Amerlex free triiodothyronine and free thyroxine levels in normal pregnancy

Free triiodothyronine (FT3) and free thyroxine (FT4) were measured in 159 women during normal pregnancy and compared with non-pregnancy reference ranges for these hormones. FT3 values fell from the reference level of 6.34 (SD 1.06) pmol/l to 3.87 (SD 0.54) pmol/l in the 3rd trimester; corresponding figures for FT4 were: reference 16.92 (SD 2.97) pmol/l, 3rd trimester 11.29 (SD 2.01) pmol/l. There were no significant changes in the 1st trimester; 4% and 69% of FT3 results in the 2nd and 3rd trimesters respectively fell below the reference range of mean +/- 2 SD. The corresponding findings for FT4 were 4% and 42%. FT3 correlated reasonably well with total T3 (r = 0.90) and was acceptably precise (within-batch CV 2.1% at 5.6 pmol/l, between-batch CV between 3.1% and 4.7% at six levels).     

Measurement of free thyroxine (T4) levels in pregnancy

Free T4 and TSH were measured in 119 pregnant women. Twenty of these women had the free T4 measured a second time during the pregnancy; 35 of the 119 had the free T4 measured by 2 different methods. The results showed that free T4 fell as pregnancy progressed but even at the early stages of pregnancy many measured free T4 concentrations were below the lower end of the nonpregnant normal range. This remained the case when the measurement was made by a dialysis kit method. These results challenge the current widely-accepted statement that free T4 concentrations remain within the normal nonpregnant range during pregnancy. This study highlights the need for each laboratory to develop its own normal range for free T4 levels in pregnancy.     

Endocrinology of pregnancy. I. Denominations of concentrations of triiodothyronine, thyroxine, effective thyroxine, thyreotrophin and growth hormone in normal pregnancy, labour and in cord blood

Concentrations and activities of the following agents were estimated: triiodothyronine (T3), thyroxine (T4), effective thyroxine (ETR), thyreotrophin (TSH), and growth hormone (HGH). Blood samples were collected in pregnancy, labour and from the umbilical cord of the newborns. It was demonstrated that in normal pregnancy the concentrations of T3, ETR, and TSH did not differ significantly from the values considered as normal in non-pregnant women. The concentration of T4 was distinctly higher in the course of pregnancy (139 to 157 nmol/l versus 110 nmol/l in non-pregnant subjects). The HGH concentration increased during pregnancy from 5.6 to 14.3 micrograms/l. The cord blood demonstrated comparable values of ETR and HGH and in half of the cases of TSH also with those observed in the mothers. In the other one half of the cases, TSH activity was fourtimes higher than the material value. The T3 and T4 were lower than values in the mothers. The results presented are the normal values for further planned investigations of endocrinology of pregnancy, especially for studies into course of pregnancy in women who work in noxious conditions.     

Epilepsy and pregnancy. Serum thyroxine levels during phenytoin therapy.

Blood levels of phenytoin, total thyroxine, and free thyroxine were determined in 10 epileptic women during and following pregnancy. Although total thyroxine concentrations of phenytoin-treated subjects were significantly lower than control values, pregnancy did not appear to diminish the relative increase in total thyroxine seen in normal pregnancy. Free thyroxine concentrations, which were equally depressed at all test times, remained at low euthyroid levels during pregnancy. Following delivery, 3 patients developed free thyroxine levels below 1.0 ng/100 ml. Phenytoin dosage was increased to improve seizure control but produced relatively low blood levels during pregnancy. Following delivery, phenytoin dosage was slightly decreased but produced a significant increase in phenytoin blood levels. The potential effects of phenytoin-related changes in maternal and fetal thyroxine levels are discussed.     

Hormone and enzyme levels in normal and complicated pregnancy

A retrospective study of 48 high-risk pregnancies has been made. The values of two hormonal and two enzyme assays have been compared in assessing placental function. Neither of the enzyme levels (serum heat-stable alkaline phosphatase and serum diamine oxidase) were found to be of clinical value. Serum human placental lactogen levels were consistently decreased in essential hypertension and in pregnancies terminating in stillbirth. Urinary estriol estimation proved to be more reliable, especially in monitoring the “light-for-dates baby” pregnancies and those pregnancies associated with perinatal death.     

