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Beers K, Patel N. Kidney Physiology in Pregnancy. Adv Chronic Kidney Dis 2020; 27:449-454. [PMID: 33328060 DOI: 10.1053/j.ackd.2020.07.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 11/11/2022]
Abstract
A woman's body undergoes a myriad of changes throughout the course of a normal gestation. The kidneys play a central role in driving adjustments that guarantee maternal and fetal well-being, including a dramatic increase in glomerular filtration rate, alterations in tubular function, and changes in electrolyte and acid/base handling. Early in gestation, systemic vasodilation, driven by both a change in quantity of and response to various hormones, leads to increased renal blood flow and glomerular filtration rate. Vasodilation also results in activation of the renin-angiotensin-aldosterone axis, which combined with changing tubular handling causes alterations in total body stores of electrolytes and total body water, resulting in a lower serum sodium concentration. In addition, mild proteinuria, glucosuria, and a decrease in serum calcium and magnesium are common. The primary acid/base change seen in pregnancy is a mild respiratory alkalosis due to progesterone effects. This article provides an overview of the current understanding of the healthy response of the kidneys to pregnancy, an understanding of which is key to caring for the pregnant patient, and early identification of alterations that may indicate underlying kidney pathology in pregnancy.
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Fotiou M, Fotakis C, Tsakoumaki F, Athanasiadou E, Kyrkou C, Dimitropoulou A, Tsiaka T, Chatziioannou AC, Sarafidis K, Menexes G, Theodoridis G, Biliaderis CG, Zoumpoulakis P, Athanasiadis AP, Michaelidou AM. 1H NMR-based metabolomics reveals the effect of maternal habitual dietary patterns on human amniotic fluid profile. Sci Rep 2018; 8:4076. [PMID: 29511239 PMCID: PMC5840288 DOI: 10.1038/s41598-018-22230-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 02/13/2018] [Indexed: 12/25/2022] Open
Abstract
Maternal diet may influence offspring’s health, even within well-nourished populations. Amniotic fluid (AF) provides a rational compartment for studies on fetal metabolism. Evidence in animal models indicates that maternal diet affects AF metabolic profile; however, data from human studies are scarce. Therefore, we have explored whether AF content may be influenced by maternal diet, using a validated food-frequency questionnaire and implementing NMR-based metabolomics. Sixty-five AF specimens, from women undergoing second-trimester amniocentesis for prenatal diagnosis, were analysed. Complementary, maternal serum and urine samples were profiled. Hierarchical cluster analysis identified 2 dietary patterns, cluster 1 (C1, n = 33) and cluster 2 (C2, n = 32). C1 was characterized by significantly higher percentages of energy derived from refined cereals, yellow cheese, red meat, poultry, and “ready-to-eat” foods, while C2 by higher (P < 0.05) whole cereals, vegetables, fruits, legumes, and nuts. 1H NMR spectra allowed the identification of metabolites associated with these dietary patterns; glucose, alanine, tyrosine, valine, citrate, cis-acotinate, and formate were the key discriminatory metabolites elevated in C1 AF specimens. This is the first evidence to suggest that the composition of AF is influenced by maternal habitual dietary patterns. Our results highlight the need to broaden the knowledge on the importance of maternal nutrition during pregnancy.
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Affiliation(s)
- Maria Fotiou
- Department of Food Science and Technology, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Charalambos Fotakis
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece
| | - Foteini Tsakoumaki
- Department of Food Science and Technology, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Elpiniki Athanasiadou
- 1st Department of Obstetrics and Gynecology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Charikleia Kyrkou
- Department of Food Science and Technology, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Aristea Dimitropoulou
- Department of Food Science and Technology, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Thalia Tsiaka
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece
| | | | - Kosmas Sarafidis
- 1st Department of Neonatology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - George Menexes
- Department of Field Crops and Ecology, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Costas G Biliaderis
- Department of Food Science and Technology, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Panagiotis Zoumpoulakis
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece.
