonpregnant (NP-UAECs) ewes; and (3) LEPR are upregulated in P-UAECs versus NP-UAECs in association with leptin activation of phospho-STAT3 signaling. Local UA adaptations were evaluated using a unilateral pregnant sheep model where prebreeding uterine horn isolation (nongravid) restricted gravidity to one horn. Immunolocalization revealed LEPR in UAendo and UAvsm from pregnant and nonpregnant sheep. Contrary to our hypothesis, western analysis revealed that follicular UAendo and UAvsm LEPR were greater than luteal, nongravid, gravid, and control pregnant. Compared to pregnant groups, LEPR were elevated in renal artery endothelium of follicular and luteal sheep. Leptin treatment significantly increased mitogenesis in follicular phase NP-UAECs and P-UAECs, but not luteal phase NP-UAECs. Although UAEC expression of LEPR was similar between groups, leptin treatment only activated phospho-STAT3 in follicular NP-UAECs and P-UAECs. Thus, leptin may play an angiogenic role particularly in preparation for the increased UBF during the periovulatory period and subsequently to meet the demands of the growing fetus.

Mechanisms of Renal Vasodilation and Hyperfiltration During Pregnancy

Glomerular filtration rate (GFR) and renal plasma flow (RPF) increase by 40-65% and 50-85%, respectively, during normal pregnancy in women. Studies using the gravid rat as a model have greatly enhanced our understanding of mechanisms underlying these remarkable changes in the renal circulation during gestation. Hyperfiltration appears to be almost completely due to the increase in RPF, the latter attributable to profound reductions in both the renal afferent and efferent arteriolar resistances. The major pregnancy hormone involved is relaxin. The mediators downstream from relaxin include endothelin (ET) and nitric oxide (NO). New evidence indicates that relaxin increases vascular gelatinase activity during pregnancy, thereby converting big ET to ET(1-32), which leads to renal vasodilation, hyperfiltration, and reduced myogenic reactivity of small renal arteries via the endothelial ET(B) receptor and NO. Whether the chronic volume expansion characteristic of pregnancy contributes to the maintenance of gestational renal changes requires further investigation. Additional studies are also needed to further delineate the molecular basis of these mechanisms and, importantly, to investigate whether they apply to women.

Median Urinary Iodine Concentrations Are Indicative of Adequate Iodine Status among Women of Reproductive Age in Prey Veng, Cambodia

Iodine deficiency disorders are estimated to affect over 1.9 million people worldwide. Iodine deficiency is especially serious for women during pregnancy and lactation because of the negative consequences for both mother and infant. The aim of this cross-sectional study was to determine the median urinary iodine concentration (UIC) as a population-level indicator of iodine status among rural women farmers of reproductive age (18-45 years) in the province of Prey Veng, Cambodia. A total of 450 women provided a spot morning urine sample in 2012. Of those women, 93% (n = 420) were non-pregnant and 7% (n = 30) were pregnant at the time of collection. UIC was quantified using the Sandell-Kolthoff reaction with modifications. The median UIC of non-pregnant (139 μg/L) and pregnant women (157 μg/L) were indicative of adequate iodine status using the WHO/UNICEF/ICCIDD epidemiological criteria for both groups (median UIC between 100-199 and 150-249 μg/L, respectively). We conclude that non-pregnant and pregnant women in rural Prey Veng, Cambodia had adequate iodine status based on single spot morning urine samples collected in 2012. More research is warranted to investigate iodine status among larger and more representative populations of women in Cambodia, especially in light of recent policy changes to the national program for universal salt iodization.

Associations of Perfluoroalkyl Substances (PFAS) with Lower Birth Weight: An Evaluation of Potential Confounding by Glomerular Filtration Rate Using a Physiologically Based Pharmacokinetic Model (PBPK)

BACKGROUND

Prenatal exposure to perfluoroalkyl substances (PFAS) has been associated with lower birth weight in epidemiologic studies. This association could be attributable to glomerular filtration rate (GFR), which is related to PFAS concentration and birth weight.

OBJECTIVES

We used a physiologically based pharmacokinetic (PBPK) model of pregnancy to assess how much of the PFAS-birth weight association observed in epidemiologic studies might be attributable to GFR.

METHODS

We modified a PBPK model to reflect the association of GFR with birth weight (estimated from three studies of GFR and birth weight) and used it to simulate PFAS concentrations in maternal and cord plasma. The model was run 250,000 times, with variation in parameters, to simulate a population. Simulated data were analyzed to evaluate the association between PFAS levels and birth weight due to GFR. We compared simulated estimates with those from a meta-analysis of epidemiologic data.

