[Analysis of an iodide radioimmunoassay for 11-deoxicortisol measurement]. / Análise de um radioimunoensaio iodado para determinação de 11-deoxicortisol.

OBJECTIVE: Our aim was to correlate 11-deoxycortisol levels obtained by two currently available techniques for 11-deoxycortisol measurement: radioimmunoassay, and high performance liquid chromatography followed by tandem mass spectrometry (MS/MS). The latter is the gold standard method for steroid hormone measurement. MATERIALS AND METHODS: We selected 88 samples and the results of these two methods were compared by Deming regression. RESULTS: The analytical sensitivity of the RIA was 0.30 ng/mL, with inadequate linearity and inadequate precision profile (34% of the samples had a CV ≥ 20%). From the selected samples, 54 had measurable levels of 11-deoxycortisol in both methods and were used in the comparison. The comparison of RIA with LC-MS/MS showed an overestimation of the results by RIA. The correlation coefficient was 0.610; linear regression slope was 3.751; and the intercept was 0.145, indicating a poor correlation between the two methods. CONCLUSION: We concluded that 11-deoxycortisol measured by radioimmunoassay, despite a good analytical sensitivity, showed very low specificity, precluding its use as a reliable method for 11-deoxycortisol measurement.

Análise de um radioimunoensaio iodado para determinação de 11-deoxicortisol / Analysis of an iodide radioimmunoassay for 11-deoxicortisol measurement

Objetivo : Nosso objetivo foi comparar duas técnicas de dosagem do 11-desoxicortisol: a técnica de radioimunoensaio iodado, a qual foi validada neste trabalho, e a cromatografia líquida de alta performance seguida por espectrometria de massa em tandem (LC-MS/MS), sendo a última considerada o padrão-ouro para dosagem dos hormônios esteroides. Materiais e métodos : Para a comparação entre os resultados de 11-desoxicortisol, foram selecionadas 88 amostras. Resultados : A sensibilidade analítica do radioimunoensaio foi de 0,30 ng/mL, com linearidade e perfil de precisão inadequado (34% das amostras com CV ≥ 20%). Das 88 amostras selecionadas, apenas 54 apresentaram resultados mensuráveis em ambos os métodos. A comparação desses resultados, por meio da regressão de Deming, resultou em um coeficiente de correlação de 0,610, inclinação de 3,751, intercepção de 0,145, evidenciando a pobre correlação entre os resultados e a superestimação dos resultados pelo RIA. Conclusão : Concluímos que o método de dosagem de 11-desoxicortisol por radioimunoensaio iodado apresentou resultados inadequados nos diversos parâmetros avaliados, inviabilizando sua utilização como método de dosagem do 11-desoxicortisol. Arq Bras Endocrinol Metab. 2014;58(3):232-6 .

Objective : Our aim was to correlate 11-deoxycortisol levels obtained by two currently available techniques for 11-deoxycortisol measurement: radioimmunoassay, and high performance liquid chromatography followed by tandem mass spectrometry (MS/MS). The latter is the gold standard method for steroid hormone measurement. Materials and methods : We selected 88 samples and the results of these two methods were compared by Deming regression. Results : The analytical sensitivity of the RIA was 0.30 ng/mL, with inadequate linearity and inadequate precision profile (34% of the samples had a CV ≥ 20%). From the selected samples, 54 had measurable levels of 11-deoxycortisol in both methods and were used in the comparison. The comparison of RIA with LC-MS/MS showed an overestimation of the results by RIA. The correlation coefficient was 0.610; linear regression slope was 3.751; and the intercept was 0.145, indicating a poor correlation between the two methods. Conclusion : We concluded that 11-deoxycortisol measured by radioimmunoassay, despite a good analytical sensitivity, showed very low specificity, precluding its use as a reliable method for 11-deoxycortisol measurement. Arq Bras Endocrinol Metab. 2014;58(3):232-6 .

O laboratório clínico livre de mercúrio / The clinical laboratory free of mercury

INTRODUÇÃO: No último século, os níveis de mercúrio no meio ambiente triplicaram, aumentado o risco de contaminação do ser humano. No ambiente, o mercúrio contamina os lençóis freáticos, bem como rios e mares e entra na cadeia alimentar pela ingestão de peixes contaminados. No organismo, afeta o sistema nervoso central (SNC). A exposição aguda, por inalação de vapores de mercúrio, acarreta astenia, fadiga, anorexia, perda de peso e perturbações gastrointestinais. O diagnóstico da contaminação é realizado pela análise em amostras de cabelo/sangue. A substituição dos equipamentos contendo mercúrio utilizados em serviços de saúde é procedimento fundamental para a redução dos riscos ocupacionais e ambientais. OBJETIVO: Descrever o processo de implantação do programa de "Mercúrio Zero" na Divisão de Laboratório Central do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (DLC/HC-FMUSP). MÉTODOS: O projeto foi desenvolvido em um período de três anos (2008-2010). Na elaboração do projeto, foram definidos planos de ações, incluindo um programa de treinamento e capacitação de uma equipe de trabalho responsável pela execução do processo de substituição dos equipamentos e reagentes. RESULTADOS: Ao final do projeto de implantação, a DLC/HC-FMUSP foi laureada com uma menção honrosa pelo programa Mercúrio Zero do Ministério do Trabalho e Emprego (MTE) por ter cumprido as exigências. CONCLUSÃO: Um ambiente laboratorial livre de mercúrio requer compromisso da alta direção e planejamento com ações consistentes, além de maturidade e conscientização de todos os colaboradores acerca do risco representado pelo mercúrioà saúde e ao meio ambiente.

