Reference plasma adrenal steroid levels during early infancy are frequently used to verify hormone measurements when any adrenal abnormality is suspected. We aim to obtain longitudinal reference plasma levels for 17-hydroxyprogesterone (17OHP), 11-desoxycortisol (11DOC), cortisol, dehydroepiandrosterone sulfate (DHEAS), testosterone, and androstenedione in healthy infants from birth to 6 months of age. In 138 term infants, 80 males and 58 females, plasma steroid levels were measured using specific RIA procedures at birth and on the 3rd, 15th, 30th, 60th, 90th, 120th, 150th, and 180th days of life. Smoothed percentiles for each variable were calculated according to the LMS method (LMS program version 1.16, Institute of Child Health, London). Except for cortisol, plasma levels of adrenal steroids decreased progressively from birth to 6 months of age. Plasma concentrations of 17OHP, 11DOC, and cortisol did not show gender differences, but testosterone and androstenedione were significantly higher in boys, and DHEAS levels were higher in girls. Longitudinal reference plasma levels for 17OHP, 11DOC, cortisol, DHEAS, testosterone, and androstenedione have been described in an adequate sample of healthy infants from birth to 6 months of age. These standards, displayed as smoothed percentiles, may be used as reference values in the management of congenital endocrine (adrenal or gonadal) abnormalities that appear in the first weeks of life.

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Abstract.A comparative study of 3 analytical methods (immunoradiometric assay, enzyme immunometric assay, and chemiluminescent immunometric assay) for canine serum thyrotropin (TSH) was performed. Ninetysix dogs were included in the study. The within-and between-run precision was evaluated for each method, and correlations for the results obtained with each method were examined. The best within-and between-run precision was obtained with the chemiluminescent immunometric assay. Satisfactory correlations for the 3 analytical procedures were obtained but varied in relation to serum TSH concentration.Hypothyroidism is a common endocrinopathy in the dog. The diagnosis is based on the presence of typical clinical signs, results of thyroid function tests, and response to specific replacement therapy. The clinical signs are variable and nonspecific. 5 Thyroid function tests may be affected by many nonthyroidal factors or diseases. 1 Even response to therapy can be difficult to evaluate, particularly when other concurrent treatments have been instituted with thyroid hormone supplementation.Measurement of basal serum total thyroxine (TT4) has been frequently used in the evaluation of thyroid function, but the diagnostic value of a single low basal TT4 level has not been considered very useful. 8,9,11 For this reason, stimulation tests using thyroid-stimulating hormone (TSH, Thyrotropin) or thyroid-releasing hormone have been proposed. 4,7 Recently, an assay to measure canine TSH has been developed. Serum TSH is the most accurate test of thyroid function in humans. 12 Unfortunately, assay performance in the dog has been disappointing, and initial results have not been reliable when the measurement of canine TSH is the only assay performed. 3,6,8,10 However, further studies should be implemented, and most of the researchers agree that the assay could be helpful in the evaluation of hypothyroid dogs. 3,7,9,11,13 Three procedures can be used in the analysis of canine TSH: immunoradiometric assay, enzyme immunometric assay, and chemiluminescent immunometric assay. Most of the results published to date have been obtained with the immunoradiometric assay, and very little information about the other two methods is available. The aim of this study was to evaluate the analytical precision of the 3 methods and to compare the results obtained with each assay. Material and methodsAnimals. Blood samples were obtained from 96 dogs of different ages, sexes, and breeds from the Small Animal Internal Medicine Department at the Veterinary Faculty of the University of Zaragoza (Spain). Fasting blood samples were collected from the jugular vein of each dog into plain tubes. After coagulation, the samples were centrifuged (3,000 rpm for 10 min), and aliquots were stored at Ϫ20 C until analysis. The samples were stored for a maximum of 2 mo. Canine TSH has been shown to be stable for this period. 13 Analytical procedures. Serum canine TSH was evaluated in each sample by 3 commercially available methods. The manufacturers' instructions were fol...