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Topic:Doping

Doping in horses refers to the administration of prohibited substances or methods to enhance performance or alter behavior during competitions. This practice is a concern in equestrian sports due to its potential impact on animal welfare, fair play, and the integrity of the sport. Substances used in doping can range from stimulants and painkillers to sedatives and anti-inflammatory drugs. Detection methods include blood and urine tests, designed to identify the presence of banned substances or their metabolites. This page compiles peer-reviewed research studies and scholarly articles that explore the detection methods, regulatory frameworks, and ethical considerations associated with doping in equine sports.
Liquid chromatography-mass spectrometry analysis of five bisphosphonates in equine urine and plasma.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences    June 20, 2015   Volume 998-999 1-7 doi: 10.1016/j.jchromb.2015.06.020
Wong AS, Ho EN, Wan TS, Lam KK, Stewart BD.Bisphosphonates are used in the management of skeletal disorder in humans and horses, with tiludronic acid being the first licensed veterinary medicine in the treatment of lameness associated with degenerative joint disease. Bisphosphonates are prohibited in horseracing according to Article 6 of the International Agreement on Breeding, Racing and Wagering (published by the International Federation of Horseracing Authorities). In order to control the use of bisphosphonates in equine sports, an effective method to detect the use of bisphosphonates is required. Bisphosphonates are difficult-to-de...
Metabolic study of androsta-1,4,6-triene-3,17-dione in horses using liquid chromatography/high resolution mass spectrometry.
The Journal of steroid biochemistry and molecular biology    May 29, 2015   Volume 152 142-154 doi: 10.1016/j.jsbmb.2015.05.011
Kwok WH, Leung GN, Wan TS, Curl P, Schiff PJ.Androsta-1,4,6-triene-3,17-dione (ATD) is an irreversible steroidal aromatase inhibitor and is marketed as a supplement. It has been reported to effectively reduce estrogen biosynthesis and significantly increase the levels of endogenous steroids such as dihydrotestosterone and testosterone in human. ATD abuses have been reported in human sports. Its metabolism in human has been studied, and the in vitro metabolic study of ATD in horses has been reported, however, little is known about its biotransformation and elimination in horses. This paper describes the in vitro and in vivo metabolism stu...
Cobalt chloride doping in racehorses: Concerns over a potentially lethal practice.
Veterinary journal (London, England : 1997)    April 9, 2015   Volume 205, Issue 3 335-338 doi: 10.1016/j.tvjl.2015.04.005
Mobasheri A, Proudman CJ.No abstract available
Opiorphin analysis in equine plasma and urine using hydrophilic interaction LC-MS.
Bioanalysis    April 1, 2015   Volume 7, Issue 5 593-603 doi: 10.4155/bio.14.289
Wang CC, Hartmann-Fischbach P, Krueger TR, Wells TL, Simonson A, Compton JC.Due to opiorphin's analgesic and antidepressant functions, its illicit use is rumored in some racing jurisdictions. Opiorphin is very difficult to detect due to its hydrophilic nature and rapid degradation in plasma and urine samples. METHODOLOGY & RESULTS: We have developed a sensitive, reliable method for opiorphin detection and confirmation in equine samples, using EDTA to inhibit analyte degradation between the time of collection and analysis. Opiorphin was extracted by weak cation exchange followed by analysis using HILIC-MS/MS. The method was validated and the LOD was determined to b...
Chip-based nanoelectrospray ionization with Fourier transform mass spectrometric detection to screen for local anesthetics intended to mask limb sore in walking horses.
Journal of mass spectrometry : JMS    March 25, 2015   Volume 50, Issue 3 533-537 doi: 10.1002/jms.3558
Szarka S, Prokai L.We report a high-throughput chip-based nanoelectrospray ionization method coupled with Fourier transform mass spectrometry to screen for local anesthetics in samples collected by swabbing. These drugs have been used to mask pain on the limbs of walking horses after forbidden practices of soring or physical abuse. Optimized for lidocaine, the method afforded sub-ppm mass accuracy for nine local anesthetics included in the study. From doped cotton swabs, two third and all of the analytes were detected after adding 10 ng and 100 ng of each drug, respectively. Benzocaine and/or lidocaine were ...