RESULTS

The reduction in birth weight for each 1-ng/mL increase in simulated cord plasma for perfluorooctane sulfonate (PFOS) was 2.72 g (95% CI: -3.40, -2.04), and for perfluorooctanoic acid (PFOA) was 7.13 g (95% CI: -8.46, -5.80); results based on maternal plasma at term were similar. Results were sensitive to variations in PFAS level distributions and the strength of the GFR-birth weight association. In comparison, our meta-analysis of epidemiologic studies suggested that each 1-ng/mL increase in prenatal PFOS and PFOA levels was associated with 5.00 g (95% CI: -21.66, -7.78) and 14.72 g (95% CI: -8.92, -1.09) reductions in birth weight, respectively.

CONCLUSION

Results of our simulations suggest that a substantial proportion of the association between prenatal PFAS and birth weight may be attributable to confounding by GFR and that confounding by GFR may be more important in studies with sample collection later in pregnancy.

The Homozygous Hemoglobin EE Genotype and Chronic Inflammation Are Associated with High Serum Ferritin and Soluble Transferrin Receptor Concentrations among Women in Rural Cambodia

BACKGROUND

Ferritin and soluble transferrin receptor (sTfR) concentrations are commonly used to assess iron deficiency (ID); however, they are influenced by multiple factors.

OBJECTIVES

We assessed associations between numerous variables and both ferritin and sTfR concentrations in Cambodian women and compared ID prevalence through the use of study-generated correction factors (CFs) for ferritin with those from a published meta-analysis.

METHODS

Venous blood from 450 women (aged 18-45 y) was assessed for hemoglobin (Hb), ferritin, sTfR, retinol binding protein, folate, vitamin B-12, C-reactive protein, α-1 acid glycoprotein (AGP), and genetic Hb disorders. Linear regression was used to calculate geometric mean ratios (95% CIs) for ferritin and sTfR concentrations.

RESULTS

The variant Hb EE genotype was associated with 50% (14%, 96%) and 51% (37%, 66%) higher geometric mean ferritin and sTfR concentrations, respectively, than was the normal Hb AA genotype; a 1-g/L increase in AGP was associated with 99% (50%, 162%) and 48% (33%, 64%) higher concentrations in the same variables, respectively. ID prevalence in nonpregnant women (n = 420) was 2% (n = 9) with the use of ferritin <15 μg/L and 18% (n = 79) with the use of sTfR >8.3 mg/L as criteria. ID prevalence with the use of sTfR was higher in women with the Hb EE genotype (n = 17; 55%) than in those with the Hb AA genotype (n = 20; 10%); and in women with the Hb AA genotype and chronic inflammation (n = 10; 18%) than in that group of women without chronic inflammation (n = 10; 7%) (P < 0.05). No differences in ID prevalence were found with the use of ferritin between women with Hb EE and AA genotypes (P = 1.0) or by chronic inflammation status (P = 0.32). There were no differences in mean ferritin concentrations among all 450 women when study-generated CFs were compared with those from the meta-analysis (P = 0.87).

CONCLUSIONS

Compared with sTfR, ferritin concentrations appear to reflect more accurately true ID in rural Cambodian women. The CFs from a published meta-analysis were appropriate for use in this population with a high prevalence of Hb disorders and inflammation.

Maternal vitamin D₃ supplementation at 50 μg/d protects against low serum 25-hydroxyvitamin D in infants at 8 wk of age: a randomized controlled trial of 3 doses of vitamin D beginning in gestation and continued in lactation

BACKGROUND

Vitamin D supplementation is recommended for breastfed infants. Maternal supplementation beginning in gestation is a potential alternative, but its efficacy in maintaining infant 25-hydroxyvitamin D [25(OH)D] concentration after birth is unknown.

OBJECTIVES

We determined the effect of 3 doses of maternal vitamin D supplementation beginning in gestation and continued in lactation on infant serum 25(OH)D and compared the prevalence of infant serum 25(OH)D cutoffs (>30, >40, >50, and >75 nmol/L) by dose at 8 wk of age.

DESIGN

Pregnant women (n = 226) were randomly allocated to receive 10, 25, or 50 μg vitamin D₃/d from 13 to 24 wk of gestation until 8 wk postpartum, with no infant supplementation. Mother and infant blood was collected at 8 wk postpartum.

