Simultaneous determination of cortisol and cortisone in urine by reversed-phase high-performance liquid chromatography. Clinical and doping control applications

Simultaneous determination of cortisol, cortisone, 6β-hydroxycortisol and 6β-hydroxycortisone by HPLC

A specific and sensitive method based on high-performance liquid chromatography with ultraviolet absorbance detection (HPLC-UV) was developed for the simultaneous determination of urinary cortisol (F), cortisone (E), 6β-hydroxycortisol (6β-OHF) and 6β-hydroxycortisone (6β-OHE) using dexamethasone as the internal standard. The method involved solid-phase extraction of the five compounds from urine using Oasis HLB Waters cartridges with an elution solvent of ethyl acetate-diethyl ether (5 mL; 4:1, v/v), followed by 1 mol/L of NaOH (1 mL) and 1.0% acetic acid (1 mL). Separation of the five analytes was achieved within 31 min by using a reversed-phase C18 analytical column (200 × 4.6 mm, 5 µm, Agilent). A UV detector operated at 245 nm was used. According to the method validation, inter-run and intra-run precision was below 9.45% and accuracy ranged from 98.16 to 115.50%. The lower limits of quantitation were 5 ng/mL for four analytes. This is the first HPLC method that can simultaneously determine F, E, 6β-OHF and 6β-OHE in human urine. The assay was applied to research the ratio of (6β-OHF + 6β-OHE)/(F + E) as a non-invasive biomarker for the metabolism of tacrolimus.

Bone complications in patients with Cushing's syndrome: looking for clinical, biochemical, and genetic determinants

SUMMARY

This is the first study examining the impact of both clinical, biochemical, and genetic determinants in the occurrence of bone complications in patients with overt Cushing's syndrome (CS). It demonstrates that the degree and duration of hypercortisolism seem to play a major role in bone loss and fractures development in these patients.

INTRODUCTION

Bone loss and fractures are a common complication of CS. We investigate the role of gender, disease etiology, duration, and degree of hypercortisolism as well as the impact of glucocorticoid receptor (GR) polymorphisms on the development of bone complications in CS.

METHODS

Fifty-two patients with active CS (38 Cushing's disease and 14 with cortisol-secreting adrenal adenoma) were genotyped for GR polymorphisms (BclI, N363S, ER22/23EK, and A3669G). In all patients, clinical, hormonal, and biochemical markers of bone turnover, densitometric parameters [lumbar spine and left femur bone mineral density (BMD), T-score, Z-score] as well as the prevalence of bone demineralization and both vertebral and peripheral fractures were assessed.

RESULTS

No differences were found in bone complications according to gender, disease etiology, and genetic variants distribution. Fractured patients compared to non-fractured ones showed increased levels of urinary free cortisol (UFC) and a more compromised densitometric profile. UFC levels correlated with the occurrence of vertebral fractures (r = 0.43, p = 0.009) while midnight serum cortisol correlated with L1-L4 BMD values (r = -0.35, p = 0.04). Disease duration correlated with the presence of peripheral fractures (r = 0.36, p = 0.04).

CONCLUSIONS

While GR gene variants as well as gender and disease etiology seem not to play a role, the degree and duration of hypercortisolism seem to be the major determinants of bone loss and fractures in this group of patients. More investigations are needed to understand the real impact of these determinants on the development of bone complications in patients with hypercortisolism.

Chemometric evaluation of urinary steroid hormone levels as potential biomarkers of neuroendocrine tumors

Neuroendocrine tumors (NETs) are uncommon tumors which can secrete specific hormone products such as peptides, biogenic amines and hormones. So far, the diagnosis of NETs has been difficult because most NET markers are not specific for a given tumor and none of the NET markers can be used to fulfil the criteria of high specificity and high sensitivity for the screening procedure. However, by combining the measurements of different NET markers, they become highly sensitive and specific diagnostic tests. The aim of the work was to identify whether urinary steroid hormones can be identified as potential new biomarkers of NETs, which could be used as prognostic and clinical course monitoring factors. Thus, a rapid and sensitive reversed-phase high-performance liquid chromatographic method (RP-HPLC) with UV detection has been developed for the determination of cortisol, cortisone, corticosterone, testosterone, epitestosterone and progesterone in human urine. The method has been validated for accuracy, precision, selectivity, linearity, recovery and stability. The limits of detection and quantification were 0.5 and 1 ng mL⁻¹ for each steroid hormone, respectively. Linearity was confirmed within a range of 1–300 ng mL⁻¹ with a correlation coefficient greater than 0.9995 for all analytes. The described method was successfully applied for the quantification of six endogenous steroid levels in human urine. Studies were performed on 20 healthy volunteers and 19 patients with NETs. Next, for better understanding of tumor biology in NETs and for checking whether steroid hormones can be used as potential biomarkers of NETs, a chemometric analysis of urinary steroid hormone levels in both data sets was performed.