Maternal free thyroxine and thyroxine-binding globulin during pregnancy ending in congenital malformations in the offspring

Thyroxine-binding globulin (TBG) and free thyroxine (FT4) were studied in 172 apparently healthy women giving birth to malformed children. The malformations were divided into two groups: minor malformations (group A) and major malformations (group B). The blood samples were usually drawn in the first trimester. Group A showed no significant difference in TBG values compared to women with healthy children. Group B showed lower, but not significantly lower values in earlier pregnancy. However, from the 15th-16th week of pregnancy the TBG values were significantly lower. The FT4 values were in the hyperthyroid range in as much as 20% of the women, compared to the reported rate of 0.2% hyperthyroidism in pregnant women.     

Serum complement levels in normal pregnancy and pregnancy-induced hypertension

Serum complement assay (CH50) was carried out in urban low-income women belonging to the following groups: (i) non-pregnant and non-lactating women; (ii) pregnant women in different periods of gestation; (iii) women suffering from pregnancy-induced hypertension. Serum CH50 titers showed significant increase in the second and third trimester pregnancies as compared to non-pregnant, non-lactating women. There were no differences in CH50 levels between women suffering from pregnancy-induced hypertension and those with normal pregnancy of comparable period of gestation. Nutritional status did not seem to have any influence on complement titers.     

Factor VIII-related antigen levels in normal pregnancy and puerperium

The changes in serum Factor VIII-related antigen (Factor VIII RAg) levels in normal pregnancy and puerperium in Chinese women were studied by the Laurell 'rocket' immunoelectrophoresis. At 6 wk of gestation, the serum Factor VIII RAg levels were already higher than those of non-pregnant women and gradually increased through term pregnancy. Parturition did not have immediate effects on the circulating levels of Factor VIII RAg. The levels of Factor VIII RAg observed during labour and days 1-5 postpartum were similar to those of term pregnancy. By the 6th wk postpartum, the serum Factor VIII RAg declined to basal levels, similar to those of non-pregnant control samples.     

Serum adiponectin levels in normal and hypertensive pregnancy.

OBJECTIVE: The aim of this study was to quantify adiponectin levels in women with normal and hypertensive pregnancies to determine whether there is an independent association, while controlling for body fat and insulin sensitivity. METHODS: A cross-sectional study was conducted in the following categories: 12 normotensive non-pregnant women, 10 normotensive, 12 gestational hypertensive, 13 essential hypertensive, and 12 preeclamptic women. All subjects underwent measurements of body fat by bio-impedance analysis and blood sampling. RESULTS: Percentage of body fat and insulin resistance were greater in all pregnant groups compared with non-pregnant women. Adiponectin concentrations were significantly lower in women with normal pregnancies (18.6 +/- 1.4 microg/mL, p = 0.02) compared with non-pregnant women (24.0 +/- 1.5 microg/mL). However, adiponectin levels were not significantly different among normal pregnancy, gestational hypertension (19.0 +/- 3.1 microg/mL), essential hypertension (24.0 +/- 3.7 microg/mL) and pre-eclampsia (22.4 +/- 2.5 microg/mL) groups. Adiponectin levels were inversely related to percent body fat and insulin resistance. When adiponectin levels were corrected for percent body fat and insulin resistance, no significant differences were seen among the study groups. CONCLUSIONS: Adiponectin levels are decreased in normal pregnancy, however this difference disappears when adiponectin levels are corrected for the pregnancy-related increases in body fat and insulin resistance. Adiponectin levels are not altered significantly in states of hypertension in pregnancy compared with normal pregnancy.     

