Comparison of progesterone concentration determination by 12 non-isotopic immunoassays and gas chromatography/mass spectrometry in 99 human serum samples.

A single serum progesterone determination may be highly predictive for early pregnancy and in vitro fertilisation and embryo-transfer outcomes. We therefore compared 12 direct non-isotopic progesterone immunoassays with gas-chromatography/mass spectrometry (GC/MS). For each assay, data from the analysis of 99 individual sera were compared with data obtained by GC/MS, using regression and bias plot analyses and the ratio method. We observed a larger difference in concentration between high and low values and a broader distribution of results for immunoassays than for GC/MS. All immunoassays displayed bias in the calibration process and a lack of specificity and/or sensitivity, to various degrees. We tried to identify the parameters of the assay procedure that might contribute to these discrepancies. None of the criteria investigated (antibodies, control and preparation of calibrators, blocking agents and choice of tracer) had a significant effect when studied alone.

Early detection of antibodies to human immunodeficiency virus 1 by a third-generation enzyme immunoassay. A comparative study with the results of second-generation immunoassays and western blot.

The aim of the study was to examine the sensitivity and the specificity of a HIV-1/HIV-2 third-generation enzyme immunoassay, the Abbott recombinant HIV-1/HIV-2 third-generation enzyme immunoassay, which is reported to detect simultaneously IgG and IgM. Sensitivity was evaluated with sera from seropositive subjects and a series of samples from eight HIV-1 seroconverting subjects. Results were compared with Western blot, second-generation immunoassays (including Vidas HIV-1 + 2) and an HIV-1 antigen assay. Specificity was studied with sera collected from a low-risk population and sera with false-reactive enzyme immunoassays results. In seven cases, the third-generation immunoassay detected HIV-antibodies several days earlier (range 4 to > or = 9 days) than the Western blot test according to the criteria proposed by the Association of State and Territorial Public Health Laboratory Directors, ie, positive with two of the three bands-gp160 or gp120, gp41, and p24. In the last case detection occurred at the same time as Western blot. The second-generation tests generally detected HIV-antibodies at the same time as Western blot. Antigaenemia was positive in the first samples tested in most cases, prior to or simultaneously with the Abbott third-generation test first reactivity, before the second generation tests and the Western blot test. In most cases, the disappearance of detectable HIV antigen was observed, and was concurrent with the development of the antibodies immune response. For our low-risk population, the current third-generation EIA test obtained a false-reactive rate of 0.26%. Our data indicate that the Abbott third-generation immunoassay is more sensitive than the Western blot test and the second-generation tests. The addition of a third-generation assay to the strategy for HIV-antibody screening may indeed be of interest and could make it possible to decrease the number of false-negative results.

[Laboratory follow-up in menopause]. / Suivi biologique de la ménopause.

Menopause is not an illness. Nevertheless, nowadays, it is medically approached. We know now with precision the consequences of the estrogen deficiency on about fifty woman's wellbeing, on her metabolism, her cardiovascular system, her bones. A substitutive hormonal therapy is more and more often proposed in order to correct the immediate functional disorders and to prevent the long term consequences (cardiovascular diseases and osteoporosis especially). What is the place of biology in the follow-up of a menopausal patient? Even if clinic observation is predominant for the diagnosis of menopause, plasmatic FSH and estradiol assays are of precious aid in particular cases (hysterectomised patients for example). Whether or not we consider a substitutive hormonotherapy, menopause installation is a good opportunity for detection of metabolic diseases, beginning often in this part of life or clinically suspected. Before beginning a substitutive treatment, biological assays contribute to define the patients's metabolic profile in order to adjust the choice between oral or percutaneous estrogenotherapy and to detect contra-indications. The biological markers of osteoporosis risk are objective arguments to incite indecisive women for beginning or for continuation of a treatment. Under hormonotherapy, plasmatic estradiol's assay should aid to confirm the correct adequation of substitutive doses, but in practice it is not much used: clinical examination is generally adequate to detect under or over dosage. In post-menopause, wether or not she receive a substitutive hormonal therapy, every women should have the benefit of a regular biological follow-up, in the same way as a mammography and cervical smears are recommended. Age being by oneself the main factor for metabolic risk, early detection and early correction of abnormalities will be the main part to ensure quality, for women and also for men, of the second half time of their life.