Validation and application of a highly specific and sensitive ELISA for the estimation of cortisone in saliva, urine and in vitro cell-culture media by using a novel antibody

It is generally acknowledged that local tissue concentrations of cortisol and cortisone are modulated by site-specific actions of 11β-hydroxysteroid dehydrogenase (11β-HSD) isoenzymes 1 and 2. Cortisone, the inactive metabolite of cortisol is produced by 11βHSD type 2. To assess 11β-HSD types 1 and 2 activities, the cortisol/cortisone ratio has to be accurately determined. Immunoassays to measure cortisone levels are not widely available and tend to lack specificity. The aim of this project was to develop a highly specific and sensitive ELISA method for the estimation of free cortisone levels in urine, saliva and in vitro media samples without chromatographic separation. Antibodies against cortisone were raised in rabbits using cortisone-3-CMO-KLH as immunogen. HRP-goat anti-rabbit IgG conjugate was used as enzyme tracer. Cross-reactivities of the untreated cortisone antiserum with major interfering steroids were minimal except for cortisol (3.15%). However, following an immune-affinity purification of the antibodies using CNBr-activated sepharose-cortisol-3-CMO-BSA, cross-reactivity of the purified cortisone antibody with cortisol was reduced to 0.27%. The minimum detection limit of cortisone ELISA was 28 pg/mL (77.7 pM). The validity of the cortisone ELISA was confirmed by the excellent correlation obtained before and after an HPLC fractionation step (Y=1.09X-0.21, R2=0.98). Intra-assay and inter-assay imprecision were 5.5-11.7% and 8.7-12.8% CV, respectively. Using this assay, salivary cortisone levels showed a circadian rhythm in men and women (11.2±7.3 nM at 08.00 h and 5.1±3.6 nM at 18.00 h), and the levels were reduced following liquorice ingestion. In media of adrenocortical H295 cell line incubations, basal cortisone levels were 4.24±0.22 nM that increased to 8.6±1.2 nM post forskolin treatment. Urinary free cortisone excretion levels in healthy subjects were 56.66±36.9 nmol/day. In human volunteers following ingestion of green coffee bean extract for 2 weeks, urinary free cortisol excretion reduced significantly from 66.67±22.3 to 42.66±17.5 nmol/day (p=0.02) and the cortisol/cortisone ratio from 2.04±1.33 to 1.49±1.13, p=0.05. In conclusion, a simple and highly specific and sensitive ELISA has been developed and applied to estimate cortisone levels in biological fluids and culture media.

Association of glucocorticoid receptor polymorphism A3669G with decreased risk of developing diabetes in patients with Cushing's syndrome

OBJECTIVE

Glucocorticoid receptor (GR) polymorphisms alter glucocorticoid (GC) sensitivity and have been associated with altered metabolic profiles. We evaluate the prevalence of the four GR (NR3C1) polymorphisms BclI, N363S, ER22/23EK, and A3669G in patients with Cushing's syndrome (CS) compared with healthy controls (HC) and we investigate their role in the development of metabolic abnormalities in patients with CS according to their hormonal profile.

PATIENTS AND METHODS

Sixty-one patients with CS and 71 sex- and age-matched HC were genotyped.

RESULTS

BclI variant was markedly higher in patients with CS compared with HC (62 vs 41%, P<0.05) while no significant differences were found among other polymorphisms. A very low frequency of N363S and the ER22/23EK was observed. In CS patients, despite the significantly increased levels of morning serum cortisol in BclI carriers compared with wild type no clinical or metabolic differences were found. In contrast, A3669G GR carriers showed a significantly reduced prevalence of type 2 diabetes mellitus compared with wild type (19 vs 68%, P=0.001) despite the higher levels of both serum morning (21.7±6 vs 27.3±8.6 μg/dl, P=0.009) and midnight cortisol (18.8±5.8 vs 24.0±8.0 μg/dl, P=0.01). The negative association between diabetes and A3669G GR polymorphism remained significant when data were adjusted for potential confounding factors.

