[Congenital toxoplasmosis due to maternal reinfection during pregnancy]. / Toxoplasmose congénitale secondaire à une réinfection maternelle pendant la grossesse.

Reinfection with Toxoplasma gondii is exceptional but can lead to transmission to the fetus when it occurs during pregnancy. We present a case of congenital toxoplasmosis in a young baby born to an immunocompetent mother who had been immunized against toxoplasmosis before pregnancy. The presence of residual IgG-specific antibodies does not always mean an absolute protection against a new toxoplasma infection. During the pregnancy, the patient was advised to follow the hygienic and dietary preventive measures even though the previous test results were consistent with past toxoplasma infection.

[Difficulties of interpretation in toxoplasma serology in a pregnant woman in the context of a maternofetal alloimmunization against HPA-1a platelet antigen]. / A propos d'un cas de sérologie toxoplasmique chez une patiente enceinte dans un contexte d'allo-immunisation foetomaternelle anti-HPA-1a.

Serological status in case of Toxoplasma gondii infection needs to be established either before or at the beginning of a pregnancy. However, clinical biologists are often facing conflicting serological results that are difficult to interpret: we report here the case of a woman in her 30th week of pregnancy. Both her IgM and IgG were negative at the 14th week of pregnancy; but suddenly, starting from the 20th week, her IgG became positive while her IgM remained negative. We remind here of the most frequent hypothesis that can explain a sudden and isolated increase of anti-T. gondii IgG: Is it a technical problem (specificity)? Is it a drug interference? Eventually, we found that the patient was receiving, since the 16th week of pregnancy, every week an intravenous perfusion of polyvalent immunoglobulins. Since we didn't know if the IgG present in this perfusion can protect the patient against toxoplasmosis, we decided to consider this women as non immune.

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.