Thyroid stimulating hormone levels in cord blood are not influenced by non-thyroidal mothers' diseases

CONTEXT: Screening programs not only offer the opportunity to trace and treat almost all cases of congenital hypothyroidism but also mean large savings to the health system. However, carefully planned strategies are necessary to extend their benefits and reduce costs. OBJECTIVE: To determine the possible influence of maternal diseases that affect maternal-fetal placenta dynamics on primary thyroid stimulating hormone (TSH) screening for congenital hypothyroidism. DESIGN: Prospective non-randomized clinical trial with at least 3 months of follow-up. SETTING: A public university referral center [CAISM/Hospital das Clínicas, Faculty of Medicine, University of Campinas, Campinas, SP]. PARTICIPANTS: 415 neonates divided into 5 groups: eighty-three infants born from cardiac mothers; 98 from mothers that had toxemia; 54 of the mothers had diabetes mellitus; 40 were HIV positive and 140 had no diseases. INTERVENTION: All newborns had cord blood samples collected on filter paper at birth. MAIN MEASUREMENTS: TSH was measured from dried blood spots using a homemade immunofluorescence assay (sensitivity in dried blood spots = 0.1 mU/L). RESULTS: There was no significant difference in the mean TSH levels among the 5 groups. Moreover, TSH levels were around 5 mU/L in 48% of the newborns, indicating that our region is severely deficient in iodine. CONCLUSIONS: Our results indicate that primary TSH screening programs using cord blood are not affected by maternal diseases. We suggest that, besides its technical advantages over heel punctures with T4 primary approaches, neonatal screening using primary cord blood TSH may also be used as a monitoring tool for evaluation and control of iodine deficiency disorders (IDD).CONTEXTO: Os programas de detecção precoce trazem economias ao sistema de saúde e oferecem a oportunidade de rastrear e tratar precocemente casos de hipotiroidismo congênito. OBJETIVO: Determinar influências de doenças que afetam a dinâmica materno-fetal-placentária sobre programas de detecção precoce de hipotiroidismo congênito que se baseiam na dosagem do hormônio tirotrófico (TSH). TIPO DE ESTUDO: Ensaio clínico prospectivo não-randomizado com, ao menos, três meses de seguimento. LOCAL: Centro Universitário Público de Referência - Centro de Atendimento Integrado a Saúde da Mulher (CAISM). PARTICIPANTES: 415 recém-nascidos de 5 grupos de parturientes: 83 crianças eram filhas de mães cardiopatas; 98 de mães com toxemia gravídica; 54 de mães diabéticas; 40 de mães portadoras de imunodeficiência adquirida (HIV); e 140 de mães hígidas. PROCEDIMENTOS: Todos os recém-nascidos tiveram amostras de sangue de cordão umbilical coletadas em papel de filtro ao nascimento. VARIÁVEIS ESTUDADAS: Dosagem de TSH em sangue coletado em papel de filtro usando um ensaio imunofluorométrico próprio (sensibilidade em manchas de sangue seco = 0.1 mU/L). RESULTADOS: Não encontramos diferença na média de TSH dos 5 grupos. Além disso, os níveis de TSH estavam acima de 5 mU/L em 48% dos bebês, sugerindo que nossa região é severamente deficiente em iodo. CONCLUSÕES: Nossos resultados demonstram que programas de detecção precoce de hipotiroidismo congênito, que utilizam primariamente TSH, não são afetados por doenças maternas não-tiroidianas. Sugerimos que, além das vantagens técnicas sobre a punção de calcanhar com dosagem primária de T4, os programas de detecção precoce que utilizam primariamente TSH de cordão umbilical também podem ser usados como instrumento de avaliação e controle da carências de iodo.State University of Campinas Faculty of Medical Sciences Department of MedicineUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Department of MedicineUNIFESP, EPM, Department of MedicineSciEL

