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Biomedical subjects

H E Solberg

Publications and source records attributed to H E Solberg.

7 recordsLinked to original sources
PubMed1978

Optimum laboratory test combinations for thyroid function studies, selected by discriminant analysis.

In 430 patients with a variety of thyroid disorders, linear discriminant analysis was used to select laboratory test combinations giving optimum diagnostic efficiency in thyroid function studies. Unexpectedly, TSH was found valuable in the diagnosis of hyperthyroidism and T3 in hypothyroidism. These test combinations were found optimal for the separation of euthyroidism/hyperthyroidism: T3, TSH and T4; euthyroidism/hypothyroidism: Combined free thyroid hormone index (FTI) and TSH; and hyperthyroidism/euthyroidism/hypothyroidism: T3, TSH, T4, FTI and T3U. The latter test combination had a total efficiency of 94%. Cholesterol, achilles reflex time, PBI and radioiodine uptake measurement contributed little to the discrimination.

Adolescent↗
PubMed1978

Discriminant analysis.

Discriminant analysis (DA) is a pattern recognition technique that has been widely applied in medical studies. It allows multivariate observations ("patterns" or points in multidimensional space) to be allocated to previously defined groups (diagnostic categories). The relationships between DA and other multivariate statistical techniques of interest in medical studies will be briefly discussed. The main emphasis is on linear discriminant functions (LDF). The theoretic assumptions underlying DA using LDFs will be presented, and the effect of violations to these assumptions will be reviewed in detail. Alternative methods will be presented when violations cause serious problems. It has been shown that the familiar LDF is fairly robust to departures from the assumptions. The application of the LDF in less than ideal situations therefore often does not cause much harm (if the violations are not too grotesque). Another set of problems reviewed is how to estimate the misallocation probabilities when using discriminant functions. The selection of the "best" subset of variables out of the complete set will be discussed. Practical guide lines are given based on the theoretic studies reviewed. When possible, available computer programs for various problems of DA will be indicated. The review does not aim at covering all medical studies where DA has been applied, since emphasis is on the practical conclusions of the theory of DA.

Discriminant Analysis↗
PubMed1978

Bile acids measured in serum during fasting as a test for liver disease.

Total serum bile acids were estimated by an enzymic (3alpha-hydroxysteroid dehydrogenase) method in 173 fasting patients with different liver diseases, classified into 17 groups by morphological criteria. The results were not highly correlated with those for any of the other 24 tests included in the study, but moderate correlations were observed with bilirubin or alanine aminotransferase (positive) and with prealbumin (negative) in a few patient groups. The sensitivity of total bile acids in serum of fasting individuals as a liver-function test was rather high, comparable with that of serum enzymes. When discriminant analysis was used to identify optimal combinations of tests for the separation of different groups of liver diseases, we found that data on serum bile acids added some new information to that carried by the other 24 tests.

3-Hydroxysteroid Dehydrogenases↗
PubMed1975

Diagnosis of liver diseases by laboratory results and discriminant analysis. Identification of best combinations of laboratory tests.

Patients with different liver diseases were studied by discriminant analysis. Groups of patients classified mainly on the basis of liver biopsy findings showed functional differences which permitted a consistent reclassification by discriminant functions using laboratory results. Optimal combinations of laboratory tests for the separation of liver diseases were defined. Different combinations were found, dependent on the subsets of liver diseases studied.

Acute Disease↗