Laboratory tests for oxidative stress

Abstract

Introduction:Oxidative stress (OS) is considered a significant contributor to male infertility. A number of laboratory techniques have been developed to evaluate oxidative stress in the semen. We review these tests and their current use.Methods:A literature review was performed utilizing the PubMed search engine for articles studying OS etiology and impact on male fertility, and the laboratory tests used in its assessment.Results:The state of OS results from exaggerated production of oxygen-derived free radicals, also known as reactive oxygen species, to an extent overwhelming the body's antioxidant defense mechanisms. Several laboratory tests have been utilized in OS measurement during male fertility evaluation. These tests are classified into direct assays which measure the degree of oxidation within a sperm cell and indirect assays which estimate the detrimental effects of OS. The chemiluminescence assay, flow cytometry, nitroblue tetrazolium assay, and cytochrome c reduction are examples of direct assays while the myeloperoxidase test and measurements of lipid peroxidation, oxidation-reduction potential, and total antioxidant capacity are examples of the indirect assays.Conclusion:OS measurement is an important tool that may help in understanding the pathophysiology of male infertility and provide valuable information that would guide treatment decisions and patient follow-up.

Oxidative stress and sperm function: A systematic review on evaluation and management

“…The measurement of the number of free radicals generated is done as relative light units/ s/10 6 sperm. The range of normal ROS levels in washed sperm suspensions is 0.10-1.03 × 10 6 counted photons per minute per 20 × 10 6 sperm [50].…”

“…The routine analysis of semen parameters (sperm count, morphology and motility) allows clinicians to make an almost perfect diagnosis of OS, where asthenozoospermia is perhaps the best marker for OS [49,50]. The hyperviscosity of seminal plasma marks a rise in seminal plasma MDA and a decrease in seminal plasma antioxidant status [49].…”

“…Luminol is also used for the measurement of the TAC within the seminal plasma, which is quantified against a vitamin E analogue 'Trolox' (a water-soluble tocopherol analogue). The results are articulated as a ROS-TAC score, indicating the combined antioxidant activities evoked by all the constituents, including vitamins, lipids and proteins [50].…”

Changes in sperm function and structure after freezing in domestic cat spermatozoa

“…Reactive oxygen species are highly reactive oxidising agents that, at physiologic levels, are naturally involved in various physiologic pathways essential for normal reproduction. In vivo, they are equilibrated by the presence of various enzymatic and nonenzymatic antioxidants that scavenge and neutralise excessive, and therefore detrimental, amounts of ROS (Agarwal & Ahmad, ). Sperm cryopreservation had been linked to oxidative stress (OS) damage due to an increase in ROS (Ortega‐Ferrusola et al, ).…”

“…The OS results from exaggerated production of oxygen‐derived free radicals (Agarwal & Ahmad, ). To our knowledge, this is the first report of determination after freeze/thawing process in domestic cat spermatozoa.…”