Glutathione peroxidase levels throughout normal pregnancy and in pre-eclampsia

Objective: Evidence suggests that hemoglobin, in addition to its function as a carrier of oxygen, also serves to transport nitric oxide, as S-nitroso cysteine, from the lungs to the peripheral circulation, where it can be released. Glutathione peroxidase, besides being an important antioxidant, is known to catalyze the release of nitric oxide from smaller carrier molecules, and may play a role in the distribution of nitric oxide throughout the body. In light of these findings, we sought to determine whether glutathione peroxidase levels differed throughout gestation, and specifically between pre-eclamptic and normal women. Methods: A nested case-control study of women receiving routine prenatal care was conducted. Pre-eclampsia was defined by a blood pressure of at least 140 mmHg systolic and/or 90 mmHg diastolic as well as proteinuria > 300 mg/24 h or > 2+ by dipstick, both occurring on two occasions at least 6 h apart. Blood was collected in heparinized tubes and was then centrifuged in a clinical centrifuge for 10 min. Plasma was frozen promptly at -80°C for later enzyme-linked immunosorbent assay (ELISA), with which plasma glutathione peroxidase was determined. Results: The maternal demographics of the pre-eclamptic and non-pre-eclamptic study groups did not significantly vary with respect to mean maternal age, gravidity, parity and gestational age at the time of delivery. The median maternal ages were 33 and 34 years, and the median gestational ages at the time of birth were 37.5 and 38.1 weeks, respectively. In evaluating the glutathione peroxidase levels of all patients across the three trimesters, we found that there was essentially no difference in mean levels (83.7, 81.0 and 89.5 ng/ml, respectively). There was no difference between the pre-eclamptic and non-pre-eclamptic patients, again stratified by trimester. A linear regression analysis indicated that the plasma glutathione peroxidase concentration did not correlate with gestational age or the presence of pre-eclampsia. Conclusions: Plasma glutathione peroxidase expression is similar across all trimesters. There is no change in the glutathione peroxidase levels in pre-eclamptic patients.     

Adrenomedullin levels in normal and preeclamptic pregnancy at term

OBJECTIVE: To describe maternal plasma levels of adrenomedullin (AM), a hypotensive and natriuretic peptide, in normal and preeclamptic women at term. STUDY DESIGN: Maternal plasma AM levels were determined in 13 preeclamptic and 15 normotensive primigravidas by radioimmunoassay. Plasma samples were obtained with the patients in the lateral recumbent position before the administration of any medications. RESULTS: Women with preeclampsia had significantly elevated AM levels when compared with normotensive controls (42.3 +/- 10.5 pg/mL versus 16.9 +/- 3.1 pg/mL, P < .011). CONCLUSION: In this pilot study, AM levels were significantly increased at term in preeclamptic women.     

Fetal and maternal erythropoietin levels in normal pregnancy.

In a cross-sectional study of 120 pregnancies undergoing cordocentesis for prenatal diagnosis (n = 90) or elective caesarean section (n = 30), the umbilical cord and maternal venous plasma erythropoietin (Epo) concentrations were measured. Fetal Epo levels increased from a mean of 4 mU/ml at 16 weeks to 13 mU/ml at 40 weeks' gestation. There were no significant associations between fetal plasma Epo concentration and fetal blood gases, haemoglobin concentration, oxygen content or erythroblast count. The maternal plasma Epo concentration (mean = 14 mU/ml, range 1-77 mU/ml) did not change with gestation but was significantly higher than levels in non-pregnant females (mean = 6.6 mU/ml, range 1-25 mU/ml).     

Regulation of plasma adenosine levels in normal pregnancy

The aim of this study was to investigate the possible mechanism of the regulation of plasma adenosine concentration [ADO] in normal pregnancy. We measured the activities of circulating enzymes that are involved in the production and metabolism of adenosine, and plasma [ADO] in nonpregnant (n = 14) and normal pregnant women (n = 14) in the third trimester. In pregnant women, the activity of plasma 5'-nucleotidase and plasma [ADO] were significantly elevated and plasma adenosine deaminase activity was significantly reduced. Enzymatic activities of both plasma enzymes appear to be changed in a way that would favor increased adenosine concentrations.