American journal of clinical pathology
-
A Lilliefors test of normality has been applied to data from precision and accuracy studies. Most data sets tested as non-normal. ⋯ The authors conclude that the selection of a test of normality requires careful study of the properties of the test. Otherwise, the subsequent choice between parametric and nonparametric statistics may not be meaningful.
-
Am. J. Clin. Pathol. · Nov 1978
Predictive values of erythrocyte indices for tests of iron, folic acid, and vitamin B12 deficiency.
The probabilities of low transferrin saturation, folic acid, or vitamin B12 levels in association with various erythrocyte indices was determined from the prevalences of these abnormalities and the distributions of the indices among 206 hospitalized and 1,000 ambulatory anemic patients. At mean corpuscular hemoglobin (MCH) greater than 30 pg, the probability of low transferrin saturation was 0.04 for hospitalized patients and 0.14 for ambulatory anemic patients. ⋯ The probabilities of low vitamin B12 or folic acid levels among hospitalized anemic patients were 0.0011 for mean corpuscular volume (MCV) less than 95 cu micron and 0.18 for MCV greater than or equal to 95 cu micron, indicating that measurements of these vitamins are of very limited value in most cases of anemia. These findings indicate that in some patients, the erythrocyte indices are sufficiently predictive for or against deficiency states to facilitate decisions regarding further diagnostic tests, as opposed to the increasing tendency to order such tests regardless of the indices.
-
A Task Force appointed by the College of American Pathologists studied the key elements that may affect a laboratory result, including the types of reagents, manufacturers of detection equipment, blanking procedures, calibrators, diluting and dispensing devices, and sample preparation. A field trial was conducted using cholesterol assay as the pilot study. ⋯ This report presents the preliminary findings of the field trial. Examples are shown to illustrate how obtaining additional information about how the laboratory test was performed led to identification of subtle differences in test results.
-
Am. J. Clin. Pathol. · Aug 1978
Decreased angiotensin-converting enzyme in the adult respiratory distress syndrome.
Using hippuryl-L-histidyl-L-leucine as substrate, serum angiotensin-converting enzyme was measured in 13 patients who had adult respiratory distress syndrome, eight patients with respiratory failure without adult respiratory distress syndrome, and two groups of controls: 24 healthy blood donors and 24 hospitalized patients with a variety of conditions but without respiratory failure or adult respiratory distress syndrome. Serum angiotensin-converting enzyme expressed in units/ml was 14.60 +/- 5.60 for adult respiratory distress syndrome compared with 28.92 +/- 6.60 for the blood donors, 20.76 +/- 5.87 for the patients with respiratory failure without adult respiratory distress syndrome and 20.20 +/- 5.94 in the hospitalized patients without respiratory failure or adult respiratory distress syndrome. These differences were significant, P less than .001 when adult respiratory distress syndrome was tested against the blood donors and P less than .01 against the other two groups. The significance of these findings is not clear, but the possibility is raised that the decrease of angiotensin-converting enzyme in adult respiratory distress syndrome results from a loss of pulmonary endothelial cells, which are known both to produce angiotensin-converting enzyme and to be damaged in adult respiratory distress syndrome.
-
A review of postmortem materials from two teaching hospitals, accumulated in a 14-year period (1962--1975), disclosed 63 patients with myocardial abscesses among 12,359 autopsies, an incidence of 0.5%. All 63 patients had multi-focal myocardial abscesses; the lesions were grossly discernible in six patients. Coexisting infective endocarditis was present in approximately 20% (12) of the 63 patients with myocardial abscesses. ⋯ Eighty-one per cent (51) of 63 patients had abscesses in one or more extracardiac organs. It appeared that most of the myocardial abscesses had resulted from disseminated sepsis. Surgical conditions, malignancy and alcoholic hepatic disease were the most frequent primary conditions in patients with myocardial abscesses.