| | - Apostolos P Athanasiadis
- 3rd Department of Obstetrics and Gynecology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| | - Alexandra-Maria Michaelidou
- Department of Food Science and Technology, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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Sachse D, Bærug A, Sletner L, Birkeland KI, Nakstad B, Jenum AK, Berg JP. Urine NMR metabolomics analysis of breastfeeding biomarkers during and after pregnancy in a large prospective cohort study. Scandinavian Journal of Clinical and Laboratory Investigation 2014; 74:264-72. [PMID: 24621206 DOI: 10.3109/00365513.2014.884240] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Modern metabolomic profiling has not yet been applied to human breastfeeding research. A common reason for breastfeeding cessation is perceived insufficient milk production. We investigated broad biochemical profiles in maternal urine collected during and after pregnancy to identify biomarkers related to reduced reported breastfeeding. METHODS Fasting urine was collected at three consultations (visit V1: gestational week 8-20; V2: week 28 ± 2; V3: 10-16 weeks postpartum) in the STORK Groruddalen program, a prospective, multiethnic cohort study of gestational diabetes involving healthy, pregnant women in Oslo, Norway, and analyzed using NMR spectroscopy. Breastfeeding at V3 was recorded in three categories: Exclusively breastfeeding (n = 326), partially breastfeeding (n = 156) and formula feeding (n = 67). RESULTS Five metabolites were relevant to breastfeeding. Lactose was detected at V1 and increased to 0.1 mM/mM creatinine at V2. Postpartum excretion at V3 was significantly higher in exclusively breastfeeding women than partially or non-breastfeeding (median = 0.29, 0.23 and 0.04 mM/mM creatine, respectively; ANOVA p-value = 2e-70). Glycine excretion at V3 (0.12, 0.10 and 0.06, respectively; p = 2e-5) and at V2 were associated with breastfeeding (0.34, 0.33 and 0.26, respectively; p = 4e-5). Creatine and two unidentified substances also correlated with breastfeeding. NMR metabolomics found no other metabolites differing between categories during pregnancy (V1, V2), and did not predict individual breastfeeding postpartum (V3). CONCLUSION Decreased glycine excretion at V2 may indicate difficulties meeting the metabolic demands of the growing fetus, but urine profiles contained otherwise little indication of early adaptations during pregnancy towards reduced biological potential to breastfeed.
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Affiliation(s)
- Daniel Sachse
- Department of Medical Biochemistry, University of Oslo , Oslo , Norway
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Toka HR, Yang J, Zera CA, Duffield JS, Pollak MR, Mount DB. Pregnancy-associated polyuria in familial renal glycosuria. Am J Kidney Dis 2013; 62:1160-4. [PMID: 23871407 DOI: 10.1053/j.ajkd.2013.05.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 05/15/2013] [Indexed: 11/11/2022]
Abstract
A pregnant woman presented at gestational week 28 with loss of consciousness and profound polyuria. Further characterization revealed osmotic diuresis due to massive glycosuria without hyperglycemia. Glycosuria reduced substantially postpartum, from approximately 100 to approximately 30 g/1.73 m2 per day. DNA sequencing analysis of the SLC5A2 gene encoding the renal glucose transporter SGLT2 showed a homozygous frame-shift mutation (occurring after the glutamine at amino acid 168 and leading to premature termination of the protein at amino acid 186) diagnostic of familial renal glycosuria. Pregnant women with familial renal glycosuria can be at risk of profound polyuria during pregnancy due to the associated increase in glycosuria. These findings also have implications for the use of SGLT2 inhibitors in clinical practice.
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Affiliation(s)
- Hakan R Toka
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, MA; Division of Nephrology, Brigham and Women's Hospital, Boston, MA
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Odutayo A, Hladunewich M. Obstetric Nephrology: Renal Hemodynamic and Metabolic Physiology in Normal Pregnancy. Clin J Am Soc Nephrol 2012; 7:2073-80. [DOI: 10.2215/cjn.00470112] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Bröer S. The role of the neutral amino acid transporter B0AT1 (SLC6A19) in Hartnup disorder and protein nutrition. IUBMB Life 2009; 61:591-9. [PMID: 19472175 PMCID: PMC7165679 DOI: 10.1002/iub.210] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Hartnup disorder (OMIM 234500) is an autosomal recessive disorder, which was first described in 1956 as an aminoaciduria of neutral amino acids accompanied by a variety of symptoms, such as a photo‐sensitive skin‐rash and cerebellar ataxia. The disorder is caused by mutations in the neutral amino acid transporter B0AT1 (SLC6A19)1. To date 21 mutations have been identified in more than twenty families. SLC6A19 requires either collectrin or angiotensin‐converting enzyme 2 for surface expression in the kidney and intestine, respectively. This ties SLC6A19 together with more complex functions such as blood‐pressure control, glomerular structure, and exocytosis. © 2009 IUBMB IUBMB Life, 61(6): 591–599, 2009
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Affiliation(s)
- Stefan Bröer
- School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, Australian Capital Territory, Australia.
