Improved performance of plasma gonadotrophin assays using common reagents and assay protocols: evidence from the UK External Quality Assessment Scheme

Progress and problems in immunoassays for serum pituitary gonadotrophins: evidence from the UK external quality assessment schemes, (EQAS) 1980-1988

Trends in the quality of assays for serum gonadotrophins performed by laboratories in the UK EQAS during the 1980s are reviewed, with particular reference to the effects of the recent introduction of immunometric assays (IMA) as an alternative to radioimmunoassay (RIA). IMA gave results which were on average 17% higher than RIA for FSH, and 33% lower for LH. These bias characteristics were not entirely accounted for by differences in assay standardisation, but appeared to reflect the different isoforms of the hormones detected by the monoclonal antibodies used in the IMA. Between-laboratory agreement remained, consequently, unsatisfactory overall (geometric coefficient of variation, GCV, 20-30%), although good within method groups (GCV 10%). IMA were less vulnerable to non-specific background interference than many RIA, and could avoid interference from HCG. Some IMA were, however, vulnerable to interference from heterophilic antibodies in patients' sera. The differences between RIA and the various IMA in numerical values reported, and in their vulnerability to interferences underline the need for care in interpreting assay results.

The role of the laboratory in the investigation of infertility

The incidence and the causes of the various types of infertility in men and women are described. Accurate diagnosis of the cause or causes of a couple's infertility is important as the treatment is often expensive and lengthy. A thorough clinical investigation of the couple will indicate which laboratory tests to embark upon. Endocrine abnormalities may account for about a third of diagnoses in women but are rare in men. Standard immunoassay procedures are used for hormone assays to diagnose endocrinopathies and should be performed in a logical sequence. They help to identify hyperprolactinaemia and to distinguish primary gonadal failure from lesions of the hypothalamic-pituitary axis. The common drugs available for treatment are listed and guidelines are given on management during treatment. Hormone assays are useful, but ultrasonic scanning is efficient and rapid and is becoming the preferred method for monitoring follicular growth.

Assays for follicle stimulating hormone and luteinising hormone: guidelines for the provision of a clinical biochemistry service

The measurement of serum follicle stimulating hormone (FSH) and luteinising hormone (LH), together with the appropriate sex steroid, is of great value in the investigation of delayed and precocious puberty, hypogonadism, subfertility, polycystic ovarian disease and hypothalamic-pituitary disorders. Dynamic function testing of the hypothalamic-pituitary-gonadal axis should be restricted to a few defined situations. Sequential LH measurements, either in serum or in urine, may be used to time ovulation during artificial insemination or in vitro fertilisation programmes. No special precautions are necessary when sampling for FSH and LH measurement; serum is preferred to plasma and should be stored frozen before assay. Aliquots of timed urine specimens of known volume should be stored frozen without preservative. Gonadotrophin results should be available within 2-3 weeks; laboratories unable to meet this schedule are advised to send their samples to a Regional Centre for assay. Reagents for the radioimmunoassay of FSH and LH are readily available, and standard techniques have been developed for their use. Laboratories using 'in-house' methods should pay particular attention to the matrix used for preparing standard solutions, the purification of radioligands and the optimisation of the separation system. Low cost matched reagents of proven performance are available in kit form from the Chelsea Hospital for Women; several commercial kits are also available, although few are widely used in the UK. The overall performance of laboratories in the UK External Quality Assessment Scheme (EQAS) for FSH and LH has remained steady for several years. Of the 130 participants, only about 15% in each scheme have 'good' performance (cumulative bias less than 10%, plus cumulative variability of bias less than 10%), whilst a similar proportion have 'unacceptable' performance (cumulative bias greater than 20% and/or cumulative variability of bias greater than 25%). The remaining 70% of laboratories have 'adequate' performance but are at risk of producing results that are clinically misleading. Within any one method group, the performance of FSH and LH assays are closely related. Optimal assay performance depends upon sensible laboratory management to ensure skilled operators, a regular programme of reagent/kit renewal, comprehensive internal and external quality assessment, and attention to detail in all aspects of gonadotrophin assay. The working range of each individual assay should be defined and no absolute result reported from outside this range.(ABSTRACT TRUNCATED AT 400 WORDS)