RESULTS

At 8 wk postpartum, mean [nmol/L (95% CI)] infant 25(OH)D at 8 wk was higher in the 50-μg/d [75 (67, 83)] than in the 25-μg/d [52 (45, 58)] or 10-μg/d [45 (38, 52)] vitamin D groups (P < 0.05). Fewer infants born to mothers in the 50-μg/d group had a 25(OH)D concentration <30 nmol/L (indicative of deficiency) than infants in the 25- and 10-μg/d groups, respectively (2% compared with 16% and 43%; P < 0.05). Fewer than 15% of infants in the 10- or 25-μg/d groups achieved a 25(OH)D concentration >75 nmol/L compared with 44% in the 50-μg/d group (P < 0.05). Almost all infants (∼98%, n = 44) born to mothers in the 50-μg/d group achieved a 25(OH)D concentration >30 nmol/L. At 8 wk postpartum, mean maternal 25(OH)D concentration was higher in the 50-μg/d [88 (84, 91)] than in the 25-μg/d [78 (74, 81)] or 10-μg/d [69 (66, 73)] groups (P < 0.05).

CONCLUSIONS

Maternal supplementation beginning in gestation with 50 μg vitamin D₃/d protects 98% of unsupplemented breastfed infants against 25(OH)D deficiency (<30 nmol/L) to at least 8 wk, whereas 10 or 25 μg vitamin D/d protects only 57% and 84% of infants, respectively.

Management of subclinical hypothyroidism in pregnancy: are we too simplistic?

Guideline advice of many societies on the management of subclinical hypothyroidism in pregnancy suggests treatment when TSH serum levels exceed 2.5 mU/l. Justification of this procedure is based on limited experience, mainly from studies carried out in patients with positive thyroid-specific antibodies and higher TSH levels that classically define the condition in the non-pregnant state. Taking into account a lack of clear understanding of the regulation of thyroid hormone transport through the utero-placental unit and in the absence of foetal markers to monitor the adequacy of thyroxine treatment, this review attempts to discuss currently available data and suggests a more cautious approach.

Iodine status in Danish pregnant and breastfeeding women including studies of some challenges in urinary iodine status evaluation

Denmark was previously iodine deficient with regional differences. Moderate iodine deficiency appeared in West Denmark and mild iodine deficiency in East Denmark and also Danish pregnant and breastfeeding women suffered from iodine deficiency. The Danish mandatory iodine fortification of salt was introduced in the year 2000 and has increased iodine intake in the Danish population. However, median urinary iodine concentration in the general population and in pregnant and breastfeeding women is still below the level recommended, corresponding to mild iodine deficiency. Certain characteristics may challenge the evaluation of urinary iodine status in pregnancy and during breastfeeding. This review also addresses methodological challenges related to spot urine sampling conditions and the use of iodine supplement and discusses the use of non-pregnant population groups as a proxy for iodine intake in pregnant women.

Highlights from the United States Food and Drug Administration's public workshop on the development of animal models of pregnancy to address medical countermeasures in an "at-risk" population of pregnant women: Influenza as a case study

The U.S. Food and Drug Administration (FDA) and other federal agencies partner to ensure that medical countermeasures (e.g., drug therapies and vaccines) are available for public health emergencies (FDA, 2014). Despite continuing progress, providing medical countermeasures and treatment guidelines for certain populations (e.g., pregnant women) is challenging due to the lack of clinical and/or animal data. Thus, a workshop was convened to discuss animal models of pregnancy for the evaluation of disease progression and medical countermeasures.

Challenges in the evaluation of urinary iodine status in pregnancy: the importance of iodine supplement intake and time of sampling

OBJECTIVES

Median urinary iodine concentration (UIC) is the recommended method to evaluate iodine status in pregnancy, but several factors may challenge the interpretation of the results. We evaluated UIC in pregnant women according to (1) sampling in the hospital versus at home, (2) time of the most recent iodine supplement intake prior to sampling, and (3) members of their household.

STUDY DESIGN

Danish cross-sectional study in the year 2012. Pregnant women (n = 158), their male partners (n = 157) and children (n = 51) provided a questionnaire with detailed information on iodine supplement intake and a spot urine sample obtained in the hospital and/or at home for measurement of UIC and urinary creatinine concentration.

RESULTS

In the pregnant women providing a urine sample both in the hospital and at home (n = 66), individual UIC (p = 0.002) and urinary creatinine concentration (p = 0.042), but not estimated 24-hour urinary iodine excretion (p = 0.79), were higher when sampling was at home. Median UIC was dependent on the time of the most recent iodine supplement intake prior to sampling [same day (n = 79): 150 µg/l (95% CI 131-181 µg/l), the day before (n = 51): 105 µg/l (78-131 µg/l), several days ago/non-user (n = 28): 70 µg/l (56-94 µg/l), p < 0.001]. The pattern was similar in the male partners. Apart from a more frequent iodine supplement intake in pregnancy (87.3% vs. partners 15.9%), no systematic differences were observed in urinary measurements between the pregnant women and their partners.