CONCLUSIONS

The A3669G polymorphism of the GR gene plays a protective role in patients with CS, attenuating the effects of GC excess on glucose metabolism as shown by their reduced risk of diabetes.

Doping and musculoskeletal system: short-term and long-lasting effects of doping agents

Doping is a problem that has plagued the world of competition and sports for ages. Even before the dawn of Olympic history in ancient Greece, competitors have looked for artificial means to improve athletic performance. Since ancient times, athletes have attempted to gain an unfair competitive advantage through the use of doping substances. A Prohibited List of doping substances and methods banned in sports is published yearly by the World Anti-Doping Agency. Among the substances included are steroidal and peptide hormones and their modulators, stimulants, glucocorticosteroids, β₂-agonists, diuretics and masking agents, narcotics, and cannabinoids. Blood doping, tampering, infusions, and gene doping are examples of prohibited methods indicated on the List. Apart from the unethical aspect of doping, as it abrogates fair-play's principle, it is extremely important to consider the hazards it presents to the health and well-being of athletes. The referred negative effects for the athlete's health have to do, on the one hand, by the high doses of the performance-enhancing agents and on the other hand, by the relentless, superhuman strict training that the elite or amateur athletes put their muscles, bones, and joints. The purpose of this article is to highlight the early and the long-lasting consequences of the doping abuse on bone and muscle metabolism.

Multi-detection of corticosteroids in sports doping and veterinary control using high-resolution liquid chromatography/time-of-flight mass spectrometry

A liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) method was developed using the latest high-resolution LC column technology, the ultra performance liquid chromatography (UPLC), and electrospray ionization (ESI) in the positive ion mode. Gradient UPLC separation conditions were optimized for a group of 22 analytes comprising 17 glucocorticosteroids, specific designer steroids such as tetrahydrogestrinone (THG) and specific beta2-agonists such as formoterol. The UPLC/TOFMS separation obtained required 5.5 min only for all the substances tested. Even the critical pair of dexamethasone and betamethasone isomers was almost completely resolved. Thanks to the over 10,000 full-width at half maximum (FWHM) mass resolution and high mass accuracy features of TOFMS 50 mDa window accurate mass chromatograms could be reconstructed for the individual analytes. Sensitive screening in human and calf urine samples fortified at the glucocorticosteroids minimum required performance limit (MRPL) of 30 microg L(-1) (human urine, sports doping) and 2 microg L(-1) (calf urine, veterinary control) could be obtained. The potential of UPLC/TOFMS for confirmatory analysis was shown by determining the accurate mass of all compounds and fragment ions upon in-source collision-induced dissociation (CID) at different energies. The exact mass measurement errors for all glucocorticosteroids were found to be within 6 ppm. Considering veterinary control, limits of detection (LOD) and limits of quantification (LOQ) were determined for most of the analytes in calf urine and found to range from 0.1 to 3.3 and from 0.4 to 4.4 microg L(-1), respectively. The method can be easily extended with other banned substances of interest, as demonstrated by the addition of 21 beta2-agonists to the original analyte mixture in urine, without causing any interferences.

An HPLC method for the determination of the free cortisol/cortisone ratio in human urine

The measurement of the urinary free cortisol-cortisone ratio has been reported to be a sensitive indicator of renal 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD 2) activity. This converts biologically active cortisol to inactive cortisone. A decrease in its activity (e.g. through disease or inhibition caused by a therapeutic agent or a foodstuff) may increase cortisol levels and susceptibility towards hypertension. The method presented here uses a simple isocratic tandem column HPLC system. The method has been validated and found to be robust and reproducible. The lower limit of quantification (LLOQ) was found to be 10 ng/mL for both cortisol and cortisone. Samples of urine (n = 99) from patients, most of whom were on complex combinations of drugs, were analyzed and 92% of samples were found to give successful results with this method (cortisol and cortisone above LLOQ). The ratio ranged from 0.07 to 5.61. No interferences were noted from the drugs that the patients were taking. It was also found that a morning spot urine sample gave comparable results to 24 h collection samples, thus making sample collection much easier.

Variability of cortisol assays can confound the diagnosis of adrenal insufficiency in the critically ill population

OBJECTIVE

To compare the total plasma cortisol values obtained from three widely used immunoassays and a high pressure liquid chromatography (HPLC) technique on samples obtained from patients with sepsis.