Evolução dos ensaios para paratormônio

PTH metabolism is complex and the circulating forms include the intact 1-84 molecule as well as several carboxyl-terminal fragments. The first generation of PTH assays included several types of competitive assays, with specificities that spanned carboxyl, mid-region and amino-terminal portions of the molecule. The limitations of these assays and the methodological evolution led to the description of 2nd generation non-competitive immunometric assays for PTH in the late 80's, based on the recognition of the PTH molecule by two different antibodies, one directed against de amino-terminal and other against the carboxyl-terminal segments. The observation that in some circumstances long carboxyl-terminal segments were also measured by 2nd generation assays led to the development of 3rd generation assays based on amino-terminal specific antibodies that are specific for the first amino acids, measuring only the molecular forms that activate PTH1R. The practical and cost-benefit advantages of these assays are still debatable. The recent observation that carboxyl-terminal fragments of PTH have biological activity via a distinct receptor than PTH1R, points to the future need of more than one assay in order to evaluate parathyroid hormone function.O metabolismo do PTH e complexo e as formas circulantes incluem o PTH 1-84, assim como fragmentos C-terminal. A primeira geração de ensaios para o PTH incluía vários ensaios competitivos com especificidades para as regiões carboxi, meio da molécula e amino-terminal. A limitação destes ensaios e a evolução metodológica, levaram ao desenvolvimento dos ensaios não competitivos de 2ª. geração no final dos anos 80, baseados no reconhecimento por dois anticorpos diferentes, contra a porção amino e carboxi-terminal respectivamente. A observação que em algumas circunstâncias segmentos carboxiterminais longos também eram detectados, levou ao desenvolvimento dos ensaios de 3ª. geração, baseados em anticorpos específicos para a porção aminoterminal com maior especificidade para os primeiros aminoácidos, e assim mensurando apenas a forma molecular que ativa o PTH1R. As vantagens práticas e o custo-benefício deste ensaio ainda e motivo de debate. A observação recente de que fragmentos carboxiterminais têm atividade biológica via receptor distinto, aponta para a necessidade futura de mais de um ensaio para avaliar a função do paratormônio.Laboratorio FleuryUniversidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Division of EndocrinologyUNIFESP, EPM, Division of EndocrinologySciEL

Body fat and cholecalciferol supplementation in elderly homebound individuals

Vitamin D deficiency, observed mainly in the geriatric population, is responsible for loss of bone mass and increased risk of bone fractures. Currently, recommended doses of cholecalciferol are advised, but since there are few studies evaluating the factors that influence the serum levels of 25-hydroxyvitamin D (25(OH)D) following supplementation, we analyzed the relationship between the increase in serum 25(OH)D after supplementation and body fat. We studied a group of 42 homebound elderly subjects over 65 years old (31 women) in order to assess whether there is a need for adjustment of the doses of cholecalciferol administered to this group according to their adipose mass. Baseline measurements of 25(OH)D, intact parathyroid hormone and bone remodeling markers (osteocalcin and carboxy-terminal fraction of type 1 collagen) were performed. Percent body fat was measured by dual-energy X-ray absorptiometry. The patients were divided into three groups according to their percent body fat index and were treated with cholecalciferol, 7,000 IU a week, for 12 weeks. The increases in serum levels of 25(OH)D were similar for all groups, averaging 7.46 ng/mL (P < 0.05). It is noteworthy that this increase only shifted these patients from the insufficiency category to hypovitaminosis. Peak levels of 25(OH)D were attained after only 6 weeks of treatment. This study demonstrated that adipose tissue mass does not influence the elevation of 25(OH)D levels following vitamin D supplementation, suggesting that there is no need to adjust vitamin D dose according to body fat in elderly homebound individuals.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Disciplina de EndocrinologiaUNIFESP, EPM, Disciplina de EndocrinologiaSciEL