CONCLUSIONS

Time of spot urine sampling and time span from iodine supplement intake to spot urine sampling should be considered when evaluating urinary iodine status in pregnancy.

Optimizing anticancer drug treatment in pregnant cancer patients: pharmacokinetic analysis of gestation-induced changes for doxorubicin, epirubicin, docetaxel and paclitaxel

BACKGROUND

Pregnant patients with cancer are increasingly treated with anticancer drugs, although the specific impact of pregnancy-induced physiological changes on the pharmacokinetics (PK) of anticancer drugs and associated implications for optimal dose regimens remains unclear. Our objectives were to quantify changes in PK during pregnancy for four frequently used anticancer agents doxorubicin, epirubicin, docetaxel and paclitaxel, and to determine associated necessary dose adjustments.

PATIENTS AND METHODS

A pooled analysis of PK data was carried out for pregnant (Pr) and nonpregnant (NPr) patients for doxorubicin (n = 16 Pr/59 NPr), epirubicin (n = 14 Pr/57 NPr), docetaxel (n = 3 Pr/32 NPr) and paclitaxel (n = 5 Pr/105 NPr). Compartmental nonlinear mixed effect models were used to describe the PK and gestational effects. Subsequently, we derived optimized dose regimens aiming to match to the area under the concentration-time curve (AUC) in nonpregnant patients.

RESULTS

The effect of pregnancy on volumes of distribution for doxorubicin, epirubicin, docetaxel and paclitaxel were estimated as fold-change of <1.32, <2.08, <1.37 and <4.21, respectively, with adequate precision [relative standard error (RSE) <37%]. For doxorubicin, no gestational effect could be estimated on clearance (CL). For epirubicin, docetaxel and paclitaxel, a fold-change of 1.1 (RSE 9%), 1.19 (RSE 7%) and 1.92 (RSE 21%) were, respectively, estimated on CL. Calculated dose adjustment requirements for doxorubicin, epirubicin, docetaxel and paclitaxel were +5.5%, +8.0%, +16.9% and +37.8%, respectively. Estimated changes in infusion duration were marginal (<4.2%) except for paclitaxel (-21.4%).

CONCLUSION

Clinicians should be aware of a decrease in drug exposure during pregnancy and should not a priori reduce dose. The decrease in exposure was most apparent for docetaxel and paclitaxel which is supported by known physiological changes during pregnancy. The suggested dose adaptations should only be implemented after conduct of further confirmatory studies of the PK during pregnancy.

Semiphysiological versus empirical modelling of the population pharmacokinetics of free and total cefazolin during pregnancy

This work describes a first population pharmacokinetic (PK) model for free and total cefazolin during pregnancy, which can be used for dose regimen optimization. Secondly, analysis of PK studies in pregnant patients is challenging due to study design limitations. We therefore developed a semiphysiological modeling approach, which leveraged gestation-induced changes in creatinine clearance (CrCL) into a population PK model. This model was then compared to the conventional empirical covariate model. First, a base two-compartmental PK model with a linear protein binding was developed. The empirical covariate model for gestational changes consisted of a linear relationship between CL and gestational age. The semiphysiological model was based on the base population PK model and a separately developed mixed-effect model for gestation-induced change in CrCL. Estimates for baseline clearance (CL) were 0.119 L/min (RSE 58%) and 0.142 L/min (RSE 44%) for the empirical and semiphysiological models, respectively. Both models described the available PK data comparably well. However, as the semiphysiological model was based on prior knowledge of gestation-induced changes in renal function, this model may have improved predictive performance. This work demonstrates how a hybrid semiphysiological population PK approach may be of relevance in order to derive more informative inferences.

Pregnancy in diabetes and kidney disease

With appropriate multi-disciplinary team care, most women with diabetic nephropathy will have successful pregnancy outcomes; however, pregnancy complications are increased compared to non-diabetic individuals, particularly in those with poor glycaemic control. Women with more severe renal impairment, especially those with hypertension and proteinuria at are highest risk of worse pregnancy outcomes and deterioration in pre-existing renal function. Pre-pregnancy counselling should be offered to all women with diabetes in order to optimise diabetic care, and inform women of potential complications. Pregnancy is an indicator of long-term health, and may indicate important issues for the future management of women with diabetic nephropathy.

Leveraging physiological data from literature into a pharmacokinetic model to support informative clinical study design in pregnant women

PURPOSE

Physiological changes during pregnancy can effect pharmacokinetic (PK) parameters, which may lead to altered dose requirements. We aimed to leverage literature-based physiological changes during pregnancy into a PK model and compare its performance to a published reference model in pregnant women and to use the literature-based model to determine informative PK sampling times for a clinical study that aims to quantify the PK of enoxaparin throughout pregnancy.

