11ß-Hydroxysteroid dehydrogenase type-2 and type-1 (11ß-HSD2 and 11ß-HSD1) and 5ß-reductase activities in the pathogenia of essential hypertension.

Cortisol availability is modulated by several enzymes: 11ß-HSD2, which transforms cortisol (F) to cortisone (E) and 11ß-HSD1 which predominantly converts inactive E to active F. Additionally, the A-ring reductases (5α- and 5ß-reductase) inactivate cortisol (together with 3α-HSD) to tetrahydrometabolites: 5αTHF, 5ßTHF, and THE. The aim was to assess 11ß-HSD2, 11ß-HSD1, and 5ß-reductase activity in hypertensive patients. Free urinary F, E, THF, and THE were measured by HPLC-MS/MS in 102 essential hypertensive patients and 18 normotensive controls. 11ß-HSD2 enzyme activity was estimated by the F/E ratio, the activity of 11ß-HSD1 in compare to 11ß-HSD2 was inferred by the (5αTHF + 5ßTHF)/THE ratio and 5ß-reductase activity assessed using the E/THE ratio. Activity was considered altered when respective ratios exceeded the maximum value observed in the normotensive controls. A 15.7% of patients presented high F/E ratio suggesting a deficit of 11ß-HSD2 activity. Of the remaining 86 hypertensive patients, two possessed high (5αTHF + 5ßTHF)/THE ratios and 12.8% had high E/THE ratios. We observed a high percentage of alterations in cortisol metabolism at pre-receptor level in hypertensive patients, previously misclassified as essential. 11ß-HSD2 and 5ß-reductase decreased activity and imbalance of 11ß-HSDs should be considered in the future management of hypertensive patients.

Cortisol metabolism in the Bolivian squirrel monkey (Saimiri boliviensis boliviensis).

New World squirrel monkeys (Saimiri spp.) have high circulating cortisol levels but normal electrolytes and blood pressures. The goal of the present study was to gain insight into adaptive mechanisms used by Bolivian squirrel monkeys to minimize the effects of high cortisol on mineralocorticoid receptor (MR) activity and electrolyte and water balance. Aldosterone levels in serum from 10 squirrel monkeys were 17.7 +/- 3.4 ng/dl (normal range in humans, 4 to 31 ng/dl), suggesting that squirrel monkeys do not exhibit a compensatory increase in aldosterone. The squirrel monkey MR was cloned and expressed in COS-7 cells and found to have similar responsiveness to cortisol and aldosterone as human MR, suggesting that squirrel monkey MR is not inherently less responsive to cortisol. To determine whether altered metabolism of cortisol might contribute to MR protection in squirrel monkeys, serum and urinary cortisol and cortisone were measured, and a comprehensive urinary corticosteroid metabolite profile was performed in samples from anesthetized and awake squirrel monkeys. The levels of cortisone exceeded those of cortisol in serum and urine, suggesting increased peripheral 11beta-hydroxysteroid dehydrogenase 2 activity in squirrel monkeys. In addition, a significant fraction (approximately 20%) of total corticosteroids excreted in the urine of squirrel monkeys appeared as 6beta-hydroxycortisol, compared with that in man (1%). Therefore, changes in cortisol metabolism likely contribute to adaptive mechanisms used by Bolivian squirrel monkeys to minimize effects of high cortisol.

[Measurement of free urinary cortisol and cortisone using liquid chromatography associated with tandem mass spectrometry method]. / Dosagem de cortisol e cortisona livres urinários empregando cromatografia líquida associada a espectrometria de massa em tandem (LC-MS/MS).