DESIGN AND SETTING

Observational interventional in the general intensive care unit of a metropolitan hospital

PATIENTS AND PARTICIPANTS

Patients admitted to the intensive care unit with a diagnosis of sepsis and fulfilling criteria of systemic inflammatory response syndrome.

INTERVENTIONS

Standard short synacthen test performed with 250microg cosyntropin.

MEASUREMENTS AND RESULTS

Two of the three immunoassays returned results significantly higher than those obtained by HPLC: Immulite by 95% (95%CI 31-188%) and TDx by 79% (21-165%). The limits of agreement for all three immunoassays with HPLC ranged from -62% to 770%. In addition, by classifying the patients into responders and non-responders to ACTH by standard criteria there was concordance in all assays in only 44% of patients.

CONCLUSIONS

Immunoassay estimation of total plasma cortisol in septic patients shows wide assay related variation that may have significant impact in the diagnosis of relative adrenal insufficiency.

Glucocorticosteroids in football: use and misuse

BACKGROUND AND OBJECTIVES

Glucocorticosteroids are widely used in medicine and have shown unchallenged therapeutic potential in several chronic inflammatory and other diseases. They are also widely used in sports medicine for the treatment of conditions such as asthma and acute injuries. In fact, as banned substances, most requests for therapeutic use exemption concern glucocorticosteroids. Nevertheless, their beneficial effect in certain conditions in sports, where inflammation is only a secondary reaction, remains to be validated. This paper aimed to provide a comprehensive review of the literature covering the therapeutic use of glucocorticosteroids since 1977 in conditions ranging from chronic rheumatic illness to peritendinous or intra-articular injection in acute injuries.

METHODS

Search of the medical literature published between 1977 and 2006 using PubMed. Articles relevant to the question "When and if at all is the use of glucocorticosteroids justified in football?" were selected and analysed.

RESULTS AND CONCLUSIONS

The findings clearly point out that, despite the common use of glucocorticosteroids in acute injuries in sports, there is actually limited evidence of the true benefits of such a practice. Physicians must take the possible adverse effects into consideration. In an athlete with clinically verified asthma, inhalational glucocorticosteroids remain first line therapy. Finally, for the purposes of education and prevention of misuse, it should be stressed that a measurable performance enhancing effect of glucocorticoids could not be proved on the basis of the results of the scientific studies to date.

High cardiovascular risk in patients with Cushing's syndrome according to 1999 WHO/ISH guidelines

OBJECTIVE

In patients with Cushing's syndrome (CS) cardiovascular complications determine a mortality rate four times higher than in an age- and gender-matched population. Therefore, we calculated the global cardiovascular risk in patients with CS.

DESIGN AND PATIENTS

We applied the World Health Organization--International Society of Hypertension (WHO/ISH) 1999 guidelines for the estimation of cardiovascular risk in 38 females and 11 males with CS; 27 pituitary adenomas, 15 adrenal adenomas, four adrenal carcinomas and three ectopic ACTH-secreting tumours. The risk of major cardiovascular events was estimated considering the combined effect of several risk factors (hypertension, diabetes, etc.), organ damage (left ventricular hypertrophy (LVH), proteinuria, etc.) and associated pathologies. Four categories of absolute cardiovascular disease risk were defined (low, medium, high, very high).

RESULTS

Eighty per cent of patients presented a 'high' or 'very high' cardiovascular risk; 85.1% of the patients were hypertensive with a mild-moderate hypertension (68%). Forty-seven per cent of patients were diabetics and 41.3% were obese. Hyperlipidaemia was less frequent (37.5%). Fasting glycaemia was the only cardiovascular risk factor that correlated with a degree of hypercortisolism. Duration of disease correlated with the presence of obesity (P < 0.0008) and hypertension (P < 0.03) but not with the presence of diabetes or dyslipidaemia and seemed to be the only significant predictor of cardiovascular risk (P = 0.03).

CONCLUSIONS

Patients with active CS present a remarkably increased cardiovascular risk. Considering that the biochemical cure of hypercortisolism is often difficult to obtain, especially in Cushing's disease, and that cardiovascular risk could persist even after the 'cure', control of risk factors should be one of the primary goals of the therapy.

Renal clearance and daily excretion of cortisol and adrenal androgens in patients with rheumatoid arthritis and systemic lupus erythematosus

BACKGROUND

In rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), patients demonstrate low levels of adrenal hormones.

OBJECTIVE

To investigate whether increased renal clearance and daily excretion contribute to this phenomenon.

