Before hormonal assays were available, endocrine diseases were assessed by measuring the clinical damage that resulted. For instance, prior to the establishment of clinical assays for growth hormone, patients with acromegaly at Hammersmith Hospital, London, were asked to immerse their hand in a cylinder of water to measure the volume of displacement. A tattoo on the wrist marked the extent to which the patient’s hand should be immersed.
We now have access to a range of hormonal assays that directly measure the activity of endocrine diseases. But it is important to consider whether further assays are required. You may recall the classic conundrum: if a tree falls in the forest and no one is there, does it still make a sound? Regardless of the answer, I think the solution is to develop a better way of hearing those pesky trees!
I have recently gone through the process of assay development, by setting up a novel biochemical semen reactive oxygen species (ROS) assay, which may improve the clinical information we give to couples with infertility, over and above standard semen analysis.
The process of assay development involves several stages, requiring careful thought.
1. CONSIDER FEASIBILITY
Your proposed assay should improve the clinical assessment of patients, over and above currently available tests. Five percent of couples have male factor infertility, but standard semen analysis gives limited information about sperm quality, and is highly labour-intensive. Semen ROS can be measured using a relatively straightforward enzyme assay. Furthermore, published studies suggest that semen ROS is associated with sperm DNA damage and poor fertility outcomes in couples with male infertility.
2. WILL CLINICIANS OR RESEARCHERS USE YOUR ASSAY?
Setting up an assay service is a major undertaking, so you need to check that clinicians and/or researchers will request the test. Speaking to colleagues both within and outside your hospital will answer this question. I was reassured to find that gynaecologists and urologists at my hospital were particularly interested in measuring ROS levels in semen.
3. WHAT RESOURCES DO YOU NEED TO DELIVER THE ASSAY?
'Setting up an assay service is a major undertaking, so you need to check that clinicians and/or researchers will request the test'
A reference laboratory needs physical space (which may simply be a bench area), equipment to perform the assay, staff to undertake and report the measurements, and necessary consumables. At this point, it is essential to sit down with a pathology scientist or lab manager to work out a solution. They will ultimately want to determine whether the anticipated number of tests performed would cover the costs of the service. This might feel a bit like ‘Dragon’s Den’, so come prepared!
4. ASSAY VALIDATION
This process needs to be led by your colleagues in pathology. They will produce a standard operating procedure (SOP) for performing the test and operating all relevant equipment. Assay validation involves establishing several parameters relating to the test. These include measuring assay sensitivity and coefficient of variation.
5. ASSAY ACCREDITATION
Clinical laboratory results in an NHS hospital need to meet minimum quality standards. For instance, the laboratory needs to undertake regular audits to ensure that staff members are performing the assay within acceptable parameters, and that lab equipment is functioning. Your pathology colleagues will provide invaluable expertise regarding the process of certification through bodies such as the UK Accreditation Service (UKAS).
6. PERIODICAL REFINEMENT OF THE TEST
Talking to your referring clinicians will enable you to decide if factors such as reporting style, speed of reporting or elements of the assay itself require improvement. Future technological advances may enable you to make the assay method more accurate or efficient.
Historically, assay development has been the life-blood of endocrinology, by influencing the way we treat patients and understand endocrine disease itself. Setting up a reference lab is hard work but lots of fun, and is highly influential both in academic and clinical endocrinology. Join in!
Channa Jayasena, Clinical Senior Lecturer in Endocrinology, Imperial College London
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