[Alimentary intake of opioid alkaloids by horses. Hazards due to poppy-containing feeds].
Tierarztliche Praxis. Ausgabe G, Grosstiere/Nutztiere    January 27, 2015   Volume 43, Issue 1 35-43 doi: 10.15653/TPG-140638
Hertzsch R, Emmerich IU, Lachenmeier DW, Sproll C, Monakhova YB, Aboling S, Bachmann U, Vervuert I.Opioid alkaloids were identified in the urine of horses during an anti-doping control and in a case of intoxication. In both cases, it was suspected that the horses had ingested poppy-contaminated feed. To verify this suspicion, possible opioid alkaloid sources in Germany were identified through a literature research. Additionally, the contaminated feed was botanically and chemically analysed. The results indicated that both cases were most probably caused by the poppy in the feed. This highlights the previously underestimated risk of an intake of poppy-contaminated feed in horses. Recommendat...
A validated UHPLC-MS/MS method to quantify low levels of anabolic-androgenic steroids naturally present in urine of untreated horses.
Analytical and bioanalytical chemistry    January 17, 2015   Volume 407, Issue 15 4385-4396 doi: 10.1007/s00216-014-8428-x
Decloedt A, Bailly-Chouriberry L, Vanden Bussche J, Garcia P, Popot MA, Bonnaire Y, Vanhaecke L.Doping control is a main priority for regulatory bodies of both the horse racing industry and the equestrian sports. Urine and blood samples are screened for the presence of hundreds of forbidden substances including anabolic-androgenic steroids (AASs). Based on the suspected endogenous origin of some AASs, with β-boldenone as the most illicit candidate, this study aimed to improve the knowledge of the naturally present AAS in horse urine. To this extent, a novel ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated according to...
Characterization of equine urinary metabolites of selective androgen receptor modulators (SARMs) S1, S4 and S22 for doping control purposes.
Drug testing and analysis    January 5, 2015   Volume 7, Issue 8 673-683 doi: 10.1002/dta.1768
Hansson A, Knych H, Stanley S, Thevis M, Bondesson U, Hedeland M.Selective androgen receptor modulators, SARMs, constitute a class of compounds with anabolic properties but with few androgenic side-effects. This makes them possible substances of abuse and the World Anti-Doping Agency (WADA) has banned the entire class of substances. There have been several cases of illicit use of aryl propionamide SARMs in human sports and in 2013, 13 cases were reported. These substances have been found to be extensively metabolized in humans, making detection of metabolites necessary for doping control. SARMs are also of great interest to equine doping control, but the in...
In vitro metabolism studies of desoxy-methyltestosterone (DMT) and its five analogues, and in vivo metabolism of desoxy-vinyltestosterone (DVT) in horses.
Journal of mass spectrometry : JMS    January 1, 2015   Volume 50, Issue 8 994-1005 doi: 10.1002/jms.3613
Kwok WH, Kwok KY, Leung DK, Leung GN, Wong CH, Wong JK, Wan TS.The positive findings of norbolethone in 2002 and tetrahydrogestrinone in 2003 in human athlete samples confirmed that designer steroids were indeed being abused in human sports. In 2005, an addition to the family of designer steroids called 'Madol' [also known as desoxy-methyltestosterone (DMT)] was seized by government officials at the US-Canadian border. Two years later, a positive finding of DMT was reported in a mixed martial arts athlete's sample. It is not uncommon that doping agents used in human sports would likewise be abused in equine sports. Designer steroids would, therefore, pose...
Confirmation and quantification of clenbuterol in horse urine using liquid chromatography tandem mass spectrometry triple quadrupole.
Journal of analytical toxicology    December 11, 2014   Volume 39, Issue 2 130-132 doi: 10.1093/jat/bku140
Bishop J, Heffron B, Taddei L, Benoit M, Hurt L, Costello S, Gross M, Negrusz A.Clenbuterol (CLE) is used in horses as a bronchodilator and for its anabolic steroid-like effects. CLE is a Class 3 drug according to current Association of Racing Commissioners International (ARCI) Uniform Classification Guidelines. The Racing Medication and Testing Consortium recommended a urine CLE threshold of 140 pg/mL after careful scientific review of the results of studies describing the disposition of CLE in the horse and this threshold was adopted by the ARCI. Enzyme-linked immunosorbent assay was previously used to screen samples for CLE in Illinois, but could not detect such low co...