METHODS

Thirty patients with RA, 32 with SLE, and 54 healthy subjects (HS) participated. Serum and urinary levels of cortisol, cortisone, 17-hydroxyprogesterone (17OHP), androstenedione, dehydroepiandrosterone (DHEA), and DHEA sulphate (DHEAS) were measured.

RESULTS

Clearance of DHEAS and DHEA was lower in patients than in HS, and clearance of androstenedione was somewhat higher in patients than in HS, but daily excretion of this latter hormone was low. Clearance of cortisol, cortisone, and 17OHP was similar between the groups. The total molar amount per hour of excreted DHEA, DHEAS, and androstenedione was lower in patients than HS (but similar for cortisol). Serum DHEAS levels correlated with urinary DHEAS levels in HS and patients, whereby HS excreted 5-10 times more of this hormone than excreted by patients. Low serum levels of adrenal androgens and cortisol in patients as compared with HS were confirmed, and proteinuria was not associated with changes of measured renal parameters.

CONCLUSIONS

This study in patients with RA and SLE demonstrates that low serum levels of adrenal androgens and cortisol are not due to increased renal clearance and daily loss of these hormones. Decreased adrenal production or increased conversion or conjugation to downstream hormones are the most likely causes of inadequately low serum levels of adrenal hormones in RA and SLE.

Long-term anti-tumor necrosis factor antibody therapy in rheumatoid arthritis patients sensitizes the pituitary gland and favors adrenal androgen secretion

OBJECTIVE

New insights into the role of tumor necrosis factor (TNF) in the pathogenesis of rheumatoid arthritis (RA) have expanded our understanding about the possible mechanisms by which anti-TNF antibody therapy reduces local synovial inflammation. Beyond local effects, anti-TNF treatment may modulate systemic antiinflammatory pathways such as the hypothalamic-pituitary-adrenal (HPA) axis. This longitudinal anti-TNF therapy study was designed to assess these effects in RA patients.

METHODS

RA patients were given 5 infusions of anti-TNF at weeks 0, 2, 6, 10, and 14, with followup observation until week 16. We measured serum levels of interleukin-6 (IL-6), adrenocorticotropic hormone (ACTH), 17-hydroxyprogesterone (17[OH]progesterone), cortisol, cortisone, androstenedione (ASD), dehydroepiandrosterone (DHEA), and DHEA sulfate in 19 RA patients.

RESULTS

Upon treatment with anti-TNF, we observed a fast decrease in the levels of serum IL-6, particularly in RA patients who did not receive parallel prednisolone treatment (P = 0.043). In these RA patients who had not received prednisolone, the mean serum ACTH levels sharply increased after every injection of anti-TNF, which indicates a sensitization of the pituitary gland (not observed for the adrenal gland). During treatment, the ratio of serum cortisol to serum ACTH decreased, which also indicates a sensitization of the pituitary gland (P < 0.001), and which was paralleled by constant cortisol secretion. The adrenal androgen ASD significantly increased relative to its precursor 17(OH)progesterone (P = 0.013) and relative to cortisol (P = 0.009), which indicates a normalization of adrenal androgen production. The comparison of patients previously treated with prednisolone and those without previous prednisolone revealed marked differences in the central and adrenal level of this endocrine axis during long-term anti-TNF therapy.

CONCLUSION

Long-term therapy with anti-TNF sensitizes the pituitary gland and improves adrenal androgen secretion in patients who have not previously received prednisolone treatment. These changes are indicative of normalization of the HPA axis and must therefore be considered as evidence of an additional antiinflammatory influence of anti-TNF treatment in patients with RA.

Gas chromatography and high-performance liquid chromatography of natural steroids

This review article underlines the importance of gas chromatography (GC), high-performance liquid chromatography (HPLC) and their hyphenated techniques using mass spectrometry (MS) for the determination of natural steroids, especially in human biological fluids. Steroids are divided into eight categories based on their structures and functions, and recent references using the above methodologies for the analysis of these steroids are cited. GC and GC-MS are commonly used for the determination of volatile steroids. Although HPLC is a widely used analytical method for the determination of steroids including the conjugated type in biological fluids, LC-MS is considered to be the most promising one for this purpose because of its sensitivity, specificity and versatility.

