Quality specifications for glycated hemoglobin A1c.

Berne has suggested that a change in the measured value (in per cent) of GHbA1c that is smaller than 1.0% does not lead to any therapeutic action from the clinician. Since the meeting of the "Friibergh Herrgård Seminar", April 23-24, 1990 on the "Medical Need for Quality Specifications in Laboratory Medicine" we have discussed this with our specialists at the Kuopio University Hospital and they share Berne's opinion. Keeping this in mind we have standardized our method so that the total analytical variation of the GHbA1c is small as compared to the measured biological variation of GHbA1c in nondiabetic and diabetic subjects. In this report we describe how we have succeeded in keeping the coefficient of variation of our routine method for GHbA1c analyses small enough for clinical purposes.

Correlation between the ratio of serum low-density lipoprotein cholesterol and high-density lipoprotein cholesterol with that of serum apolipoproteins B and A-I.

Phosphowolframate/magnesium chloride, a commonly used precipitation method for the determination of high-density lipoprotein cholesterol in human serum, yields a supernatant containing almost all of the lipoproteins apo A-I and apo A-II but no lipoprotein apo B. The correlation between high-density lipoprotein cholesterol and apo A-I was very high (r = 0.94), as well as that between the precipitation method and ultracentrifugal analysis (r > 0.95, P < 0.001). In contrast, detergent precipitation (for the determination of low-density lipoprotein cholesterol in human serum) produced sediments which contained the major proportion of apo B and only minor amounts of apo A-I and apo A-II. The precipitation method for low-density lipoprotein cholesterol showed very good agreement with ultracentrifugal analysis (r = 0.99). Yields of 80.2% were obtained for apo B with both methods. Results obtained using the precipitation methods showed excellent agreement with those obtained using the Friedewald formula (r > 0.99). Results were also very similar when hypertriglyceridemic serum samples were briefly centrifuged before analysis of cholesterol, high-density lipoprotein cholesterol and triglyceride values. The present study shows highly significant correlations between cholesterol/high-density lipoprotein cholesterol or low-density lipoprotein cholesterol/high-density lipoprotein cholesterol and apo B/apo A-I ratios (P < 0.001). Apo B and apo A-I levels could be used in addition to low- and high-density lipoprotein cholesterol values when assessing the risk of cardiovascular disease, if the methods for determining serum apolipoproteins have been properly standardized.

Contents of apolipoprotein A-I, A-II and B of the human serum fractions for high-density and low-density lipoproteins prepared by common precipitation methods.

Two common precipitation methods for the determination of HDL-cholesterol in human serum were used, dextran sulphate/MgCl2 and phosphowolframate/MgCl2. They yield supernatants which contained almost all of the apoA-I and apoA-II lipoproteins but no lipoprotein apoB. The correlations between chol-HDL and apoA-I were about the same with these methods (r = 0.79 and 0.80). The correlation between the precipitation methods and ultracentrifugal analysis for chol-HDL was highly significant (r = > 0.95). Correspondingly, two common precipitation methods for the determination of LDL-cholesterol in human serum, buffered heparin, and polyvinyl sulphate procedures, produced sediments, which contained the major proportion of the apoB and only small amounts of apoA-I and apoA-II. However, yields of only 69.0-80.2% were obtained for apoB from the sediments and of 85.8-89.4% from supernatants calculated as the difference from chylomicron free serum. This difference might be due to alterations of the molecular structure of apoB by the precipitation reagents. Comparison of the results with the precipitation methods to those using the Friedewald formula showed excellent agreements (r = > 0.91). Very comparable results were also obtained in the case of marked hypertriglyceridaemia provided that the serum samples were briefly centrifuged before analysis of chol, chol-HDL, and triglyceride values for the formula of chol-LDL. The precipitation methods for chol-LDL showed very good agreement with the values obtained by ultracentrifugal analysis (r = > 0.93). There were no remarkable differences in the correlation of apoB and chol-LDL values measured by different methods (r = 0.85). According to the present results it was found that highly significant correlations existed between chol/chol-HDL or chol-LDL/chol-HDL and apoB/apoA-I ratios (p < 0.001). It is quite evident that apoB and apoA-I values could be used to replace chol-LDL and chol-HDL values when the risk for the cardiovascular diseases is to be assessed.

Basic urinalysis and urine culture: Finnish recommendations from the working group on clean midstream specimens.

A recommendation for basic urinalysis and urine culture is published as an attempt to improve the clinical value of urinary tests and to create a system that utilizes laboratory work as sensibly as possible. More clinical background information is needed when basic urinalysis and urine culture is performed in stages. Collection and storage of urine specimens are standardized in addition to used equipment and bacterial culture. Cytological supravital stain improves qualitative and quantitative findings of urine sediment cytology. A close cooperation between central hospital district is necessary and stressed for further bacterial cultures in more complicated microbiological findings.

Finnish recommendation for methods used in urinalysis: results for five-year period.

A recommendation concerning basic urine examinations and bacteriological cultures was published in 1983 in Finland including three clinical indication groups with different screening strategies. Close cooperation between laboratory experts and clinicians as well as much training in urine sediment cytology were essential before the new principle became widely accepted. Decreased workload in laboratories in clinically less significant cases was shown with the use of the full capacity and qualities of complete urinalysis when needed. Standardized test procedures combined with sediment staining improved the clinical efficiency of urine microscopy.

L-Tryptophan administration in man: effects on gonadotrophin, growth hormone and cortisol secretion and on sexual motivation.

Long-lasting administration of L-tryptophan in neurologic patients caused a slight reduction of plasma luteinizing hormone levels without modifications of sexual motivation. Plasma follicle stimulating hormone concentrations were not altered by L-tryptophan. Short-lasting loading of L-tryptophan caused a statistically significant increase of plasma growth hormone levels, and a fall of plasma cortisol values in neurologic patients without neuroendocrine disorders. The pattern of plasma cortisol response to L-tryptophan loading was different in patients with neuroendocrine disorders. Plasma gonadotrophins seemed to be slightly reduced after the L-tryptophan loading.