Increases in summer serum 25-hydroxyvitamin D (25OHD) concentrations in elderly subjects in São Paulo, Brazil vary with age, gender and ethnicity

<p>Abstract</p> <p>Background</p> <p>Hypovitaminosis D is a common condition among elderly individuals in temperate-climate countries, with a clear seasonal variation on 25 hydroxyvitamin D levels, increasing after summer and decreasing after winter, but there are few data from sunny countries such as Brazil. Many factors can interfere on vitamin D cutaneous synthesis. We aimed at studying the 25OHD variations during winter and summer in an outdoor physically active elderly population living in São Paulo city, and analysed their determining factors.</p> <p>Methods</p> <p>Ninety-nine individuals (52 women and 47 men, from 55 to 83 years old) from different ethnic groups were selected from an outdoor physical activity group. Data are reported as Mean ± SD, and we used Pearson Linear Correlation, Student's t-test for non-related samples, Chi-square (χ²) test and One-way ANOVA for analysis.</p> <p>Results</p> <p>Mean 25OHD value for the whole group was 78.9 ± 30.9 nmol/L in the winter and 91.6 ± 31.7 nmol/L in the summer (p = 0.005). Mean winter serum 25OHD concentrations were not different between men and women (81.2 ± 30.1 nmol/L vs. 76.7 ± 31.8 nmol/L, respectively), and 19.2% of the individuals showed values < 50 nmol/L. In the summer, we noticed an increase only for men (107.6 ± 31.4 nmol/L) compared to women (76.7 ± 24.0 nmol/L), and 6.5% showed values < 50 nmol/L. A decrease in the mean PTH in the summer compared to the winter was noticed, with PTH levels showing a relationship with 25OHD concentrations only in the winter (r = -0.208, p = 0.041). White individuals showed an increase in mean serum 25OHD in the summer (p = 0.016) which was not noticed for other ethnic groups (Asians, native Brazilians and blacks). An increase in 25OHD values in the summer was observed in the age groups ranging from 51-60 and 61-70 years old (p < 0.05), but not in the age group from 71 years old on.</p> <p>Conclusions</p> <p>25OHD values increased during the summer in elderly residents of São Paulo, but to different extents depending on ethnicity, gender and age. This season-dependent increase was noticed only among men, white and who were in the youngest group of individuals.</p

Heterogeneidade das formas carboxi-terminal circulantes de paratormônio em pacientes com hiperparatiroidismo devido à insuficiência renal crônica terminal