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Abstract
The [2H5]-phenylalanine method for measurement of protein metabolism requires the phenylalanine hydroxylation to tyrosine to be calculated from the tyrosine flux. Although this can be estimated, for pregnancy, we made a direct measurement of the molar ratio of the fluxes of tyrosine and phenylalanine from protein breakdown (Pt/Pp) using [2H2]-tyrosine infusion. Six normal pregnant women were studied at 37 weeks' gestation. While fasting, they were administered a 3-hour primed-constant infusion with [13C]-leucine, [2H5]-phenylalanine, and [2H2]-tyrosine. Leucine (alpha-ketoisocaproic acid [KIC]) flux was 136.2+/-15.1 micromol/kg/h (mean +/- SD), phenylalanine flux 41.2+/-5.6, and tyrosine flux 25.0+/-6.0, and phenylalanine hydroxylation was 3.3+/-2.1 micromol/kg/h. The mean tyrosine to phenylalanine molar flux ratio (Pt/Pp) was 0.52+/-0.10, lower than the ratio of 0.65 to 0.85 reported in normal nonpregnant subjects and 0.73 estimated from animal studies. We studied protein metabolism in six additional pregnant women and six nonpregnant women using [13C]-leucine and [2H5]-phenylalanine infusions only and applied the lower Pt/Pp ratio to the former group. Tyrosine flux (42.0+/-7.2 micromol/kg/h) and phenylalanine hydroxylation (9.2+/-4.2 micromol/kg/h) were significantly higher in nonpregnant subjects than in both groups of pregnant subjects. The percent contribution of phenylalanine hydroxylation to total tyrosine flux was reduced from 20% to 14%. When using [2H5]-phenylalanine to study whole-body protein metabolism in pregnancy and tyrosine flux is not measured directly by infusion of [2H2]-tyrosine, the lower Pt/Pp ratio is required. The phenylalanine model shows that tyrosine flux derived from protein breakdown and phenylalanine hydroxylation are both reduced in pregnancy.
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Affiliation(s)
- P G Whittaker
- University Department of Obstetrics & Gynecology, Royal Victoria Infirmary, Newcastle, Tyne and Wear, England
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Jackson AA, Persaud C, Werkmeister G, McClelland IS, Badaloo A, Forrester T. Comparison of urinary 5-L-oxoproline (L-pyroglutamate) during normal pregnancy in women in England and Jamaica. Br J Nutr 1997; 77:183-96. [PMID: 9135366 DOI: 10.1079/bjn19970023] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Urinary 5-L-oxoproline was measured during normal pregnancies in Southampton, England and Kingston, Jamaica. The CV of 5-L-oxoproline excretion in urine, determined over 7 d in a non-pregnant woman and three pregnant women, was 10-36%. Compared with non-pregnant women, urinary 5-L-oxoproline increased three to four times from early pregnancy in women in Southampton, a highly significant difference, and remained elevated at similar levels during mid and late pregnancy. For women in Kingston, the excretion of 5-L-oxoproline was similar to that of Southampton women in the non-pregnant group and during early pregnancy. However, there was a progressive increase in the excretion of 5-L-oxoproline as pregnancy advanced and by late pregnancy excretion was from three to ten times greater than the average for the non-pregnant women. There was a significant difference between the women in Southampton and the women in Kingston during mid and late pregnancy, with women in Kingston excreting twice as much 5-L-oxoproline during late pregnancy. If the excretion of 5-L-oxoproline is a measure of glycine insufficiency, the results would indicate that in some pregnancies the ability of the mother to provide glycine for herself and the developing fetus is marginal or inadequate and the constraint appears more marked in Jamaica than in England.
