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R Alfayate

Publications and source records attributed to R Alfayate.

6 recordsLinked to original sources
PubMed1999

Analytical and clinical evaluation of TSH and thyroid hormones by electrochemiluminescent immunoassays.

OBJECTIVES: To perform an analytical evaluation of the new electrochemiluminescent immunoassays (ECLIA) for TSH, FT4, and T3 in the Elecsys 2010 immunoassay system. To assess the clinical classification of patients under suspicion of thyroid disease based on these laboratory assays. MATERIALS AND METHODS: The analytical evaluation included the performance of minimum detectable concentrations, within-assay and inter-assay precision for the three analytes, functional sensitivity and linearity studies for TSH, and method comparison with the previous methods of RIA for FT4 and T3, and IRMA for TSH in current protocols of our institution. 102 patients with clinical suspicion of thyroid disease were assayed by ECLIA and radioactive techniques. Their differential clinical classification based on laboratory tests was studied as well. RESULTS: The minimum detectable concentrations coincided with the manufacturer's: <0.005 mU/L for TSH, <0.30 pmol/L for FT4, and <0.30 nmol/L for T3. Functional sensitivity for TSH was 0.044 mU/L. Over the analytical range tested, within-assay imprecision was below 3.2% for TSH, 2.2% for FT4 and 9.6% for T3, and interassay CVs were below 4.0% for TSH, 5.9% for FT4 and 12.9% for T3. Measurement of diluted sera showed the TSH assay to overestimate recoveries by 18.6%. We have compared sera results of the Elecsys ECLIA assays with those obtained from the IRMA (Spectria-Orion Diagnostica) for TSH: TSH (ECLIA) = 0.074+0.953 TSH (IRMA), (r = 0.974; Sy/x = 2.638), and RIA (Coat a Count-DPC) for FT4:FT4 (ECLIA) = 5.043+0.682 FT4 (RIA), (r = 0.770; Sy/x = 4.774) and RIA (Spectria-Orion Diagnostica) for T3: T3(ECLIA) = -0.461+1.084 T3 (RIA), (r = 0.970; Sy/x = 0.412). When sera from 102 patients were processed by both methods, minimal disagreement in the area of diagnostic classification was observed in 8/102 (7.8%) of the cases. CONCLUSION: The Elecsys 2010 is specially attractive as a routine assay because it is fully automated, obtaining results in only 18 minutes. The analytical assay performance for TSH, FT4 and T3 was shown to be acceptable. Using two different sets of diagnostic tests minimal discrepancies were found in the laboratory assessment for the classification of patients with clinical suspicion of thyroid disease.

Electrochemistry↗
PubMed1999

Insulin, androgens, and obesity in women with and without polycystic ovary syndrome: a heterogeneous group of disorders.

OBJECTIVE: To analyze the correlations among insulin, androgens, body mass index (BMI), and other related metabolic anomalies in women with and without polycystic ovary syndrome (PCOS). DESIGN: Retrospective study of normal and obese women with and without PCOS. SETTING: Gynecologic endocrinology units of Elche, San Juan, and Alicante Hospitals and Hormone Laboratory at Alicante University Hospital ("Miguel Hernández" University). PATIENT(S): A total of 212 women were studied: 137 with PCOS and 75 without PCOS. INTERVENTION(S): BMI, gonadotropins, insulin, androgens (T, androstenedione, DHEAS), 17alpha-hydroxyprogesterone, sex hormone-binding globulin, and triglycerides were studied. Glycemia and insulin response to the tolerance test (GTT) with a 100-g oral glucose load were also assessed in 103 women. RESULT(S): A good correlation between insulin and BMI was found in normal and obese women without hormonal dysfunction and in patients with or without PCOS. Good correlations, although lower, between insulin and T, and BMI, insulin, and T with triglycerides were also found in patients with PCOS. These patients fell into clearly distinct categories: with or without insulin resistance and with or without obesity, but slim women with PCOS had insulin and metabolic variables similar to those without PCOS, and most obese women with PCOS were insulin-resistant and more hyperandrogenic and hypertriglyceridemic. CONCLUSION(S): Insulin, androgens, and BMI are related in women both with PCOS and without PCOS, especially in obese ones. Insulin and metabolic indices are similar in lean women with PCOS and those without PCOS, but obese women with PCOS are more insulin-resistant, hyperandrogenic, and hypertriglyceridemic. Three types of disorders can be distinguished: simple nonhyperandrogenic obesity, typical nonhyperinsulinemic PCOS, and insulin-resistant PCOS.

