An audit of total and free thyroxine measurements in screening for hypo and hyperthyroidism in patients using chemiluminescence immunoassay

An audit of 2509 patient specimens analyzed for both total thyroxine (TT4) and free thyroxine (FT4) by the ACS-180 automated chemiluminescence immunoassay analyzer revealed that there were 219 discrepancies (8.7% of the total). A discrepancy was defined as one analyte within its reference range and the other outside. The discrepant results were divided into 4 groups: group A: normal TT4, but decreased FT4, 101 patients (4.0%); group B: increased TT4, normal FT4, 78 patients (3.1%); group C: decreased TT4, normal FT4, 34 patients (1.4%); and group D: normal TT4, increased FT4, 6 patients (0.2%). TSH measurements were available, by a 3^rd generation chemiluminescent assay, in 142 of these patients, and were consistent with the FT4 result in 72 patients, with TT4 in 61 cases and with neither in 9 patients. The clinical diagnosis was investigated in a subgroup of 43 endocrine patients. Thirteen of the 20 endocrine patients in group A were diagnosed as hypothyroid, with a measured serum TSH, in 11 of them, of median 14.6, range 1.2 to 46.2 μlU/ml. Eleven of the 19 endocrine patients in group B were on thyroid replacement, with a measured serum TSH, in 7 of them of <0.01 μlU/ml. The audit of current laboratory practice led to a suggestion to replace the current thyroid function screening strategy of measuring both TT4 and FT4 by the combination of FT4 and TSH. The reasons for the discrepancies and the alternative strategies for screening of thyroid function are discussed.     

Fractals and the large-scale structure in the Universe

In Part 1 of this article, we had introduced the reader to some basic concepts of fractals and some operational algorithms to characterize them. We had also pointed out and clarified some common misconceptions about fractals. In this part we apply the fractal concepts to large-scale structures in the Universe. In particular we discuss the claim by some investigators that the distribution of galaxies in the Universe is a fractal. This is contrary to the standard view that the Universe is homogeneous and isotropic on large scales. Also discussed is the controversy as to whether the matter distribution in the Universe is a fractal on large-scales.     

Fractals and the large-scale structure in the Universe

During the last decade it has been argued by some investigators that the distribution of galaxies in the Universe is a fractal. This is contrary to the standard view that the Universe is homogeneous and isotropic on large scales. In this article, the basic concepts of fractals and their characterization are introduced with the help of simple examples. The applications of these concepts in the context of cosmology will be discussed in the second part. A K Mittal is currently a visiting scientist at Harish-Chandra Research Institute, Allahabad, on leave from the University of Allahabad. His research interests include chaos, fractals and their applications, partleularly in cosmology and in weather prodiction. T H Seshadri is at the Department of Physics and Astrophysics, University of Delhi. He is presently on lien from Harish-Chandra Research Institute, Allahabad. Areas of his interest include cosmic microwave background radiation, large scale structures in the Universe and application of fractals in these.     

The embedding theorems of Whitney and Nash

We begin by briefly motivating the idea of a manifold and then discuss the embedding theorems of Whitney and Nash that allow us to view these objects inside appropriately large Euclidean spaces.     

Predictive value of serum thyroglobulin in treated patients with differentiated thyroid carcinoma

An in-house radioimmuno assay for serum thyroglobulin was developed in our laboratory and compared its relative sensitivity with that of whole body scan in the detection of residual tumour or metastases and evaluated the predictive value of serum thyroglobulin in the clinical course of the disease. Ninety six patients after thyroidectomy were followed up for a maximum period of five years in this study. The sensitivity and specificity of serum thyroglobulin were found to be close to that of whole body scan (85% and 94% respectively). According to this study, a serum thyroglobulin >40 ng/ml can differentiate between patients with metastases and those in remission. Serum thyroglobulin can replace whole body scan during the subsequent follow-up if the patient had concordant whole body scan and serum thyroglobulin during initial assessment.     

Disseminating medical literature and knowledge in India in the 1980s: the SMLRT story

The informed netizen of today is in a state of information overload. With 785 million broadband subscribers and an urban and rural teledensity of 138% and 60%, respectively [1], India is already the second-largest online digital market. Today, in theory, medical journals and textbooks can be accessed by anyone, anytime, anywhere, and at affordable rates. Fifty odd years ago, when the authors entered medical school, the use of computers in medical education was unknown in India, as in other parts of the world. It was in this milieu, thirty-seven years ago, that eleven young Madras (Chennai)-based doctors decided to make medical literature easily accessible, particularly to clinicians in suburban and rural India. The aim was to make relevant, affordable reprints easily available to the practitioner at their place of work or study. Photocopying and using the postal service was the chosen, and indeed the only available, mode of operation. This article will outline the methodology used, trials and tribulations faced, and persistence displayed. At that time, the processes deployed appeared relevant and truly innovative. Over the ensuing years, developments in information technology made the services redundant. Extensive, even revolutionary, changes such as universal digitization and availability of a cost-effective Internet radically changed how medical literature could be accessed in India.