OBJECTIVE: To study carboxyl-terminal (COOH) parathyroid hormone (PTH) circulating forms in patients with hyperparathyroidism due to end stage renal disease (ESRD). METHODS: An immunometric assay that recognizes both intact and COOH PTH forms was developed. The assay, in conjunction with an intact assay, was used to measure PTH in serum samples obtained from 25 patients with hyperparathyroidism due to ESRD. Samples were also submitted to gel filtration chromatography in a Superdex® 30 1.6 x 60 cm column, and the PTH content in the elution tubes, measured using both assays. RESULTS: Values from 39.000 to 232.300 ng/mL (mean ± sd = 101.680 ± 45.330 ng/mL) were found using the COOH assay (PTH 39-84 was used as standard). Values obtained by the intact PTH assay ranged from 318 to 3.307 ng/mL (1.769 ± 693 ng/mL) with a correlation between assays of 0.462 (p = 0.02). The elution profile obtained using the COOH assay showed a preponderance of forms with MW ranging from 8.500 to 4.500 daltons. The profiles obtained from the 25 patients were very similar. CONCLUSIONS: In patients with hyperparathyroidism due to ESRD circulating PTH levels contain a broad range of molecular forms including COOH with MW ranging from 8.500 to 4.500 daltons. These forms are not recognized by the standard intact PTH assays. The correlation of these findings to the clinical aspects of bone disease in ESRD patients remains to be studied.OBJETIVO: Estudar as formas carboxi-terminal (COOH) circulantes de paratormônio (PTH) em pacientes com hiperparatiroidismo devido à insuficiência renal crônica (IRC) terminal. MÉTODOS: Foi desenvolvido um ensaio imunométrico que reconhece formas intactas e COOH longas de PTH. Esse ensaio foi utilizado, em conjunto com um ensaio para molécula intacta de PTH, em amostras de 25 pacientes com hiperparatiroidismo devido à IRC. As amostras também foram submetidas à cromatografia de gel filtração em coluna de Superdex® 30 de 1,6 x 60 cm, e o conteúdo de PTH nos tubos de eluato foi medido, empregando-se os dois ensaios. RESULTADOS: Valores entre 39.000 e 232.300 ng/mL (média ± dp = 101,680 ± 45,330 ng/mL) foram obtidos usando-se o ensaio COOH (PTH 39-84 foi utilizado como padrão). Com o ensaio para PTH intacto, os valores distribuíram-se entre 318 e 3,307 ng/mL (1,769 ± 693 ng/mL) com correlação entre ambos de 0,462 (p = 0,02). O perfil cromatográfico obtido com o ensaio COOH mostrou predomínio de formas com PM entre 8.500 e 4.500 daltons. Os perfis cromatográficos dos 25 pacientes foram bastante semelhantes. CONCLUSÕES: Em pacientes com hiperparatiroidismo devido à IRC, os níveis circulantes de PTH contêm um espectro de formas moleculares que incluem formas carboxi-terminais, com PM entre 8.500 e 4.500 daltons. Essas formas não são reconhecidas pelos ensaios de rotina utilizados para a medida de PTH intacto. A correlação entre esses achados e os aspectos clínicos da doença óssea em pacientes com IRC necessita de maiores estudos.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de MedicinaUNIFESP-EPM Departamento de MedicinaUNIFESP, EPM, Depto. de MedicinaUNIFESP, EPM Depto. de MedicinaSciEL

Correlation between urinary iodine levels and TSH of umbilical cord from newborns of the University Hospital at the School of Medicine from Ribeirão Preto, São Paulo

The safest and most efficient way to diagnose congenital hypothyroidism (CH) is through screening programs using serum thyroid stimulating hormone (TSH). CH occurs in one in 1:2,300 - 1:5,000 births but higher rates are found in iodine-deficient areas. Iodine was measured in the urine of 141 newborns (87 males and 54 females) from Ribeirão Preto to complement the screening program developed by the School of Medicine of Ribeirão Preto (FMRP-USP) and Federal University of São Paulo (UNIFESP). TSH values did not disclose any case of CH, although we have seen an elevated ratio (0.96%) of calls for retests. The iodine urinary levels ranged from 2.1 to 194µg/l (mean 58.3±36.2µg/l). No differences between the levels of urinary iodine and gender or gestational ages were observed. A negative correlation between urinary iodine and TSH of blood from umbilical cord was found (r= -0.20, p= 0.02).A forma mais eficaz e segura de se diagnosticar o hipotireoidismo congênito (HC) é através dos programas de rastreamento neonatal com dosagens sanguíneas do hormônio tireotrófico (TSH). Está estabelecido que a incidência de HC varia entre 1:2.300 - 1:5.000 nascimentos, sendo mais elevada em áreas de carência iódica. Complementando o programa de rastreamento para HC desenvolvido entre a Faculdade de Medicina de Ribeirão Preto (FMRP-USP) e a Universidade Federal de São Paulo (UNIFESP), dosou-se iodo em amostras urinárias de 141 recém-nascidos (RN) de Ribeirão Preto, sendo 87 meninos e 54 meninas. Os resultados de TSH não indicaram casos de HC, embora um elevado número de crianças (0,96%) tenha sido convocado para novos testes. As iodúrias variaram entre 2,1 e 194µg/l, (média de 58,3±36,2µg/l). Não foram observadas diferenças entre os valores de iodo urinário dos RN segundo o sexo ou idade gestacional. Foi encontrada correlação negativa entre iodúria e TSH de sangue de cordão umbilical (r= -0,20, p= 0,02).Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade de São Paulo Faculdade de Medicina Hospital das ClínicasUniversidade Federal de São Paulo (UNIFESP) Departamento de Medicina Disciplina de EndocrinologiaUNIFESP, Depto. de Medicina Disciplina de EndocrinologiaSciEL