[Pregnancy and perinatality: biological follow-up]. / Grossesse et périnatalité: suivi biologique.

Blood and urinary tests which are necessary for pregnancy diagnosis and follow-up, for newborn and mother medical supervision, during the month following birthday, are today described in reglementary texts, laws, and recommendations such as advised medical references (RMO). These documents specify the nature of obligatory tests, the checking rhythm and the list of useless tests. hCG research remains necessary for pregnancy diagnosis, but hCG dosage is essential only in case of programmed medical assistance or pathological pregnancy (extrauterine pregnancy, hydatiform mole, choriocarcinoma). The obligatory follow-up of a pregnant woman includes determination of blood groups, research of infectious agents responsible for diseases (toxoplasmosis, rubeola, hepatitis B, syphilis), proteinuria and glycosuria research and blood count according to a given calendar. When the mother's condition is bad and reminiscent of a pathological pregnancy, when a genetic risk exists for the fetus or when fetal growth is abnormal as indicated by echographic control (intra-uterine growth retardation), laboratory tests are used to follow the maternal pathological course (arterial hypertension, diabetes mellitus, anemia, bacterial, viral or parasitic disease), to verify the existence of a genetic disease, to know about the fetal functional state (by amniocentesis or cordocentesis), to identify an erythrocyte fetomaternal incompatibility. Since last trimester pregnancy accidents are able to endanger mother's and fetus lives, the feto-maternal follow-up must be adjusted to pathological diagnosis types and requires a particular supervision of the delivery. Finally mother and child must undergo a post-natal follow-up during the four weeks after birthday (perinatality control).

[Immunological assay of chorionic gonadotropin during pregnancy. Multicenter study of 5 reagents]. / Dosage immunologique de l'hormone gonadotrope chorionique au cours de la grossesse. Etude multicentrique de cinq réactifs.

Five commercial kits for the quantitative determination of human chorionic gonadotropin (hCG) used for detection and monitoring of pregnancy were evaluated. Five kits used two-sites "sandwich" enzymoimmunoassay and monoclonal antibodies. Precision, standardization and sensitivity were tested and practicability was assessed. Good results are obtained for four kits (Beckman had poor results), sensitivity and specificity are good. Practicability of five kits was evaluated but choose was in relation to configuration of laboratory.

[Value of immunoassay of hCG for the determination of high plasma concentrations]. / Validité des immunodosages de l'hCG appliqués à la détermination de concentrations plasmatiques élevées.

The serum concentration of human chorionic gonadotrophin is higher in trisomy 21 than in normal pregnancy. Our study aimed at comparing 17 commercial kits, both those for measuring high concentrations and others for diagnosis and initial follow-up of pregnancy under specific conditions, ie for measuring hCG concentrations between weeks 14 and 18 of pregnancy. All kits were satisfactory; however, usual values for the gestational weeks concerned need to be established for each reagent.

[Validity of immunochemical assays for blood estradiol. Study conducted in 1994]. / Validité des dosages immunochimiques de l'estradiol sanguin. Etude réalisée en 1994.

Since 1989 many kits have been commercialized for measuring estradiol by non-isotopic immunoassays which largely contributed to the diffusion of this parameter. Rapidly, in quality control schemes, a wide dispersion of results has been observed. In this paper, the kits' characteristics (precision, accuracy and detection limit) have been studied and compared to a reference method (gas chromatography-mass spectrometry). In addition, estradiol determinations in patients with various pathophysiological situations have been performed to underline the difficulties of interpretation of this analyte when clinicians compare results given by the different kits. This work demonstrates that precision and accuracy varied both with the kit and the level of concentration of estradiol and gives better results for high concentrations of estradiol. In seven out of the 12 kits, the limits of detection are in good agreement with those announced by manufacturers. On the contrary, the determination on patients sera gives results with a high variability with no systematic error.