METHODS

Changes in total body water (BW) and creatinine clearance (CRCL) during pregnancy were described using regression models. BW and CRCL were linked to a PK model of enoxaparin in non-pregnant women. Performance of the literature-based PK model was compared to a previously published empirical reference model. D-optimal sampling times were determined and evaluated for literature-based and reference models.

RESULTS

The literature-based model adequately predicted anti-Xa plasma concentrations when compared to reference model predictions. An informative sampling design was successfully developed, with parameters expected with good precision (RSE < 36.4%).

CONCLUSION

A literature-based model describing enoxaparin PK during pregnancy was developed and evaluated. The modelling framework could be used to support development of informative designs in pregnancy when prior models are unavailable.

Correlation of cystatin-C with glomerular filtration rate by inulin clearance in pregnancy

OBJECTIVE

To test utility of cystatin-C as a marker of glomerular filtration rate during pregnancy, we performed serial correlations with inulin clearance during pregnancy and postpartum.

METHODS

Twelve subjects received inulin infusions and serum cystatin-C at three time points. Pearson's correlation coefficient was calculated.

RESULTS

Cystatin-C levels ranged 0.66-1.48 mg/L during pregnancy, and 0.72-1.26 mg/L postpartum. Inulin clearance ranged 130-188 mL/min during pregnancy, and 110-167 mL/min postpartum. Cystatin-C did not correlate with inulin clearance at any time point.

CONCLUSION

Serum cystatin-C did not correlate with inulin clearance during pregnancy or postpartum.

A comparison of prediction equations for estimating glomerular filtration rate in pregnancy

OBJECTIVE

To compare existing glomerular filtration rate (GFR) prediction equations with the gold standard, inulin clearance, in pregnancy.

METHODS

Five equations were assessed for precision, bias, and accuracy in prediction of true GFR, measured by inulin clearance in 12 healthy, pregnant women during the second (T2) and third (T3) trimesters and in postpartum (PP).

RESULTS

Precision was greatest with 24-hour creatinine clearance estimation of GFR (R(2) = 13% (T2), R(2) = 26% (T3)). Other than 100/SCr, all equations underestimated true GFR. 30% accuracy was greatest in 100/SCr (83% (T2), 92% (T3)).

CONCLUSIONS

Current GFR prediction formulae do not appear to be sufficient for estimating GFR in the gravid state.

Intrauterine Growth Restriction in Spontaneously Hypertensive Rats

We examined the test profile of changes in systolic blood pressure (SBP), urinary volume, urinary sodium, and protein excretion in normotensive (Sprague Dawley) and spontaneously hypertensive rats (SHR) up to the 18th day of pregnancy. On days 6, 11, and 18 of pregnancy, the number of implantation sites, number of embryos, litter size, placenta, and litter weight were determined. In SHR, SBP (mmHg) increased significantly from the start of the test and remained high throughout the experiment. There was also a significant increase in urine volume (mL per 24 hrs) and urinary sodium excretion (mEq per 24 hrs) but no significant changes in protein excretion rate. The number of implantation sites on day 6 of pregnancy and the number of embryos on day 11 were similar in both groups. Uterus weight in SHR on days 6 and 11 of pregnancy was significantly lower than in normotensive rats. On day 18 of pregnancy in SHR, a substantial decrease in litter weight (7.10 +/- 0.40 vs. 12.00 +/- 0.92 g; p < 0.001) and weight of placenta (2.35 +/- 0.07 vs. 4.74 +/- 0.21 g; p < 0.001) was observed, with no modification in litter size. The hypertension associated with pregnancy in SHR increased urine volume and urinary sodium excretion and decreased weight of uterus, litter, and placenta relative to control rats.

Does glomerular hyperfiltration in pregnancy damage the kidney in women with more parities?

OBJECTIVES

We aimed to investigate the glomerular hyperfiltration due to pregnancy in women with more parities.

METHODS

Five hundred women aged 52.57 +/- 8.08 years, without a history of hypertension, diabetes mellitus or complicated pregnancy were involved in the study. They were divided into three groups. Group 1: women with no or one parity (n = 76); group 2: women with two or three parities (n = 333); group 3: women with four or more parities (n = 91). Laboratory parameters and demographical data were compared between the three groups.