Efeitos da retirada do uso prolongado de alendronato na prática clínica

OBJECTIVE: To assess bone turnover markers (BTM) and bone mineral density (BMD) after discontinuation of alendronate treatment used for five or more years. SUBJECTS AND METHODS: 40 patients (pt) with post-menopausal osteoporosis treated with alendronate (10 mg/d) for at least five years (Group 1, G1) had their medication discontinued. Group 2 (G2): 25 pt treated with alendronate for at least one year. Group 3 (G3): 23 treatment-naïve osteoporotic pt. BMD was evaluated in G1 and G2 at baseline and after 12 months. Collagen type I cross-linked C-telopeptide (CTX) and procollagen type 1 N-terminal propeptide (P1NP) levels were measured in all pt at baseline, and in G1 and G2 every three months for 12 months. Data were analyzed using ANOVA on ranks and Mann-Whitney tests. RESULTS: Mean BMD values in G1 and G2 did not differ during follow-up. However, 16 pt (45.7%) in G1 and one (5.2%) in G2 lost BMD (P < 0.001). BTM at baseline was not different between G1 and G2, and both were lower than G3. A significant increase in BTM levels was detected in G1 pt after three months, but not in G2. CONCLUSION: Observed BMD loss and BTM rise after alendronate withdrawal imply that bone turnover was not over suppressed, and alendronate discontinuation may not be safe.OBJETIVO: Avaliar a evolução dos marcadores de metabolismo ósseo (MMO) e da densidade mineral óssea (DMO) após cinco anos de uso de alendronato em mulheres osteoporóticas na pós-menopausa. SUJEITOS E MÉTODOS: 40 pacientes (pct) osteoporóticas, na pós-menopausa, em uso de alendronato (10 mg/dia) por pelo menos 5 anos (Grupo 1 − G1) tiveram o uso do bisfosfonato suspenso. O grupo 2 (G2): 25 mulheres na pós-menopausa, em uso de alendronato (10 mg/dia) há pelo menos 1 ano. Grupo 3 (G3): 23 pct osteoporóticas, controles ainda sem tratamento. G1 e G2 submeteram-se à avaliação da DMO por DXA (basal e após 12 meses de seguimento). Todas as pct colheram amostras basais de CTX e P1NP, e G1 e G2 submeteram-se a coletas trimestrais de CTX e P1NP durante 1 ano. Resultados foram analisados por ANOVA on ranks e Mann-Whitney. RESULTADOS: Níveis médios de DMO não variaram em G1 ou G2 durante o estudo; no entanto, 16 pct (45,7%) no G1 e 1 pct (5,2%) no G2 apresentaram redução clinicamente significativa de DMO (P < 0,001). Níveis basais de CTX e P1NP não diferiram entre G1 e G2, com ambos inferiores aos níveis de G3. Em G1, observou-se elevação significativa de CTX e P1NP após 3 meses. Os níveis de CTX e P1NP em G2 permaneceram estáveis durante todo o seguimento. CONCLUSÃO: Não parece haver supressão excessiva do metabolismo ósseo na prática clínica. A suspensão temporária do alendronato após seu uso prolongado pode não ser segura.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaFleury InstituteUNIFESP, EPMSciEL

Development of a semi-automated method for measuring urinary iodine and its application in epidemiological studies in Brazilian schoolchildren