17-alpha-Hydroxyprogesterone↗
PubMed1998

Influence of anti-insulin antibodies on insulin immunoassays in the autoimmune insulin syndrome.

The autoimmune insulin syndrome (AIS) is a rare, benign syndrome characterized by hyperinsulinaemia and hypoglycaemia associated with the presence of autoantibodies to insulin in patients who have not been treated with insulin. We report here the case of a 52-year-old patient with recurrent attacks of severe postprandial hypoglycaemia and we also present the effect of anti-insulin antibodies on insulin immunoassays. The patient was submitted to the following diagnostic tests: 5-h oral glucose tolerance test (OGTT), a prolonged 72-h fast and an insulin tolerance test (ITT). Serum glucose, total and free insulin, C-peptide, proinsulin, insulin antibodies and other autoantibodies were measured. Insulin concentrations were measured by two methods: a double antibody radioimmunoassay (RIA) and an immunoradiometric assay (IRMA). Insulin concentration measured by RIA was extremely high in the OGTT and 72-h fast. In contrast, insulin concentrations measured by IRMA were between 120 and 888 pmol/L in the OGTT and between 37 and 133 pmol/L during the 72-h fast. Fasting free-insulin concentrations measured by RIA were between 2224 and 2669 pmol/L, whereas free-insulin concentrations measured by IRMA ranged between 93 and 237 pmol/L. Total insulin concentrations measured by RIA and IRMA were 57,615 and 94,021 pmol/L, respectively. The C-peptide concentrations were moderately high in the three tests. Serum insulin antibody concentrations were extremely high (62-71%), compared with less than 3% in normal serum samples. In conclusion, the high insulin concentrations measured by RIA were caused by insulin autoantibodies. However, insulin concentrations measured by IRMA were not influenced by them. We conclude that IRMA is the more accurate method for measuring insulin concentrations in such cases.

Autoantibodies↗
PubMed1993

Usefulness of urinary growth hormone (GH) measurement for evaluating endogenous GH secretion in acromegaly.

We investigated the relationship between urinary growth hormone (u-GH) and spontaneous 24-hour plasma GH secretion in 15 acromegalic patients. To measure u-GH, we have developed a method based on concentrating the sample by centrifugal ultrafiltration and then performing an immunoradiometric assay using commercially available reagents. u-GH correlated well with the integrated concentration of plasma GH (r = 0.66, p < 0.02). Additionally, u-GH excretion in acromegalic patients was significantly higher than in the control group (190 +/- 100 vs. 3.89 +/- 0.56 pg/min, mean +/- SEM, p < 0.001). Immunoreactive u-GH showed the same elution pattern in Sephadex G-75 as standard or labeled hGH, proving that the substance measured in urine is authentic GH. In conclusion, u-GH appears to be a simple, noninvasive and inexpensive test for evaluating GH secretion in active acromegaly.

Acromegaly↗
PubMedDate not supplied

[Usefulness of RET proto-oncogene in the diagnosis of hereditary-type medullary carcinoma of the thyroid. Correlation with surgical findings].

In about 25% of cases medullary thyroid carcinoma (MTC) is hereditary. In this group is possible to detect germline point mutations of the RET proto-oncogene in about 95% of the studied cases. The purpose of the present paper is to confirm the value of the RET in the screening of the hereditary MTC. We studied 43 subjects at risk for a Multiple Endocrine Neoplasia Type 2A Syndrome. RET analysis was positive for MEN 2A in 22 subjects. Fifteen of the 22 have undergone a total thyroidectomy at our facility. Histopathological study of the surgical specimens confirmed the presence of a MTC in all the cases. According with our experience. RET analysis is a 100% sensitive and specific method of hereditary MTC screening, and we think it has obvious advantages over the calcitonin tests in technical, economic and ethic aspects.

Adolescent↗