RESULTS

Mean age, serum urea and serum creatinine were similar between three groups. Patients in group 3 had significantly higher GFR values compared to groups 1 and 2 (109.44 +/- 30.99, 110.76 +/- 30.22 and 121.92 +/- 34.73 mL/min/1.73 m(2) for groups 1, 2 and 3, respectively; P = 0.008 for group 1 vs group 3; P = 0.002 for group 2 vs group 3).

CONCLUSIONS

In our study, we suggest that glomerular hyperfiltration due to pregnancy does not have adverse effects on kidney in women with more parities. Pregnancy may have possible protective mechanisms for kidney against adverse effects of glomerular hyperfiltration.

Cyclical changes in endogenous overnight creatinine clearance during the third trimester of pregnancy

To investigate the pattern of change in endogenous overnight creatinine clearance during the third trimester, 12 healthy women with uncomplicated pregnancies were examined three times a week. Urine was collected overnight from 22.00 to 08.00 hours and analysed for creatinine. Serum was sampled in the morning and analysed for creatinine, beta 2-microglobulin, progesterone and estradiol. The general trend of creatinine clearance was parabolic with a declining level during the last month before term. A sinusoid pattern with minimum values around the time when the women would have had menstruation had they not become pregnant was superimposed on the parabolic trend. A mathematical model (parabolas overlaid with a cosine curve) was constructed and fitted to the data. The cyclical pattern was significant. Serum creatinine showed a pattern with increasing values during the last 4-6 weeks before term and cyclical changes which were also significant. In the individual case the monthly and preterm clearance decrement sometimes was over 50%. Monthly and preterm decreases in creatinine clearance may be quite normal and serial measurements of creatinine clearance are therefore necessary to determine if declining values indicate pathological falls in the glomerular filtration rate.

Clinical Significance of Proteinuria in Pregnancy

Urinary protein excretion is considered abnormal in pregnant women when it exceeds 300 mg/24 hours at anytime during gestation, a level that usually correlates with 1+ on urine dipstick. Proteinuria documented before pregnancy or before 20 weeks' gestation suggests preexisting renal disease. The National High Blood Pressure Education Program Working Group recommended that that the diagnosis of proteinuria be based on the 24-hour urine collection. Preeclampsia is the leading diagnosis that must be excluded in all women with proteinuria first identified after 20 weeks of gestation. Given the vasospastic nature of this condition, when it is present, the degree of proteinuria may fluctuate widely from hour-to-hour. Hypertension or proteinuria may be absent in 10-15% of patients with HELLP syndrome and in 38% of patients with eclampsia. The acute onset of proteinuria and worsening hypertension in women with chronic hypertension is suggestive of superimposed preeclampsia, which increases adverse outcomes. However, because proteinuria is not independently predictive of adverse outcome, an exclusive proteinuric criterion as an indication for preterm delivery in preeclampsia should be discouraged.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to state that measurement of urinary protein levels by simple techniques are not sensitive or specific, recall that both hypertension and proteinuria may be absent in patients with preeclampsia, and explain that proteinuria is not predictive of adverse outcomes and that delivery should not be based on protein excretion alone.

Cystatin-C and beta trace protein as markers of renal function in pregnancy

OBJECTIVE

To assess the validity of Cystatin-C (Cys-C) and beta trace protein (BTP) as clinical markers of glomerular filtration rate (GFR) in pregnant women.

DESIGN

Prospective cross sectional study.

SETTING

Obstetric unit of a tertiary care hospital.

POPULATION

One hundred and thirty-seven normal pregnant women and 13 women postpartum.

METHODS

Twenty-four hour creatinine clearance (CrCl), serum creatinine, Cys-C and BTP concentrations were measured on normal pregnant women in the first trimester (n= 5), second trimester (n= 68) and third trimester (n= 64) and in 13 women postpartum. Data are given as median (2.5th centile, 97.5th centile).

MAIN OUTCOME MEASURES

Serum concentrations of Cys-C and BTP compared with creatinine clearance and serum creatinine.

RESULTS

The median serum creatinine throughout gestation was 53 micromol/L (39, 71), and median CrCl was 143 mL/minute (91 to 216). Postpartum, creatinine rose to 74 micromol/L (58, 86) and CrCl decreased to 104 mL/minute (71, 159). For Cys-C, the median concentration was 0.70 mg/L (0.46, 1.32), and 0.54 mg/L (0.36, 0.96) for BTP. Comparing the second and third trimesters, there was no significant difference between CrCl (median 145 vs 141 mL/minute) and BTP concentrations (median 0.51 vs 0.55 mg/L), while median Cys-C was significantly higher in the third trimester (0.61 vs 0.88 mg/L; P < 0.001). Unlike creatinine and BTP, Cys-C levels decreased to 0.72 mg/L (0.57, 0.95) postpartum. The only significant relationship of either of these markers to the standard used for GFR was between Cys-C and CrCl in the third trimester, and the correlation was weak (r= 0.27 for 1/Cys-C vs CrCl).