In this study we developed a semi-automated method for the measurement of urinary iodine using firstly ammonium persulfate for digestion of urine followed by estimation of iodine content in the Sandell-Kolthoff reaction, in which iodine acts as a catalyst for the reduction of cerium. This method was validated in the 3rd Brazilian National Survey of iodine deficiency in 1994. We studied 16,803 casual urine samples from schoolchildren of 401 cities and found 4 moderately-deficient towns (Almas, Arraias, and Parana, in the State of Tocantins, and Cocos, in the State of Bahia), and 116 mildly-deficient. This work suggests that despite the salt iodization program, there was some iodine-deficient areas in Brazil in 1994. Recent surveys, involving less cities, are indicating an excess of iodine ingestion. Therefore, in a country of continental dimensions and very heterogeneous in terms of public health, periodical evaluations are necessary to monitor the real situation of iodine nutrition in Brazil. the method developed in this paper is suitable for these surveys.Univ Estadual Maringa, Dept Med, Ctr Ciencias Saude, Maringa, Parana, BrazilUniversidade Federal de São Paulo, Mol Endocrinol Lab, Disciplina Endocrinol, Dept Med,Escola Paulista Med, BR-04032029 São Paulo, BrazilUniversidade Federal de São Paulo, Mol Endocrinol Lab, Disciplina Endocrinol, Dept Med,Escola Paulista Med, BR-04032029 São Paulo, BrazilWeb of Scienc

Factors affecting vitamin D status in different populations in the city of São Paulo, Brazil: the São Paulo vitamin D Evaluation Study (SPADES)

Background: Hypovitaminosis D is a common condition among elderly individuals in temperate-climate countries, with a clear seasonal variation on 25 hydroxyvitamin D [(25(OH)D] levels, increasing after summer and decreasing after winter, but there are few data from sunny countries such as Brazil. We aimed to evaluate 25-hydroxyvitamin D concentrations and its determining factors, in individuals in the city of São Paulo belonging to different age groups and presenting different sun exposure habits.Methods: 591 people were included as follows: 177 were living in institutions (NURSING HOMES, NH, 76.2 +/- 9.0 years), 243 were individuals from the community (COMMUNITY DWELLINGS, CD, 79.6 +/- 5.3 years), 99 were enrolled in physical activity program designed for the elderly (PHYSICAL ACTIVITY, PA, 67.6 +/- 5.4 years) and 72 were young (YOUNG, 23.9 +/- 2.8 years). Ionized calcium, PTH, 25(OH)D, creatinine and albumin were evaluated. ANOVA, Mann-Whitney and Kruskal Wallis tests, Pearson Linear Correlation and Multiple Regression were used in the statistical analysis.Results: 25(OH)D mean values during winter for the different groups were 36.1 +/- 21.2 nmol/L (NH), 44.1 +/- 24.0 nmol/L (CD), 78.9 +/- 30.9 nmol/L (PA) and 69.6 +/- 26.2 nmol/L (YOUNG) (p < 0.001) while during summer they were 42.1 +/- 25.9 nmol/L, 59.1 +/- 29.6 nmol/L, 91.6 +/- 31.7 nmol/L and 103.6 +/- 29.3 nmol/L, respectively (p < 0.001). the equation which predicts PTH values based on 25(OH)D concentration is PTH = 10 + 104.24.e(-(vitD-12.5)/62.36) and the 25(OH)D value above which correlation with PTH is lost is 75.0 nmol/L. in a multiple regression analysis having 25(OH)D concentration as the depending variable, the determining factors were PTH, ionized calcium and month of the year (p < 0.05).Conclusions: Much lower 25(OH)D values were found for the older individuals when compared to younger individuals. This finding is possibly due to age and habit-related differences in sunlight exposure. the existence of seasonal effects on 25(OH)D concentration throughout the year was evident for all the groups studied, except for the nursing home group. According to our data, PTH values tend to plateau above 75 nmol/L.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo UNIFESP, Escola Paulista Med, Dept Med, Div Endocrinol, Sao Carlos, SP, BrazilUNIFESP, Dept Geriatr Med, Sao Carlos, SP, BrazilUNIFESP, Dept Prevent Med, Sao Carlos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, Escola Paulista Med, Dept Med, Div Endocrinol, Sao Carlos, SP, BrazilUNIFESP, Dept Geriatr Med, Sao Carlos, SP, BrazilUNIFESP, Dept Prevent Med, Sao Carlos, SP, BrazilFAPESP: 03/13194-6Web of Scienc