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Affiliation(s)
- A A Jackson
- Institute of Human Nutrition, University of Southampton
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Jackson DW, Carder EA, Voss CM, Fry DE, Glew RH. Altered urinary excretion of lysosomal hydrolases in pregnancy. Am J Kidney Dis 1993; 22:649-55. [PMID: 8238009 DOI: 10.1016/s0272-6386(12)80426-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Creatinine concentrations and the activities of five lysosomal hydrolases were measured in the serum and urine of 14 healthy nonpregnant control women and 19 healthy pregnant women. Fractional enzyme excretion (FEE) values for beta-glucuronidase, beta-hexosaminidase, alpha-galactosidase, beta-galactosidase, and alpha-mannosidase were calculated and compared between the two groups of subjects. Fractional enzyme excretion was calculated as the ratio of enzyme clearance to creatinine clearance. The FEE values for beta-galactosidase and alpha-mannosidase between the nonpregnant and pregnant populations were not statistically different; however, relative to the nonpregnant control group, the median FEE values for beta-glucuronidase (P < 0.03), beta-hexosaminidase (P < 0.06), and alpha-galactosidase (P < 0.02) were decreased approximately 1.5-, 1.8-, and 2.7-fold, respectively, in the pregnant population. The median urinary beta-galactosidase activity for the pregnant population, when expressed on the basis of creatinine, was twofold higher than that of the control group (P < 0.0005). These data indicate that with pregnancy there are marked changes in the urinary excretion of selected lysosomal enzymes, particularly alpha-galactosidase and beta-glucuronidase. When the molecular weights of these five hydrolases were compared between kidney homogenate and control urine, a correlation of 0.96 was observed, while the correlation between control serum and control urine was 0.69. This suggests that the FEE value differences between the pregnant and control groups are most likely due to changes in tubule cell metabolism, either decreased secretion or increased reabsorption. These biochemical changes may provide a means of assessing changes in renal function during pregnancy.
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Affiliation(s)
- D W Jackson
- Department of Biochemistry, University of New Mexico School of Medicine, Albuquerque 87131
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10
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Abstract
Many changes in renal function occur in normal pregnancy. Without a proper understanding of these changes, routine clinical investigations may easily be misinterpreted. Women with preeclampsia have further alterations in renal function and, in occasional cases, develop acute renal failure. Understanding of abnormal renal physiology and hormonal changes in these women allows the clinician to interpret biochemical tests appropriately and make proper use of vasodilator therapy with careful attention to volume homeostasis. Women who undertake pregnancy with a primary renal disease, most commonly glomerulonephritis or reflux nephropathy, have a higher risk of adverse fetal and maternal outcomes. Awareness of these risks provides a basis for proper preconceptual counseling, as well as careful monitoring of maternal blood pressure and renal function and fetal growth during such pregnancies. These strategies will optimize the chances of a successful pregnancy outcome for both mother and baby.
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Affiliation(s)
- M A Brown
- Department of Renal Medicine, St George Hospital, Kogarah, NSW, Australia
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11
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Abstract
Marked changes in renal function occur with pregnancy. We present a summary of these changes in this review and give insight into possible mechanisms if they are known. Controversies exist regarding the therapy of pregnancy-induced hypertension and asymptomatic and recurrent bacteriuria. The current views on these topics are given. Specific renal diseases are summarized, including transplantation, and optimum management strategies and maternal and fetal prognosis during pregnancy are given.
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Affiliation(s)
- E Dafnis
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock 79430
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13
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Persaud C, McDermott J, De Benoist B, Jackson AA. The excretion of 5-oxoproline in urine, as an index of glycine status, during normal pregnancy. BRITISH JOURNAL OF OBSTETRICS AND GYNAECOLOGY 1989; 96:440-4. [PMID: 2751957 DOI: 10.1111/j.1471-0528.1989.tb02420.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The urinary excretion of 5-oxoproline, which may be used as an index of glycine status, was investigated in 30 normal pregnant women during different stages of pregnancy and in 18 non-pregnant female volunteers. During an 18-h study there was little variation in the 5-oxoproline/creatinine index, and a single sample gave a representative value. The excretion of 5-oxoproline/creatinine (mumol/mmol) rose progressively as pregnancy advanced (non-pregnant mean 10, SD 5, first trimester mean 46, SD 12, second trimester mean 150, SD 180, and third trimester mean 280, SD 320) and by the third trimester was over 20 times greater than in non-pregnant women. The data suggest that as pregnancy advances the endogenous production of glycine may be insufficient to satisfy the increasing demands.