CONCLUSION

These data demonstrate that despite claims to the contrary, Cys-C is a poor marker of GFR during pregnancy. Similarly, BTP shows little promise.

Psychotropic drugs in pregnancy and lactation

The management of psychotropic medications during pregnancy and lactation involves a difficult and complex decision for both patient and provider, particularly due to the many unknown effects medication may have on the infant. Available studies concerning use of psychotropic medications in pregnant and lactating women are limited and there are no universal guidelines. This article reviews the literature on the use of psychotropic drugs, including antidepressants, mood stabilizers, antipsychotics, and benzodiazepines, in pregnant and breast-feeding women and presents relevant data on teratogenic effects, neonatal toxicity, perinatal syndromes, and neurobehavioral sequelae.

Renal venous Doppler sonography in preeclampsia

OBJECTIVE

The elevation in blood pressure associated with preeclampsia appears to be associated with a shift in the renal pressure natriuresis curve. Pressure natriuresis is modulated by renal medullary pressure. In obstructive uropathy, Doppler sonography has been used to indicate changes in renal venous impedance, possibly measuring alterations in medullary pressure and compliance in this condition. The hypothesis tested in this study was that an elevation in renal venous pulsation may occur in preeclampsia compared with normal pregnancy.

METHODS

Seven patients with clinical evidence of preeclampsia were referred for fetal well-being confirmation by sonography in the third trimester. Seven pregnant patients without renal disease or hypertension reviewed in the third trimester served as a control group. Doppler studies of the interlobar arteries and veins of both kidneys were performed, with a total of 14 kidneys imaged per group. Arterial and venous impedance indices were obtained. The impedance indices for the patients were compared by the Student t test.

RESULTS

No significant difference was noted between the arterial resistive indices. The mean venous impedance index for the hypertensive patients was 0.50 +/- 0.12, and that for the control patients was 0.37 +/- 0.06 (P = .003).

CONCLUSIONS

Preeclampsia in the third trimester appears to be associated with altered medullary venous pulsation, possibly indicating reduced medullary pressure.

Maternal plasma hypertonicity is accentuated in the postterm rat

OBJECTIVE

In humans and rats, pregnancy-associated maternal plasma volume expansion and plasma hypotonicity may facilitate maternal-to-fetal water transfer. Although reduced amniotic fluid volume occurs commonly in postterm pregnancy, the mechanisms are unknown. We previously demonstrated a reversal of pregnancy-induced maternal plasma hypotonicity that occurs in the near term (20 days) pregnant rats. We sought to determine whether the relative maternal plasma hypertonicity continues in the postterm period.

STUDY DESIGN

Rat gestation (normal, 21 days) was prolonged with subcutaneous progesterone injection. Pregnant rats at gestation, 18 days, 21 days, and 24 days and nonpregnant rats were studied. Maternal and fetal hematocrit levels, plasma osmolality, electrolyte levels, and amniotic fluid volume were determined. In addition, maternal and fetal tissues were analyzed for water and electrolyte content.

RESULTS

Compared with term (21days), postterm pregnant rats (24 days) had a significant increase in maternal and fetal plasma osmolality (293.7+/-1.4 mOsm/kg vs 302.8+/-3.7 mOsm/kg and 301.0+/-2.0 mOsm/kg vs 310.3+/-3.2 mOsm/kg, respectively; P<.01) and sodium and chloride concentrations. Conversely, both maternal and fetal hematocrit levels decreased significantly in the postterm period. Postterm rats demonstrated an increased fetal mortality rate (24%) and a significantly reduced amniotic fluid volume (4.2+/-0.6 mL vs 6.6+/-0.6 mL, P<.01).

CONCLUSION

These results indicate that the near-term reversal of maternal plasma hypotonicity that has been observed previously is further accentuated in the postterm pregnancy. This continued hypertonicity may induce a fetal-to-maternal water flow and contribute to postterm oligohydramnios and increased fetal morbidity and mortality rates.

Reversal of pregnancy-mediated plasma hypotonicity in the near-term rat

OBJECTIVE

Maternal plasma hypotonicity occurs early in rat and human pregnancy with resetting of the plasma osmolality threshold for vasopressin secretion and thirst. In humans, amniotic fluid volume reaches maximum levels in the mid-third trimester and decreases thereafter. We hypothesized that a reversal of maternal plasma hypotonicity occurs near term, contributing to reduced fetal and amniotic fluid water content.