[Immunoassay and measurement of the biological activity of serum hLH: results obtained of a multicenter study]. / Immunodosages et mesure de l'activité biologique de l'hLH sérique: résultats obtenus lors d'une étude multicentrique.

The discrepancy between results obtained using different anti-hLH antibodies available on the market led us (in the context of a contract with the CNAMTS) to compare the results of hLH immunoassays (eight different reagents) with those of hLH bioassays based on the measurement of the steroidal activity of this hormone on mouse, rat or pig testicular preparations (five methodologies). Twenty-nine samples of serum or human serum pools were tested. The values resulting from these tests reveal differences linked to the nature of the antibodies or to the methodological conditions used for the testicular preparations. Some antibodies seem unable to identify some hLH forms which, however, can be detected by biological methods.

[Validity of immunochemical methods for bloody progesterone: a study performed in 1998]. / Validité des dosages immunochimiques de la progestérone dans le sang: étude réalisée en 1998.

The aim of this study was to compare, with manufacturer's agreement, twelve direct and non-isotopic commercial assays of progesterone. We have evaluated the analytical performances: low limit detection, imprecision, accuracy (recovery and dilution tests) and we have tested some patient samples. Results were compared to a reference method using isotope dilution Gas Chromatography and Mass Spectrometry combination (GC-MS). For each assay, analytical qualities and defaults are established. Large differences are found between progesterone concentration measured on the same sample with the different methods essentially for the low concentrations. Comparison with GC-MS raised questions about the accuracy of the different assays. This work will be aid laboratories to their choice and/or validation.

[Comparative study of ofloxacin+amoxicillin-clavulanic acid versus doxycycline+amoxicillin-clavulanic acid combination in the treatment of pelvic Chlamydia trachomatis infections]. / Etude comparative des associations ofloxacine+amoxicilline-acide clavulanique versus doxycycline+amoxicilline-acide clavulanique dans le traitement des infections génitales hautes à Chlamydia trachomatis.

OBJECTIVE: To evaluate the efficacy and safety of ofloxacin+coamoxiclav versus doxycycline-coamoxiclav in the treatment of chlamydial pelvic infections. DESIGN: An open, comparative, randomised, monocentric study. SUBJECTS: A hundred and eighteen patients (85 endometritis and 33 salpingitis) were included. Clinical, laparoscopic and bacteriological assessments were performed before treatment. 30.4% of salpingitis were considered as severe (COGIT score > 6). 25.4% of acute pelvic infections were only caused by Chlamydia trachomatis. TREATMENT: A hundred and eighteen patients were treated orally with 3 week combination ofloxacin (200 mg b.i.d.) + coamoxiclav (1 g b.i.d.) (n = 60) or with a 6 week coamoxiclav (1 g b.i.d.) + doxycycline (100 mg b.i.d.) (n = 58). RESULTS: Oral combination ofloxacin-coamoxiclav is as effective as oral combination doxycycline+coamoxyclav with respectively 96.7% versus 96.6% and 100% versus 98.4% satisfactory clinical et bacteriological results.

[Quantitation of hCG. Decision boundary and clinical decision threshold]. / Dosage d'hCG. Limite de décision et seuil de décision clinique.

The clinical decision threshold is defined by the level required to establish the presence of hCG and to measure the quantity. It is different from detection limit because it does not result from a calculation with an error risk but it is experimentally determined.

[The choice between theophylline and caffeine in the treatment of apnea in premature infants]. / Le choix entre théophylline et caféine dans le traitement des apnées du prématuré.

