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Jingya Zhou, Meng Zhang, Lin Lu, Xiaopeng Guo, Lu Gao, Weigang Yan, Haiyu Pang, Yi Wang and Bing Xing

addition, several studies have demonstrated that there are always some potential sources of error interposed between the clinician’s diagnosis and the nosological diagnosis code assigned by the clinical coder ( 12 , 13 ). To date, studies on the validity

Open access

M P Schuijt, C G J Sweep, R van der Steen, A J Olthaar, N M M L Stikkelbroeck, H A Ross and A E van Herwaarden


Increased maternal testosterone concentration during pregnancy may affect the fetus. Therefore it is clinically relevant to have a quick and reliable method to determine free testosterone levels. Current calculators for free testosterone are suspected to perform poorly during pregnancy due to suggested competition between high levels of estradiol and free (bio-active) testosterone for sex hormone-binding globulin (SHBG) binding. Therefore, it is claimed that reliable calculation of free testosterone concentration is not possible. However, recent evidence on SHBG-binding sites questions the estradiol effect on the testosterone-SHBG binding during pregnancy. In this study, we investigated whether the free testosterone concentration can be calculated in pregnant women.

Design and methods

Free testosterone was measured with a specially developed equilibrium dialysis method combined with liquid chromatography tandem mass spectrometry (LC-MS/MS). Free testosterone was also calculated with the formulas of Vermeulen et al. and Ross et al.


Total and free testosterone measured in healthy men and women were in good agreement with earlier reports. In pregnant women, total testosterone values were higher than in non-pregnant women, whereas free testosterone values were comparable. Calculated free testosterone levels in pregnant women were highly correlated, but marginally higher, compared to measured free testosterone levels.


We developed an equilibrium dialysis–LC-MS/MS method for the measurement of free testosterone in the low range of pregnant and non-pregnant women. Although during pregnancy total testosterone is increased, this is not the case for free testosterone. The free testosterone formulas perform well in pregnant women.

Open access

Marieke Stientje Velema, Aline de Nooijer, Ad R M M Hermus, Henri J L M Timmers, Jacques W M Lenders, Olga Husson and Jaap Deinum

confirm the scale structure found in exploratory factor analysis. We examined for item-scale convergent validity, corrected for overlap. We tested item-scale discriminant validity by comparing the correlation of each item with its own scale versus the

Open access

Marieke S Velema, Evie J M Linssen, Ad R M M Hermus, Hans J M M Groenewoud, Gert-Jan van der Wilt, Antonius E van Herwaarden, Jacques W M Lenders, Henri J L M Timmers and Jaap Deinum

renin concentration. Internal validation of the model We applied bootstrapping techniques to estimate overoptimism and to assess internal validity ( 14 , 15 ). Random bootstrap samples with replacement were drawn from the whole database

Open access

Nidan Qiao

quality assessment ( Table 1 ) of each study consists of five categories: unmet need (limits in current non-machine-learning approach), reproducibility (feature engineering methods, platforms/packages, hyperparameters), robustness (valid methods to

Open access

Jes Sloth Mathiesen, Jens Peter Kroustrup, Peter Vestergaard, Per Løgstrup Poulsen, Åse Krogh Rasmussen, Ulla Feldt-Rasmussen, Sten Schytte, Stefano Christian Londero, Henrik Baymler Pedersen, Christoffer Holst Hahn, Jens Bentzen, Sören Möller, Mette Gaustadnes, Maria Rossing, Finn Cilius Nielsen, Kim Brixen, Christian Godballe and Danish Thyroid Cancer Group (DATHYRCA)

-based studies securing external validity are needed. Declaration of interest The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported. Funding This work was

Open access

Maxime Duval, Kalyane Bach-Ngohou, Damien Masson, Camille Guimard, Philippe Le Conte and David Trewick

, ventricular tachycardia and VF, with hypocalcemia ( 13 ). However, these case reports often attribute the rhythm change to hypocalcemia when a perfectly valid differential diagnosis is present. For instance, Gmehlin et al . reported a case of VF attributed to

Open access

Lijin Ji, Na Yi, Qi Zhang, Shuo Zhang, Xiaoxia Liu, Hongli Shi and Bin Lu

statistically significant. Results Questionnaire collection A total of 720 questionnaires were distributed. We received a total of 290 valid questionnaires, and the questionnaire response rate was 40%. General information The ratio of male

Open access

A C Paepegaey, M Coupaye, A Jaziri, F Ménesguen, B Dubern, M Polak, J M Oppert, M Tauber, G Pinto and C Poitou

or had a measurement of cortisol level at 08:00 h. However, only 37.9% had a valid screening for the corticotropic axis, defined as performing a dynamic test if the cortisol level at 08:00 h was between 138 and 500 nmol/L. There was no difference

Open access

Mubashir Mulla and Klaus-Martin Schulte

and conclusions from the 21 studies are incorrect. Table 4 Study details and validity: central and combined cervical LN. Study Patients included Study hypothesis TP TN FP FN Sen Spec PPV NPV Validity of conclusion Central   (31) 28 To determine the