METHODS

Maternal plasma and amniotic fluid osmolality and sodium levels, including amniotic fluid volume, were measured at 16, 18 and 20 days of rat gestation. Additionally, maternal and fetal brains were analyzed for water and electrolyte content. Non-pregnant adult female rats represented controls.

RESULTS

Compared to non-pregnant adults, 16-day and 18-day pregnant rats had significantly lower plasma osmolality (301.0 +/- 2.3 vs. 295.4 +/- 2.8 and 289.7 +/- 3.3 mOsm/kg, respectively) and sodium levels (140.3 +/- 1.0 vs. 135.7 +/- 0.8 and 133.4 +/- 1.4 mEq/l, respectively). Conversely, 20-day pregnant rats showed no significant difference in plasma osmolality (298.4 +/- 3.1 mOsm/kg) or sodium levels (137.6 +/- 1.0 mEq/l) from non-pregnant adults. With advancing gestation, the amniotic fluid volume decreased whereas the osmolality and sodium levels increased significantly. Maternal brain water content was significantly higher in 16-day and 18-day pregnant rats compared to control rats (78.7 +/- 0.1 and 78.1 +/- 0.2 vs. 76.9 +/- 0.2% wet weight) and returned to non-pregnant values in the 20-day pregnant rats (76.6 +/- 0.2%). In association with the maternal changes, fetal brain water and electrolyte content significantly decreased from 16-day to 18-day to 20-day fetuses.

CONCLUSION

These findings indicate a reversal of maternal plasma hypotonicity and reduced maternal brain water content in the near-term pregnant rat. We speculate that relative maternal plasma hypertonicity near term may contribute to reduced amniotic fluid volume.

Impact of pregnancy on underlying renal disease

Normal pregnancy involves marked renal vasodilation and large increases in glomerular filtration rate (GFR). Studies in rats reveal that the gestational renal vasodilation is achieved by parallel reductions in tone in afferent and efferent arterioles so GFR rises without a change in glomerular blood pressure. There is some evidence from animal studies that increased renal generation of nitric oxide (NO) may be involved. Although chronic renal vasodilation has been implicated in causing progression of renal disease in nonpregnant states by glomerular hypertension, there are no long-term deleterious effects of pregnancies on the kidney when maternal renal function is normal because glomerular blood pressure remains normal. When maternal renal function is compromised before conception, there are no long-term adverse effects on renal function in most types of renal disease, providing that the GFR is well maintained before conception. When serum creatinine exceeds approximately 1.4 mg/dL, pregnancy may accelerate the renal disease increases and when serum creatinine >2 mg/dL, the chances are greater than 1 in 3 that pregnancy will hasten the progression of the renal disease. The available animal studies suggest that glomerular hypertension does not occur despite diverse injuries. Thus, the mechanisms of the adverse interaction between pregnancy and underlying renal disease remain unknown.

Lymphocyte propionyl-CoA carboxylase and accumulation of odd-chain fatty acid in plasma and erythrocytes are useful indicators of marginal biotin deficiency small star, filled

BACKGROUND: Recent studies indicate marginal biotin deficiency is more common than previously thought. That conclusion's validity rests on two indicators of biotin status that depend on renal function.OBJECTIVE: Assessing the validity of two indicators of biotin status that do not depend upon renal function: 1) activity of the biotin-dependent enzyme propionyl-CoA carboxylase (PCC) in lymphocytes and 2) accumulation of odd-chain fatty acids in the lipids of plasma and erythrocytes.DESIGN: Marginal biotin deficiency was induced in 11 healthy adults by egg-white feeding for 28 days. Blood and 24-h urine samples were collected before commencing the diet and twice weekly thereafter. After depletion, biotin status was restored with a general diet with or without 80 &mgr;g/day or 328 nmol/day biotin supplement. Activity of PCC was determined by an optimized NaH 14CO(3) incorporation assay. Fatty acid composition was determined by gas chromatography.RESULTS: With time on the egg-white diet, lymphocyte PCC activity decreased significantly (P <0.0001); C15:0 and C17:0 content increased significantly in the lipids of plasma and erythrocytes (P <0.015). In eight of 11 subjects, lymphocyte PCC activity returned to normal within three weeks of resuming general diets with or without biotin supplement. With repletion, C15:0 and C17:0 in plasma lipids decreased (P <0.02), but odd-chain content of erythrocytes did not decrease significantly.CONCLUSIONS: Lymphocyte PCC activity is an early and sensitive indicator of marginal biotin deficiency. Odd-chain fatty acids accumulate in blood lipids more gradually during marginal deficiency and return to normal more gradually after biotin repletion.