Free urinary cortisol (UFF) measurement is one of the most useful screening tests for Cushing's syndrome. Immunoassays employed today by most clinical laboratories present limitations, specially concerning specificity. These limitations restrain a widespread application of the method, as well as the comparison of results obtained by the use of different methods. We present the development and characterization of a UFF and cortisone method based on liquid chromatography and tandem mass spectrometry (LC-MS/MS). A 200 microL aliquot from a 24 h urine sample is mixed with a solution containing a known quantity of deuterated cortisol and on-line extracted in solid phase (C18). The eluate is transferred to a second C18 column (Phenomenex Luna, 3 micro, 50 x 2 mm) and the isocratic mode elution profile is directly applied to a tandem mass spectrometer model Quattro Micro operating in positive mode atmospheric pressure chemical ionization (APCI). All process is automated and the quantification is performed by isotopic dilution, based on the analyte and the deuterated internal standard peak area ratios. The specificity study showed that all the steroids tested presented cross reactivity of <1% for cortisol and cortisone. Functional sensitivity is <1 microg/L for both steroids, and the interassay CV <8%. Recovery and linearity studies were satisfactory and comparison of results obtained using a RIA for UFF and the present method in 98 routine samples showed a correlation of r= 0.838, with the results obtained with LC-MS/MS significantly lower (medians of 22.0 vs. 49.4 microg/24 h for RIA) (P<0.0001). Reference values for cortisol were defined as values between 11 and 43 microg/24 h, compatible to those recently described for similar methods. The concomitant measurement of UF cortisone allows the study of the activity of the enzyme 11beta-HSD2 and the diagnosis of the apparent mineralocorticoid excess syndrome. The method represents the first steroid assay of a new generation, based on automated preparative methods and tandem mass spectrometry, described in our country.

Dosagem de cortisol e cortisona livres urinários empregando cromatografia líquida associada a espectrometria de massa em tandem (LC-MS/MS) / Measurement of free urinary cortisol and cortisone using liquid chromatography associated with tandem mass spectrometry method

A dosagem de cortisol livre na urina (CLU) é um método útil na triagem de pacientes suspeitos de síndrome de Cushing. Os imunoensaios atuais apresentam limitacões que dificultam sua aplicacão e a comparacão de resultados por diferentes ensaios. No presente método para dosagem de cortisol e cortisona livres urinários, baseado em cromatografia líquida com deteccão por espectrômetro de massa em tandem (LC-MS/MS), uma alíquota de urina 24h (200æL) é misturada com solucão contendo quantidade conhecida de cortisol deuterado e extraída on-line em fase sólida (C18). O eluato é transferido para uma segunda coluna C18 (Phenomenex Luna, 3æ, de 50 x 2mm), e o eluato obtido em modo isocrático é aplicado diretamente no MS/MS modelo Quattro Micro, operando no modo positivo de ionizacão química a pressão atmosférica (APCI). Todo o processo é automatizado e a quantificacão é feita por diluicão isotópica com base nas razões das áreas dos picos dos analitos e do padrão interno deuterado. O estudo de especificidade mostrou que nenhum esteróide testado apresenta reatividade cruzada superior a 1 por cento com cortisol ou cortisona. A sensibilidade funcional é <1æg/L para os dois esteróides, e o CV interensaio <8 por cento. Os estudos de recuperacão e de linearidade foram satisfatórios, e a comparacão entre os resultados obtidos para cortisol em 98 amostras de rotina, pelo ensaio em estudo e por um RIE, mostraram correlacão de r= 0,838, sendo os valores obtidos por LC-MS/MS significativamente mais baixos (medianas de 22,0 e 49,4æg/24h, respectivamente) (P<0,0001). Os valores de referência para cortisol foram definidos entre 11 e 43æg/24h, compatíveis com métodos semelhantes recentemente descritos. A dosagem concomitante de cortisona livre urinária permite o estudo da atividade da enzima 11beta-HSD2 e a pesquisa da síndrome do excesso aparente de mineralocorticóides. O método descrito representa a primeira descricão, em nosso meio, de uma nova geracão de métodos para a medida de esteróides hormonais, baseados em processos preparativos automatizados e leitura por espectrometria de massa em tandem.