Selective and simultaneous determination of NSAIDs in equine plasma by HPLC with molecularly imprinted solid-phase extraction.
Bioanalysis    October 22, 2014   Volume 6, Issue 16 2147-2158 doi: 10.4155/bio.14.79
Meucci V, Minunni M, Vanni M, Sgorbini M, Corazza M, Intorre L.Detection of nonsteroidal anti-inflammatory drugs (NSAIDs) in equine plasma is a significant analytical problem in veterinary anti-doping controls. Results: A new HPLC method coupled to selective extraction with molecularly imprinted polymers was developed for the simultaneous determination in equine plasma of the NSAIDs phenylbutazone, flunixin, oxyphenbutazone, ketoprofen and naproxen. The analytical performances of the method have been evaluated both in standard solutions and equine plasma samples. Recovery: Molecularly imprinted polymers solid-phase extraction for all NSAIDs was >94% wi...
Development and validation of a hydrophilic interaction liquid chromatography with tandem mass spectrometry method for the simultaneous detection and quantification of etilefrine and oxilofrine in equine blood plasma and urine.
Journal of separation science    September 30, 2014   Volume 37, Issue 21 3015-3023 doi: 10.1002/jssc.201400662
Kong N, Yi R, Zhao S, Sandhu J, Lam G, Loganathan D, Morrissey B.A sensitive hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry method was developed and validated for the simultaneous detection and quantification of etilefrine and oxilofrine in equine blood plasma and urine. The method is highly sensitive and specific with good precision and accuracy. In plasma the limit of detection and limit of quantification are 0.03 and 0.1 ng/mL, respectively, for both analytes. In urine the limit of detection and limit of quantification are 0.3 and 1 ng/mL, respectively, for both analytes. The suitability of the method for doping con...
Controlling the misuse of cobalt in horses.
Drug testing and analysis    September 25, 2014   Volume 7, Issue 1 21-30 doi: 10.1002/dta.1719
Ho EN, Chan GH, Wan TS, Curl P, Riggs CM, Hurley MJ, Sykes D.Cobalt is a well-established inducer of hypoxia-like responses, which can cause gene modulation at the hypoxia inducible factor pathway to induce erythropoietin transcription. Cobalt salts are orally active, inexpensive, and easily accessible. It is an attractive blood doping agent for enhancing aerobic performance. Indeed, recent intelligence and investigations have confirmed cobalt was being abused in equine sports. In this paper, population surveys of total cobalt in raceday samples were conducted using inductively coupled plasma mass spectrometry (ICP-MS). Urinary threshold of 75 ng/mL a...
Detection and pharmacokinetics of salbutamol in thoroughbred racehorses following inhaled administration.
Journal of veterinary pharmacology and therapeutics    September 17, 2014   Volume 38, Issue 1 41-47 doi: 10.1111/jvp.12150
Wieder ME, Paine SW, Hincks PR, Pearce CM, Scarth J, Hillyer L.Salbutamol sulphate (Ventolin Evohaler) was administrated via the inhalation route to six horses at a dose of 0.5 mg every 4 h during the day for 2 days (total dose 4 mg). Urine and blood samples were taken up to 92 h postadministration. Hydrolyzed plasma and urine were extracted using solid phase extraction (SPE). A sensitive tandem mass spectrometric method was developed in this study, achieving a lower limit of quantification (LLOQ) for salbutamol of 10 pg/mL in plasma and urine. The parent drug was identified using UPLC-MS/MS. Most of the determined salbutamol plasma concentrations, post l...
Equine total carbon dioxide testing in Illinois in 2012.
Journal of analytical toxicology    September 14, 2014   Volume 38, Issue 8 536-540 doi: 10.1093/jat/bku095
Heffron B, Benoit M, Bishop J, Costello S, Hurt L, Simpson L, Taddei L, Kline K, Negrusz A.During prolonged strenuous exercise, racehorses can experience acidemia. To counteract this phenomenon, trainers can administer blood alkalizing agents that raise the plasma pH and total carbon dioxide (TCO2) concentration. In Illinois, the administrative threshold for TCO2 in plasma is 37.0 mmol/L. Because accuracy in the reported measurement of TCO2 must be ensured, uncertainty measurements are often issued alongside the reported concentrations. We report a validated method for measuring TCO2 levels in equine plasma using the Beckman UniCel DxC 600. A six-point calibration curve ranging from...