Determination of natural corticosteroids in urine samples from sportsmen

A method for the determination of natural corticosteroids (cortisone, cortisol, 5beta-dihydrocortisone, 5beta-dihydrocortisol, tetrahydrocortisone and tetrahydrocortisol) found in the urine of sportsmen, was developed using a capillary gas chromatography-mass spectrometry ion trap system. 17alpha-Methyltestosterone was used as an internal standard. The different corticosteroids were determined from the peak area ratios of the [M]; [M-90] and [M-90-90] fragment ions of their methoxime-trimethylsiyl derivatives. Sensitivity (15 ppb), specificity, accuracy (96%) and reproducibility (RSD=4-10%) of the method were demonstrated to be satisfactory for measuring the urinary concentrations of the selected natural corticosteroids.

Optimization of the high-performance liquid chromatographic separation of a complex mixture containing urinary steroids, boldenone and bolasterone: application to urine samples

An HPLC separation of a complex mixture containing 13 urinary anabolics and corticoids, and boldenone and bolasterone (synthetic anabolics) has been carried out. The applied optimization method involved the use of binary, ternary and quaternary mobile phases containing acetonitrile, methanol or tetrahydrofuran as organic modifiers. The effect of different reversed-phase packings and temperature on the separation was studied. The optimum separation was achieved by using a water-acetonitrile (60:40, v/v) mobile phase in reversed-phase HPLC at 30 degrees C, allowing the separation of all the analytes in about 24 min. Calibration graphs were obtained using bolasterone or methyltestosterone as internal standards. Detection limits were in the range 0.012-0.107 microg ml(-1). The optimized separation was applied to the analysis, after liquid-liquid extraction, of human urine samples spiked with steroids.

Detection of exogenous intake of natural corticosteroids by gas chromatography/combustion/isotope ratio mass spectrometry: application to misuse in sport

A detailed procedure for the analysis of exogenous hydrocortisone and cortisone in urine by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) is proposed. As urinary levels of hydrocortisone are rather low for GC/C/IRMS analysis, the focus is on the main corticosteroid metabolites, tetrahydrocortisone (THE) and tetrahydrocortisol (THF). Following different solid phase extraction purifications, THE and THF are oxidized to 5beta-androstanetrione before analysis by GC/C/IRMS. Significant differences in delta(13)C per thousand values of synthetic natural corticosteroids and endogenous human corticosteroids have been observed. Therefore, a positive criterion, to detect exogenous administration of synthetic corticosteroids in anti-doping control, is proposed.

Optimization of separation of a complex mixture of natural and synthetic corticoids by micellar liquid chromatography using sodium dodecyl sulphate. Application to urine samples

A systematic optimization of the separation of a mixture of corticoids by micellar liquid chromatography, using sodium dodecyl sulphate as surfactant, a Hypersil (250 mm x 3.2 mm I.D.) C18 column, a flow-rate of 0.5 ml min(-1), and UV absorbance detection at 245 nm has been carried out. Several mobile phases consisting of sodium dodecyl sulphate and different organic modifiers were tested of which tetrahydrofuran, PrOH and BuOH were finally selected. On the basis of analysis time, resolution and number of compounds separated, a mobile phase containing 36 mM sodium dodecyl sulphate and 1.91% butanol allowed the separation of thirteen corticoids out of sixteen in about 27 min. Under these conditions the optimal concentration of sodium dodecyl sulphate was found to be 36 mM. A bivariant optimization method for the mobile phase BuOH-sodium dodecyl sulphate corrobored these results. The effects of temperature, ionic strength and flow-rate effect have also been studied. The most important analytical figures of merit were assessed and compared with those obtained using conventional mobile phases. The optimized method was applied to human urine samples of subjects administered with Dezacor (tablets containing 30 mg of the active ingredient deflazacort) with and without sample preparation.

Determination of urinary free cortisol by HPLC

We here report a reversed-phase HPLC method for the determination of free cortisol in human urine, using methylprednisolone as the internal standard. Before chromatography, samples were extracted with a C18 solid-phase extraction column and the steroids were separated on a LiChrospher 100 C18 column with a mobile phase of methanol/acetonitrile/water (43/3/54 by vol). Linearity, precision, and accuracy of the method were established. The detection limit was 10 pmol of cortisol, and total CVs were &lt;8%. With various solid-phase extraction columns the recovery of cortisol was 36–97%; recovery of the internal standard was 43–85%. Study of interference by 6 other steroids and metabolites and 24 drugs showed that carbamazepine and digoxin partly overlapped with cortisol, but this interference could be reduced by modification of the mobile phase. The HPLC method was compared with an RIA and an automated immunoassay method. The results obtained by HPLC averaged 40% of the RIA values.