The assessment of interpretation in clinical biochemistry: a personal view.

In many laboratories, clinical biochemists add interpretative comments to laboratory reports. There is, however, little evidence base to support this activity. Interpretative comments attached to reports are quite complex, usually consisting of several components that may suggest possible diagnoses and additional tests.

Provision of interpretative comments on biochemical report forms.

Providing interpretative comments on reports, particularly those for primary care physicians is an important part of our job. Few clinical biochemists (whether medical or scientific) receive significant training for this. Most work in isolation, and few receive feedback on the utility of their comments.

Experience with assessing the quality of comments on clinical biochemistry reports.

We assess a previously described scoring system for the appropriateness of interpretative comments on clinical biochemistry reports over 21 distributed cases and over a group of 41 UK-based participants. The distributed cases covered a range of clinical scenarios and included pre- and post-analytical problems. The UK-based participants had all registered an interest in using this case participation for their continuing professional development; all had higher professional qualifications in clinical biochemistry, and the group included participants based in teaching hospitals and district general hospitals as well as those with a medical or a scientific background.

Assessing the quality of comments on reports: a retrospective study.

I describe a comparatively simple method for assessing the quality of comments on clinical biochemistry reports. It is based on independent peer review of components of comments, appears reasonably robust and correlates well with separate independent assessment of the value of complete comments. The method gives a numerical score, and thus lends itself to a wide range of statistical manipulations and assessment for education and audit purposes.

Effect of hemicholinium-3 on the hypothalamic concentration of a cytochemically detectable glucose-6-phosphate dehydrogenase-stimulating substance.

Hypothalamus and plasma of salt-loaded rats, spontaneously hypertensive rats (SHR), and hypertensive reduced renal mass rats (RRM), and the plasma of patients with essential hypertension and of Milan hypertensive rats contain an increased concentration of a cytochemically detectable glucose-6-phosphate dehydrogenase (G6PD)-stimulating substance that has properties similar to that of a possible choline derivative di-methyl methylene immonium ion. Intracerebroventricular (i.c.

Distribution of haemoglobin in patients presenting to their general practitioner, and its correlation with serum ferritin.

We have conducted a survey in the United Kingdom in order to evaluate the prevalence of anaemia and of iron deficiency in elderly male and female patients and in female patients of child-bearing age presenting to their general practitioner. Although haemoglobin values were approximately normally distributed, there was evidence of a bimodal distribution of serum ferritin values, particularly in elderly men. A correlation between serum ferritin and haemoglobin values was found to exist, both in the elderly and in younger women.

Effect of outlying standard points on curve fitting in radioimmunoassay.

Outlying points often appear in standard curves for radioimmunoassay. We have examined the effect of outlying standard points on the ability of various automated data-processing routines, and of manual operators, to position a radioimmunoassay standard curve correctly. Manual operators were found to be highly subjective in their handling of a standard curve containing outlying points.

Three different radioiodination methods for human spleen ferritin compared.

We compared three different methods for radioiodination of human spleen ferritin. Tracers prepared by direct oxidative iodination with use of Chloramine T or 1,3,4,6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril (Iodogen) were structurally altered by the labeling procedure, as was made apparent by gel filtration and electrophoresis on polyacrylamide gel. Tracers prepared by conjugation to radioiodinated N-succinimidyl-6-(4-hydroxyphenyl)propionate retained their structural integrity, as assessed by physicochemical methods.

Thyroidal hormone metabolism in obesity during semi-starvation.

Six obese subjects were studied over a period of 12 weeks whilst on a 1260 kJ (300 kcal) formula diet. Weight loss was initially rapid, but later slowed markedly despite good patient compliance. The basal metabolic rate (BMR) fell in all patients during the study.

Identification of an unusual gamma counter fault using Trigg's technique for trend detection.

A simultaneous deterioration in performance of several radioimmunoassays suggested that equipment was malfunctioning. Replicate counts from an automated gamma counter showed unacceptable variation during a 24-hour period; this variation was detected using Trigg's technique, a sensitive method for trend analysis, and was not identified by the usual laboratory testing procedures. A defective capacitor was found in the voltage stabilisation unit in the gamma counter, which probably made it responsive to small variations in the power supply to the laboratory.

One year's experience with a regional hormone assay service.

To provide a service in England and Wales for specialised assays, clinical chemists envisaged a multi-tier system with area, regional, and supraregional laboratories. The Department of Clinical Biochemistry at Addenbrooke's Hospital was established as a regional centre for hormone assays and formal operation started in June 1975. The assays which seemed most suitable for regional development in East Anglia were those for investigating the pituitary-gonad and pituitary-thyroid axes.

Interference in a radioimmunoassay for human thyrotropin.

Abnormally high plasma thyrotropin values were found by radioimmunoassay in some patients when an antiserum to porcine thyrotropin was used, normal results being obtained with an antiserum raised to human thyrotropin. These discrepancies were found in some subjects with no biochemical or clinical evidence of hypothyroidism and occasionally in sera from patients with unequivocal hyperthyroidism. We found a substance in serum that cross reacts with the anti-porcine antiserum, is stable on repeated freezing and thawing, and is independent of the 125I-labeled tracer preparation.

Observations on the automated calculation of radioimmunoassay results.

Radioimmunoassay standard curves derived by four different automated calculation methods are compared with those derived manually for five assays of clinical importance (thyroxine, triiodothyronine, thyrotrophin, alphafetoprotein, and human growth hormone). The three curve fitting methods (linear or cubic regression on log x versus logit y, cubic regression on log x versus y) produced considerable distortion of the manually derived curves, which in some cases could have impaired the accuracy of an estimate in a clinical sample and altered the clinical interpretation. Distortion patterns varied with the particular antigen assayed and with experimental conditions.

Semi-automated radioimmunoassays for total serum thyroxine and triiodothyronine.

Single stage semi-automated radioimmunoassays for total serum thyroxine (T4) and triiodothyronine (T3) are described which employ an automatic pipetting station, automatic gamma counter, and a programmable calculator with paper tape reader and printing facility. Both assays require only a small volume of unextracted serum, and are specific and sensitive. Their sample capacity, precision, speed, and cost are comparable with the measurement of serum protein-bound iodine.

A critical evaluation of separation methods in radiommunoassay for total triiodothyronine and thyroxine in unextracted human serum.

Methods for separating free and antibody-bound hormone in radioimmunoassays for total triiodothyronine (T-3) and thyroxine (T-4) in unextracted human serum are evaluated. For T-3 assay, a simplified second antibody technique has significant advantages over other methods and gives a mean interassay coefficient of variation of 7.2% over a wide range of values.