Control of the misuse of testosterone in castrated horses based on an international threshold in plasma.
Drug testing and analysis    May 28, 2014   Volume 7, Issue 5 414-419 doi: 10.1002/dta.1681
Ho EN, Kwok WH, Leung DK, Riggs CM, Sidlow G, Stewart BD, Wong AS, Wan TS.Testosterone is an endogenous steroid produced primarily in the testes. Trace levels of testosterone are found in urine samples from geldings, as testosterone is also secreted by the adrenal. An international threshold of free and conjugated testosterone in urine (20 ng/mL) was adopted by the International Federation of Horseracing Authorities (IFHA) in 1996 for controlling testosterone misuse in geldings. In view of the recent popularity of using blood in doping control testing, it is necessary to establish a threshold for testosterone in gelding plasma. A liquid chromatography-mass spectro...
An easy stereoselective synthesis of 5(10)-estrene-3β,17α-diol, a biological marker of pregnancy in the mare.
Steroids    May 1, 2014   Volume 86 1-4 doi: 10.1016/j.steroids.2014.04.009
Balssa F, Fischer M, Bonnaire Y.5(10)-Estrene-3β,17α-diol is an essential reference material for doping analysis in horse-racing laboratories. It is used to detect misuse, for doping purpose, of the pregnancy status in the mare. Its stereoselective synthesis from 17β-estradiol-3-methyl ether (prepared from estrone or 17β-estradiol) was performed in four steps: (1) Mitsunobu inversion of the 17β-alcohol; (2) Birch reduction of the aromatic ring; (3) stereoselective reduction of the 3-ketone via Noyori asymmetric transfer hydrogenation; (4) chemoenzymatic purification.
Inhibitory effect of triamcinolone acetonide on synthesis of inflammatory mediators in the equine.
European journal of pharmacology    April 18, 2014   Volume 736 1-9 doi: 10.1016/j.ejphar.2014.04.013
Mangal D, Uboh CE, Soma LR, Liu Y.Glucocorticoids (corticosteroids) are widely used anti-inflammatory agents in veterinary medical practice. These drugs are considered doping agents because they mask pain and thus, increase injury potential in equine athletes. They exhibit anti-inflammatory property by binding to glucocorticoids receptor (GR) to control the transcription of pro- and anti-inflammatory cytokines and enzymes involved in the synthesis of bioactive eicosanoids. To evaluate the role of triamcinolone acetonide (TA) on concentrations of bioactive eicosanoids in equine plasma, TA (0.04 mg/kg) was intravenously administ...
A rapid screen for four corticosteroids in equine synovial fluid.
Journal of analytical toxicology    April 8, 2014   Volume 38, Issue 5 272-279 doi: 10.1093/jat/bku030
Agrawal K, Ebel JG, Bischoff K.Most antidoping method development in the equine industry has been for plasma and urine, though there has been recent interest in the analysis of synovial fluid for evidence of doping by intra-articular corticosteroid injection. Published methods for corticosteroid analysis in synovial fluid are primarily singleplex methods, do not screen for all corticosteroids of interest and are not adequately sensitive. The purpose of this study is to develop a rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) screening method for the detection of four of the most common intra-a...
Evaluation of horse urine sample preparation methods for metabolomics using LC coupled to HRMS.
Bioanalysis    April 8, 2014   Volume 6, Issue 6 785-803 doi: 10.4155/bio.13.324
Stojiljkovic N, Paris A, Garcia P, Popot MA, Bonnaire Y, Tabet JC, Junot C.Horse urine is the medium of choice for the implementation of metabolomic approaches aimed at improving horse doping control. However, drug analysis in this biofluid is a challenging task due to the presence of large amounts of interfering compounds. METHODOLOGY & RESULTS: A comparative study of sample preparation has been conducted to evaluate five sample-preparation methods, namely acetonitrile precipitation, proteinase K hydrolysis, membrane filtration and sample dilution with water by factors of five and 20, for metabolome analysis using liquid chromatography coupled to high resolution...