INTRODUCTION: Over the last century, mercury levels in the environment have tripled, increasing the risk of human contamination. Hence, it pollutes groundwater, rivers and seas, and it enters the food chain through the ingestion of contaminated fish. It affects the central nervous system and the inhalation of mercury vapors cause asthenia, fatigue, anorexia, weight loss and gastrointestinal disturbances. The contamination detection is carried out through hair and blood sample analysis. The replacement of mercury-containing equipment used in health services is crucial in order to reduce environmental and occupational hazards. OBJECTIVE: To describe the implementation of "Zero Mercury" program at the Central Laboratory Division of University of São Paulo Medical School Hospital - CLD/USP-MSH (Divisão de Laboratório Central do Hospital das Clinicas da Faculdade de Medicina da Universidade de São Paulo [DLC/HC-FMUSP]). METHODS: The project was developed within the period of three years (2008-2010). During its elaboration, the action plans were defined, including a training program for the team responsible for the implementation of equipment and reagent replacement. RESULTS: By the end of the project, CLD/USP-MSH received an honorable mention by the Brazilian Ministry of Labor and Employment for the fulfillment of "Mercury Zero" program requirements. CONCLUSION: A mercury-free laboratory environment requires managerial commitment, a consistent action plan and staff awareness of health and environmental risks.

New mutation in the CASR gene in a family with familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT).

A loss of calcium-sensing receptor (CASR) function due to inactivating mutations can cause familial hypocalciuric hypercalcemia (FHH) or neonatal severe hyperparathyroidism (NSHPT). NSHPT represents the most severe expression of FHH and courses as a life-threatening condition. The aim of this study was to identify and characterize a CASR mutation in a female infant brought to the health service due to dehydration, apathy, lack of breast feeding and severe hypercalcemia. Molecular analysis was performed on genomic DNA of the index case and her parents. A novel homozygous mutation (p.E519X) in CASR was identified in the proband; both mother and father had the same mutation in heterozygous state, confirming their FHH condition. The mutation results in a truncated and inactive protein due to the lack of transmembrane and intracellular domains. The identification of this novel CASR gene mutation established the basis of hypercalcemia in this family and allowed a genetic counseling.

New mutation in the CASR gene in a family with familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT) / Nova mutação no gene CASR em uma família com hipercalcemia hipocalciúrica familiar (HHF) e hiperparatireoidismo neonatal grave (HPTNG)

A loss of calcium-sensing receptor (CASR) function due to inactivating mutations can cause familial hypocalciuric hypercalcemia (FHH) or neonatal severe hyperparathyroidism (NSHPT). NSHPT represents the most severe expression of FHH and courses as a life-threatening condition. The aim of this study was to identify and characterize a CASR mutation in a female infant brought to the health service due to dehydration, apathy, lack of breast feeding and severe hypercalcemia. Molecular analysis was performed on genomic DNA of the index case and her parents. A novel homozygous mutation (p.E519X) in CASR was identified in the proband; both mother and father had the same mutation in heterozygous state, confirming their FHH condition. The mutation results in a truncated and inactive protein due to the lack of transmembrane and intracellular domains. The identification of this novel CASR gene mutation established the basis of hypercalcemia in this family and allowed a genetic counseling.

Mutações inativadoras no gene do sensor do cálcio (CASR) podem causar hipercalcemia hipocalciúrica familiar (HHF) ou hiperparatireoidismo neonatal grave (HPTNSG). A HPTNS representa a forma mais grave da HHF cursando com risco de vida. O objetivo deste estudo foi identificar e caracterizar uma mutação no gene CASR de uma criança do sexo feminino levada ao hospital em decorrência de desidratação, apatia, dificuldade para mamar e hipercalcemia grave. A análise molecular foi realizada a partir do DNA genômico do caso índice e de seus pais. Uma nova mutação em homozigose (p.E519X) foi identificada no caso índice; ambos, mãe e pai, apresentaram a mesma mutação em heterozigose, o que os caracteriza como portadores de HHF. Essa alteração resulta em uma proteína truncada e inativa devido à falta dos domínios transmembrana e intracelular. A identificação dessa nova mutação estabeleceu a causa da hipercalcemia na família e permitiu o aconselhamento genético.