In a double blind study, two comparable groups (each n = 10) of premature infants less than 34 weeks of gestational age, with idiopathic apnea were given an IV treatment of either theophylline or caffeine. The loading doses were respectively 6 and 10 mg/kg and the maintenance doses were 2 and 1.25 mg/kg every 12 hours. In both groups, apneas greater than or equal to 15 s. with or without bradycardia were similarly reduced (p less than 0.01). Both drugs increased significantly the respiratory rate. Compared to caffeine, theophylline induced a significant acceleration of heart rates, an increase in urinary sodium excretion, more frequent gastrointestinal intolerance and behavioral changes. Plasma concentrations of theophylline were less stable than those of caffeine. These data suggest that a single daily dose of caffeine should be preferentially used in the treatment of idiopathic apneas of prematurity.

Undetectable luteinizing hormone levels using a monoclonal immunometric assay.

Previous studies have shown wide discrepancies among the results obtained with different immunometric assays. We present five cases (out of 4000 women) whose plasma luteinizing hormone was not detected using a LH immunometric assay (LH Stratus Baxter) but was recognized by other kits. These cases concerned one 28-year-old woman presenting with infertility and four postmenopausal women. The LH Amerlite kit gave detectable but low results. The results obtained with the other kits were > 7 IU/l. FSH levels were > 7 IU/l. In one case, sera were taken before and after the menopause; differences between the LH results increased. Discrepancies among LH assay kits have been attributed to variation both in standard curve calibration and in epitope specificity of the kit monoclonal antibodies. The Baxter kit might misrecognize some isoforms present in postmenopausal women. The present data illustrate the potential false results with such immunoassays in routine clinical laboratory testing. When undetectable LH results are not clinically explained or when disparities between LH and FSH are observed, we suggest using a second methodology or a bioassay if necessary. Improvement in LH assays and standardization might resolve the problem of discrepancies between the LH results.

Inhibin as a marker for hydatidiform mole: a comparative study with the determinations of intact human chorionic gonadotrophin and its free beta-subunit.

OBJECTIVE: The purpose of the study was to evaluate plasma inhibin as a marker of hydatidiform mole and to compare the results with intact human chorionic gonadotrophin (hCG) and its free beta-subunit. DESIGN: Serial determinations of the plasma concentrations of inhibin, intact human chorionic gonadotrophin and its free beta-subunit in cases of hydatidiform mole over an average period of 140 days. PATIENTS: Five cases of hydatidiform mole, including patients with spontaneous remission after evacuation or persistent trophoblastic disease. MEASUREMENTS: Immunoreactive inhibin, hCG and free hCG beta-subunit were measured using standard enzyme immunoassays. RESULTS: Inhibin and free hCG beta-subunit levels were greater than in normal pregnant women at the same gestational age. Only intact hCG could detect the persistence of trophoblastic tissue. CONCLUSIONS: Our data suggest that inhibin, intact human chorionic gonadotrophin and free beta-subunit might be useful as diagnostic markers of molar pregnancies. However, the original method of intact hCG determination is still superior for follow-up.

Severe side effects and drug plasma concentrations in preterm infants treated with doxapram.

A high-performance liquid chromatography method has been developed for simultaneous determination of doxapram and its metabolites including ketodoxapram, the main and only active metabolite. The aim of the study was to evaluate this microtechnique and to report the cases involving severe adverse effects to determine toxic plasma levels in neonates. The method was found to be selective, and showed a good baseline separation of doxapram and metabolites. Recovery, linearity, intraday/interday precision, and limit of detection determined in aqueous solutions and in spiked plasma were satisfactory. The assay is simple, rapid, and plasma-sparing, which represents a true advantage in managing neonates. Case analysis was performed in two consecutive periods: 124 preterm infants in the first period and 173 in the second period. Severe toxic effects were observed in 4 cases in the first period, with doxapram plus keto-doxapram levels 9 mg/L. In the second period, only one case was observed. High-range plasma concentrations were significantly less frequent in the second period than in the first one. The authors conclude that measuring doxapram plus keto-doxapram in plasma may be of interest to avoid severe toxic effects in preterm neonates treated with doxapram.