Doping control analysis of filgrastim in equine plasma and its application to a co-administration study of filgrastim and recombinant human erythropoietin in the horse.
Journal of chromatography. A    February 28, 2014   Volume 1338 92-101 doi: 10.1016/j.chroma.2014.02.064
Ho EN, Kwok WH, Lau MY, Wong AS, Lam KK, Stewart BD, Wan TS.Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor regulating granulopoiesis. The recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used for the treatment of granulopenia in humans. Filgrastim is a rhG-CSF analogue and is marketed under various brand names, including Neupogen(®) (Amgen), Imumax(®) (Abbott Laboratories), Neukine(®) (Intas Biopharmaceuticals) and others. It is banned in both human and equine sports owing to its potential for misuse. In order to control the abuse of filgrastim in equine sports, a method to identify unequivo...
A high-throughput LC-MS/MS screen for GHRP in equine and human urine, featuring peptide derivatization for improved chromatography.
Drug testing and analysis    February 24, 2014   Volume 6, Issue 10 985-995 doi: 10.1002/dta.1624
Timms M, Hall N, Levina V, Vine J, Steel R.The growth hormone releasing peptides (GHRPs) hexarelin, ipamorelin, alexamorelin, GHRP-1, GHRP-2, GHRP-4, GHRP-5, and GHRP-6 are all synthetic met-enkephalin analogues that include unnatural D-amino acids. They were designed specifically for their ability to stimulate growth hormone release and may serve as performance enhancing drugs. To regulate the use of these peptides within the horse racing industry and by human athletes, a method is presented for the extraction, derivatization, and detection of GHRPs from equine and human urine. This method takes advantage of a highly specific solid-ph...
Detection of efaproxiral (RSR13) and its metabolites in equine by liquid chromatography tandem mass spectrometry.
Journal of mass spectrometry : JMS    January 22, 2014   Volume 49, Issue 1 57-67 doi: 10.1002/jms.3304
Yi R, Sandhu J, Zhao S, Lam G, Loganathan D, Morrissey B.Efaproxiral (RSR 13) is an experimental synthetic allosteric modifier of haemoglobin (Hb) that acts by increasing the release of oxygen from Hb to the surrounding tissues. It has been shown to increase maximum oxygen uptake (VO(2max)) in a canine skeletal muscle model. The ability to increase maximal muscle oxygen uptake makes efaproxiral a potential performance-enhancing agent and is therefore prohibited by the World Anti-Doping Agency. In this study, a method for the detection and elimination of efaproxiral in equine plasma and urine after a 2.5 g intravenous administration of efaproxiral ...
Doping control analyses in horseracing: a clinician’s guide.
Veterinary journal (London, England : 1997)    January 17, 2014   Volume 200, Issue 1 8-16 doi: 10.1016/j.tvjl.2014.01.006
Wong JK, Wan TS.Doping(1) in sports is highly detrimental, not only to the athletes involved but to the sport itself as well as to the confidence of the spectators and other participants. To protect the integrity of any sport, there must be in place an effective doping control program. In human sports, a 'top-down' and generally unified approach is taken where the rules and regulations against doping for the majority of elite sport events held in any country are governed by the World Anti-Doping Agency (WADA). However, in horseracing, there is no single organisation regulating this form of equestrian sport; i...
Sensitive hydrophilic interaction liquid chromatography/tandem mass spectrometry method for rapid detection, quantification and confirmation of cathinone-derived designer drugs for doping control in equine plasma.
Rapid communications in mass spectrometry : RCM    December 18, 2013   Volume 28, Issue 2 217-229 doi: 10.1002/rcm.6778
Li X, Uboh CE, Soma LR, Liu Y, Guan F, Aurand CR, Bell DS, You Y, Chen J, Maylin GA.Cathinone derivatives are new amphetamine-like stimulants that can evade detection when presently available methods are used for doping control. To prevent misuse of these banned substances in racehorses, development of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method became the impetus for undertaking this study. Methods: Analytes were recovered via liquid-liquid extraction using methyl tert-butyl ether. Analyte separation was achieved on a hydrophilic interaction column using liquid chromatography and mass analysis was performed on a QTRAP mass spectrometer in positive elec...
Scopolamine in racing horses: trace identifications associated with dietary or environmental exposure.
Veterinary journal (London, England : 1997)    December 14, 2013   Volume 199, Issue 3 324-331 doi: 10.1016/j.tvjl.2013.12.013
Brewer K, Dirikolu L, Hughes CG, Tobin T.Scopolamine (L-hyoscine) identifications, often in small-number clusters, have been reported worldwide in performance horses over the last 30 years. Scopolamine is an Association of Racing Commissioners International (ARCI) class 3, penalty class B, substance with potential to affect performance. As such, scopolamine identification(s) in race or performance horses can result in significant penalties for the connections of the horse(s). Reviewed here is the worldwide distribution of scopolamine containing plants (primarily Datura spp.), with estimates of their potential toxicity to horses throu...
Detection and quantification of dermorphin and selected analogs in equine urine.
Bioanalysis    December 11, 2013   Volume 5, Issue 24 2995-3007 doi: 10.4155/bio.13.281
Richards SL, Cawley AT, Raftery MJ.Dermorphin, a hepta-peptide with potent analgesic properties, is classified as a doping agent in equine racing. Since its discovery, a number of biologically active structural analogs have been synthesized and made commercially available so there is a need for reliable methods of detection. Results: A sensitive detection method was developed for dermorphin and six analogs in equine urine. Peptide enrichment was achieved using weak cation exchange with subsequent separation and detection by nano-UHPLC-MS/MS. Method validation parameters included: specificity, linearity (5-10000 pg/ml), recovery...
A generic screening methodology for horse doping control by LC-TOF-MS, GC-HRMS and GC-MS.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences    October 16, 2013   Volume 941 69-80 doi: 10.1016/j.jchromb.2013.10.008
In the present study a general screening protocol was developed to detect prohibited substances and metabolites for doping control purposes in equine sports. It was based on the establishment of a unified sample preparation and on the combined implementation of liquid and gas chromatographic MS analysis. The sample pretreatment began with two parallel procedures: enzymatic hydrolysis of sulfate and glucuronide conjugates, and methanolysis of the 17β-sulfate steroid conjugates. The extracts were treated for LC-TOF-MS, GC-HRMS and GC-MS assays. The majority of the prohibited substances were ide...
Quantitation of fluphenazine in equine serum following fluphenazine decanoate administration.
Journal of analytical toxicology    August 28, 2013   Volume 37, Issue 8 594-599 doi: 10.1093/jat/bkt073
Costello S, Heffron B, Taddei L, Benoit M, Hurt L, Simpson L, Bishop J, Folker-Calderon D, Negrusz A.Fluphenazine, a potent antipsychotic used to treat schizophrenia in humans, is used in racehorses as a performance-enhancing drug, and for that reason it has been banned by the Association of Racing Commissioners International. A liquid chromatography-tandem mass spectrometry method for detecting and quantitating fluphenazine in equine serum was developed and validated. The method was then employed to quantitate fluphenazine in serum samples collected from three study horses after intramuscular injection of fluphenazine decanoate. Stability testing showed that fluphenazine is stable in unextra...
Monitoring the endogenous steroid profile disruption in urine and blood upon nandrolone administration: An efficient and innovative strategy to screen for nandrolone abuse in entire male horses.
Drug testing and analysis    August 15, 2013   Volume 6, Issue 4 376-388 doi: 10.1002/dta.1520
Kaabia Z, Dervilly-Pinel G, Popot MA, Bailly-Chouriberry L, Plou P, Bonnaire Y, Le Bizec B.Nandrolone (17β-hydroxy-4-estren-3-one) is amongst the most misused endogenous steroid hormones in entire male horses. The detection of such a substance is challenging with regard to its endogenous presence. The current international threshold level for nandrolone misuse is based on the urinary concentration ratio of 5α-estrane-3β,17α-diol (EAD) to 5(10)-estrene-3β,17α-diol (EED). This ratio, however, can be influenced by a number of factors due to existing intra- and inter-variability standing, respectively, for the variation occurring in endogenous steroids concentration levels in a si...
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