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Affiliation(s)
- C Persaud
- Tropical Metabolism Unit, University of the West Indies, Kingston, Jamaica
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Reece EA, Coustan DR, Hayslett JP, Holford T, Coulehan J, O'Connor TZ, Hobbins JC. Diabetic nephropathy: pregnancy performance and fetomaternal outcome. Am J Obstet Gynecol 1988; 159:56-66. [PMID: 3394754 DOI: 10.1016/0002-9378(88)90494-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A study of 31 continuing pregnancies complicated by diabetic nephropathy was conducted to determine the effects of diabetes-associated renal disease on maternal health and fetal outcome. Throughout pregnancy there was a significant increase in maternal blood pressure (p less than 0.001) and proteinuria (p less than 0.0001), with nephrotic syndrome (greater than 3.0 gm protein/day) developing in 71% of pregnancies. After birth, however, proteinuria reverted to levels not significantly different from values in early pregnancy. There was no apparent adverse effect of pregnancy on the natural course of the underlying renal disease. Stillbirths occurred in two patients (6%), and the remaining 29 pregnancies resulted in live-births at a mean gestational age of 36 weeks. Seventy percent of these infants were appropriate for gestational age, whereas 16% were small and 13% were large for gestational age. Birth weight was best correlated with gestational age and creatinine clearance (p less than 0.0001). Neonatal complications included respiratory distress syndrome (19%), hyperbilirubinemia (26), and congenital malformations (10%). The uncorrected perinatal survival rate was 94%. These data suggest that with contemporary methods of maternal evaluation and treatment, fetal surveillance, and neonatal care, the risks to patients with diabetic nephropathy during pregnancy are not excessive. The likelihood of a successful fetal and neonatal outcome is comparable to that in other patients with insulin-dependent diabetes.
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Affiliation(s)
- E A Reece
- Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, CT 06510
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Affiliation(s)
- D M Campbell
- Department of Obstetrics and Gynaecology, University of Aberdeen, Foresterhill
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Abstract
A simple method is presented for measurement of urinary 3-methylhistidine (3MH) using a cationic exchange resin treatment followed by colorimetric analysis. Equations are given to correct for the interference by histidine (4.3% by mole) in the colorimetric analysis. This correction is especially important for measurement of urinary 3MH in pregnant women or in other subjects with elevated histidine excretion. Good recovery of added standard and good reproducibility of results are documented. Preliminary data from a study of pregnant women are reported, suggesting an increased excretion of 3MH during pregnancy. Large day-to-day variability of 3MH excretion was observed within subjects. It is recommended that repeated measurements be done on each subject when determining 3MH excretion.
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Acosta PB, Stepnick-Gropper S. Problems related to diet management of maternal phenylketonuria. J Inherit Metab Dis 1986; 9 Suppl 2:183-201. [PMID: 2877116 DOI: 10.1007/bf01799703] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Provision of nutritionally complete elemental diets for pregnant women with PKU requires greater knowledge of 'conditionally' essential nutrient requirements than is presently available as well as application of known information. Formulation of elemental products needs to be improved to enhance aroma and taste and to decrease osmolality. Designers of the metal and vitamin components should keep in mind that a major portion (70-80%) of most of these nutrients must be obtained from the elemental products. Thus deletion of suspected essential minerals or vitamins could cause serious deficiencies. On the other hand, knowledge of appropriate ratios that make for improved trace metal absorption should be applied. Clinical nutritionists need to assist patients in selection of foods that are low in binding substances and provide 'conditionally' essential nutrients in adequate amounts. Closer cooperation between clinical nutritionists, nutrition scientists and food technologists should result in improved elemental products for care of pregnant women with PKU.
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Regulation of Partition of Protein During Pregnancy. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/b978-0-12-153205-5.50012-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
The proximal nephron is responsible for reabsorbing 80 to 99 percent of several filtered solutes, including amino acids, glucose and bicarbonate. Separate, high-affinity sodium co-transport mechanisms are used. Increasing luminal concentration of each of these solutes stimulates its active transcellular reabsorption until there is saturation. Slightly less than half of the filtered chloride is reabsorbed, partly by passive mechanisms that are linked to the reabsorption of organic solutes and bicarbonate, as well as by less well defined independent cellular and/or paracellular mechanisms that appear to be sensitive to transepithelial osmotic pressure gradients. Proximal tubule reabsorption is isosmotic and isonatric, and about 50 to 60 percent of the filtered sodium and water in reabsorbed. Disorders or proximal nephron function include conditions in which luminal, cellular and/or peritubular factors affecting reabsorption are altered. Clinical disorders caused by modification of the luminal reabsorptive determinants include conditions in which tubular flow rate is increased or luminal composition is altered, as when non-reabsorbable solutes (mannitol) are filtered or when reabsorbable solutes (glucose) are filtered in concentrations exceeding their tubular transport capacity. Other disorders occur due to loss of affinity or capacity of the cellular active transport systems for specific solutes, such as amino acids (renal aminoacidurias), glucose (renal glycosurias) and bicarbonate (proximal renal tubular acidosis), or for all solutes (Fanconi syndrome). Finally, disorders due to changes in the peritubular factors affecting reabsorption include states of altered peritubular Starling forces or pH, which modify sodium chloride or sodium bicarbonate reabsorption, respectively.