Parathyroid hormone values obtained with immunometric assays depend on the amino-terminal antibody specificity

Introduction of 2nd generation immunometric assays for the measurement of serum parathyroid hormone (PTH), turned them more available, simple and rapid. These methods, based on double identification of the PTH molecule, supposedly measure the intact, bioactive molecule, with the sequence 1-84. Recent works showed that they also measure forms with amino-terminal deletions, like the 7-84 form, which are not able to activate the traditional PTH receptor (PTH1R). Thus, an important practical aspect is the definition of the PTH forms measured by the immunometric assays, a fact that depends on the specificity of the antibodies employed. In this report we compare the results obtained with an in-house immunofluorometric assay that presents a cross-reactivity of 50% with the 7-84 PTH sequence, and two commercial 2nd generation assays, that react 100%. In a first study, 135 samples were measured using our assay and an electrochemiluminescent assay, resulting in a correlation coefficient of 0.961 (P<0.0001) and medians of 35.0 and 51.0ng/L (P<0.0001). In a second study, 252 samples were analyzed using our assay and an immunochemiluminometric assay, resulting in a correlation of 0.883 (P<0.0001) and medians of 36.0 and 45.5ng/L (P<0.0001). In both studies results obtained with the in-house assay were significantly lower, as expected by the specificity of the anti-amino-terminal antibody employed. Our data support the need of a precise description of the specificity of the amino-terminal antibodies employed in 2nd generation PTH assays in order to better compare results and define normal ranges.A introdução de ensaios imunométricos (EIM) de 2ª geração, tornaram a medida de paratormônio (PTH) sérico mais disponível, simples e rápida, aumentando sua utilização. Esses métodos, baseados em dupla identificação da molécula de PTH, mediriam supostamente a molécula intacta, bioativa, de seqüência 1-84. Recentes trabalhos mostraram que eles também medem formas com deleções amino-terminais, como a forma 7-84, que não ativam o receptor tradicional de PTH (PTH1R). Em função disto, um aspecto prático importante é a definição das formas de PTH medidas pelos EIM, sendo que estas dependem da especificidade dos anticorpos empregados. Neste trabalho, comparamos um ensaio imunofluorométrico por nós desenvolvido, que apresenta reatividade cruzada de 50% com a seqüência 7-84 do PTH, com dois ensaios comerciais de 2ª geração, que reagem 100%. Numa 1ª. comparação, 135 amostras de soro foram dosadas com o nosso ensaio e com um ensaio eletroquimioluminescente, obtendo-se uma correlação de 0,961 (P<0,0001) e medianas de 35,0 e 51,0ng/L (P<0,001). Numa 2ª. comparação, 252 amostras foram dosadas com nosso ensaio e com um ensaio imunoquimioluminométrico, obtendo-se uma correlação de 0,883 (P<0,0001) e medianas de 36,0 e 45,5ng/L (P<0,0001). Em ambos os casos, os dados obtidos com nosso ensaio foram significativamente mais baixos, dados condizentes com a especificidade do anticorpo amino-terminal empregado. Nossos dados reiteram a necessidade de descrição precisa da especificidade dos anticorpos amino-terminais empregados em ensaios de PTH de 2ª geração, de maneira a melhor comparar resultados e definir faixas de normalidade.Instituto FleuryUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL