Graham D. Carter

Investigation of Hirsutism: Testosterone is Not Enough:

SUMMARY In a consecutive series of 41 hirsute women clinically classified as benign androgen excess, only 34% were found to have elevated plasma ‘total’ testosterone (T), 22% having subnormal sex hormone binding globulin (SHBG). When expressed as the ratio T/SHBG (‘free androgen index’), 85% of the patients had values above the normal range. It is concluded that this index is more reliable than total testosterone in assessing androgen status in female patients.

25-Hydroxyvitamin D: A Difficult Analyte

In their article in the current issue of Clinical Chemistry , Farrell et al. (1) describe the latest in a number of studies (2, 3) highlighting the method-related variability in serum 25-hydroxyvitamin D (25-OHD)2 results. There is common agreement that 25-OHD is a “difficult” analyte. That quality is generally ascribed to its hydrophobic nature, its existence in several different molecular forms, its tight binding to vitamin D– binding protein (VDBP) and, until recently, the absence of reference materials or a reference measurement procedure (RMP) against which assays could be standardized. This last problem was mitigated to some extent with the introduction in 2009 of the NIST Standard Reference Materials (SRM 972 and SRM 2972) and the acceptance of the NIST and University of Ghent liquid chromatography–tandem mass spectrometry (LC-MS/MS) assays as RMPs (4). Unfortunately, 3 of the 4 SRM 972 reference materials are either spiked with exogenous metabolites or diluted with equine serum, characteristics that render these reference materials unsuitable for many immunoassays (5, 6). The history of 25-OHD methodology could serve as a case study of the consequences of transferring a rigorous but labor-intensive method from the unhurried atmosphere of the research laboratory to the bustle of a routine clinical laboratory having to meet tight deadlines. The pioneering competitive protein-binding (CPB) method of Haddad and Chyu (7) involved solvent extraction and chromatography, with the results of every sample corrected for procedural losses. Subsequent attempts at simplifying a CPB method by omitting the chromatography stage proved unsuccessful (8), and an automated version (Nichols Advantage) introduced in 2004 was withdrawn in 2006. The successive abandonment of sample extraction, chromatography, and correction for procedural losses in immunoassays has undoubtedly contributed to the inconsistencies reported by Farrell et al., as have differences in assay standardization. Nevertheless, results submitted to …

25-Hydroxyvitamin D Assays: The Quest For Accuracy

The recently reported difficulties experienced by Quest Laboratories (1) have once again highlighted concerns about the reliability of 25-hydroxyvitamin D (25-OH-D)1 results, particularly those generated by liquid chromatography–tandem mass spectrometry (LC-MS/MS), the method used by Quest. In the New York Times article of January 8, 2009 (1), a spokesman for Quest admitted that some erroneous results were reported because of problems with calibration and that some of their laboratories “did not always follow proper procedures.” One suspects these shortcomings were influenced by the eye-watering number of 25-OH-D requests received by Quest: 500 000 per month according to John Cannell, quoted in a pathologist’s newsletter (2). This unfortunate episode dramatically emphasizes the need for a rigorous internal quality-assurance system. Such a system must include a role for a quality manager (preferably independent) who should be responsible for the monitoring of internal quality controls and the results of external proficiency-testing schemes. Some of us learned of the Quest problem through John Cannell’s Vitamin D Council newsletter sent out in July 2008 (3). In the same issue, he was promoting, without apparent irony, a commercial kit designed to “accurately” measure 25-OH-D in patient-generated blood spots, a technique that cannot easily be monitored by external proficiency-testing schemes. Those of us who work in clinical laboratories know that “stuff happens.” At some stage in our careers, many of us will probably have to contact clinical colleagues to admit reporting errors of some sort, although almost certainly not on the scale reported in the New York Times . It is to Quest’s credit that they admitted the problem and offered to repeat these analyses free of charge. It is important that the publicity given to Quest’s problems not lead to LC-MS/MS being regarded as an inherently unreliable technique. The introduction of LC-MS/MS represents …

A COMPARISON OF FOLLICULAR FLUID LEVELS OF INSULIN‐LIKE GROWTH FACTOR‐1 IN NORMAL DOMINANT AND COHORT FOLLICLES, POLYCYSTIC AND MULTICYSTIC OVARIES

Fourteen ovulatory patients undergoing diagnostic laparoscopy had at least two samples of clear follicular fluid (FF) collected in the late follicular phase. The cohort concentrations of Insulin‐like Growth Factor‐1 (IGF1) were significantly correlated with serum IGF1 and dominant follicles contained significantly higher concentrations of IGF1 and oestradiol (E2) than their cohorts. After the LH surge, a further significant increase in dominant FF‐IGF1 occurred. FF‐(log)E2 was significantly correlated with both FF‐IGF1 and FF volume. Nine women with the polycystic ovary syndrome (PCOS) and one patient with multicystic ovaries (MCO) associated with weight‐loss related amenorrhoea also had follicular aspiration performed. The mean (SD) FF‐IGF1 in the PCOS group, 0.42 (0.15) U/ml, was not significantly different from that of the cohorts in the control group, 0.39 (0.13) U/ml. The patient with MCO had both serum and FF‐IGF1 concentrations < 10th centile. These results support the hypothesis that IGF1 has a paracrine (and possibly endocrine) role in the regulation of ovarian function in the human female.

Troponin T for the Differential Diagnosis of Ischaemic Myocardial Damage

The diagnostic performance of a new enzyme linked immunosorbent assay for the cardiac structural protein troponin T in the differential diagnosis of ischaemic cardiac damage was assessed. A well documented set of patients admitted to the coronary care unit of a district general hospital were studied. At a cutoff value of 0·2μ/L, troponin T measurements 12–24 h after admission or 12–16 to 24–48 h from onset of chest pain showed an overall efficiency of 97 · 6% for diagnosis of proven myocardial infarction. Troponin T was not detectable in patients when ischaemic heart disease could be excluded but was present in four patients with angina. Detectable troponin T in these angina patients was associated with subsequent cardiac events.

Oestradiol assays: applications and guidelines for the provision of a clinical biochemistry service.

This paper reports on the provision of a clinical biochemistry service for serum oestradiol. The pathophysiology and recognised applications of oestradiol assays are discussed and the current availability of assay reagents and methodologies reviewed. Data are presented on the analytical performance of assays for serum oestradiol in the UK External Quality Assessment Scheme (UKEQAS) and general guidance is offered to laboratories providing a diagnostic service for this analyte.

Contemporary Diagnosis and Treatment of Vitamin D-Related Disorders

Plasma 25(OH)D has emerged as a valuable biomarker for the many varied health‐related effects of vitamin D in the clinic mainly because of the recognition of the importance of the enzyme, CYP27B1, or the 25(OH)D‐α‐hydroxylase in the extrarenal, target cell production of calcitriol. This review briefly assesses current methodology for plasma 25(OH)D assay focusing mainly on currrent controversies surrounding the definition of the normal range and performance characteristics of the assay, separate measurement of both 25(OH)D2 and 25(OH)D3, and quality assurance tesing of laboratories offering the test. Clinicians have two main types of 25(OH)D assay based on either high‐performance liquid chromatography with UV or mass detection or higher throughput kits based on protein (competitive protein binding assay or radioimmunoassay) binding. Based on 30 yr of experience with measuring 25(OH)D levels, it is concluded that, in the hands of appropriately trained experts, both types of assay provide reliable and accurate results, but all laboratories providing 25(OH)D data need frequent external quality assurance service to ensure that this performance is maintained.

Changes in bone density and biochemical markers of bone turnover in pregnancy‐associated osteoporosis

* Gautam Khastgir Research Fellow (Wellbeing Grant), * John W. W. Studd Consultant Gynaecologist, * Hilary King Senior Radiographer, * Hossam Abdaila Consultant Gynaecologist, ** Julia Jones Senior Scientist, ** Graham Carter Consultant Biochemist, ** Jamshid Alaghband-Zadeh Consultant Endocrinologist * Fertility and Endocrinology Centre, Lister Hospital and Academic Department of Obstetrics and Gynaecology, Chelsea & Westminster Hospital, London ; ** Endocrine Laboratory, Charing Cross Hospital, London

A study to evaluate serum and urinary hormone levels following short and long term administration of two regimens of progesterone cream in postmenopausal women

Objective To determine the pharmacokinetics of a progesterone cream following short and long term dermal administration.

IS THE POLYCYSTIC OVARY A CAUSE OF INFERTILITY IN THE OVULATORY WOMAN

Ovulatory women with polycystic ovaries (PCO) were compared with ovulatory women with normal ovaries, using high‐resolution ultrasound and biochemical parameters to compare precise points in the menstrual cycle taking the day of ovulation as day 0. The PCO group had higher median follicular phase LH (days ‘menses’, −5, −3), FSH (days −5, −3) testosterone (days −3, −2) and free androgen index (days −5, −3, −1) than the controls. Women with PCO had a longer follicular phase and larger follicles. These results suggest that abnormal secretion of LH and free testosterone may contribute to the subfertility of women with PCO, possibly by premature activation of the oocyte or by interfering with folliculogenesis.