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Abstract
The changes which occur in renal excretory function during pregnancy are discussed. The relationship between glomerular filtration rate and effective renal plasma flow is examined in the light of new serial data obtained under conditions of saline diuresis. Changes in the renal handling of nutrients and in the excretion of waste products during pregnancy are reviewed.
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Nutrition and Pregnancy. Nutrition 1979. [DOI: 10.1007/978-1-4615-7210-7_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Abstract
Plasma amino acid analyses on 27 amino acids in serial samples from 15 pregnancies in 14 patients are reported. Variations of amino acid levels with gestational age are reported both for absolute amino acid levels and for levels normalized to total amino acids, with a t test used to determine which amino acids vary significantly. The extent to which individual results differ from the means is indicated. Correlation and regression analyses were done for each amino acid vs. every other amino acid and for each amino acid vs. gestational age. Significant differences were found in amino acid results for plasma from an individual in whom pregnancy resulted in spontaneous abortion.
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Metzger BE, Unger RH, Freinkel N. Carbohydrate metabolism in pregnancy. XIV. Relationships between circulating glucagon, insulin, glucose and amino acids in response to a "mixed meal" in late pregnancy. Metabolism 1977; 26:151-6. [PMID: 834148 DOI: 10.1016/0026-0495(77)90050-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Gestational influences upon the changes in circulating glucose, amino acids, insulin, and glucagon after the ingestion of a "mixed meal" containing carbohydrate (50 g), protein (25 g), and fat (10 g) were examined. Nine subjects were tested during weeks 30-40 of gestation and again 6--8 wk postpartum. The "mixed meal" elicited greater and more prolonged increases in plasma glucose anterpartum, whereas the increments in total serum amino acids were blunted at all time points. In the face of greater glycemic but lesser aminogenic stimulation, the integrated increase in plasma insulin was 60% greater antepartum than post partum, whereas the increment in glucagon was not significantly altered. Thus, integrated insulin/glucagon response was increased during antepartum studies. The insulin preponderance following alimentary challenge with mixed nutrients would suggest that the anabolism of ingested amino acids is "facilitated" during late human pregnancy.
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Abstract
A scheme is described for the investigation and management of a renal transplant recipient before conception, over conception and during the subsequent pregnancy, delivery and puerperium. The patient showed the physiological changes in homeostasis of normal pregnancy. Methods of monitoring maternal, fetal and renal well-being are discussed. The patient was delivered of a live male child and the neonatal problems are described. The puerperium was uneventful.
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LINDHEIMER MARSHALLD, KATZ ADRIANI. Renal Changes during Pregnancy: Their Relevance to Volume Homeostasis. ACTA ACUST UNITED AC 1975. [DOI: 10.1016/s0306-3356(21)00299-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
A feature of normal pregnancy is a huge increase in the excretion of nutrients in urine. Glycosuria is commonplace, and about half of all healthy pregnant women excrete more than when not pregnant. Amounts in excess of 1 g/24 hr are common, and excretion is characteristically intermittent with little apparent relation to plasma levels. Amino acid excretion is also raised four or five times by late pregnancy, with a characteristic pattern for different amino acids, and folate and other water soluble vitamins are similarly squandered. The mechanisms are not understood.
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Lind T, Hytten FE. The excretion of glucose during normal pregnancy. THE JOURNAL OF OBSTETRICS AND GYNAECOLOGY OF THE BRITISH COMMONWEALTH 1972; 79:961-5. [PMID: 4642380 DOI: 10.1111/j.1471-0528.1972.tb11870.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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