Measurement Of Serum Triglycerides Research Articles

Congenital adrenal hypoplasia, Duchenne muscular dystrophy, and glycerol kinase deficiency: importance of laboratory investigations in delineating a contiguous gene deletion syndrome

We describe an infant with adrenal insufficiency who was subsequently diagnosed with Duchenne muscular dystrophy (DMD) and hyperglycerolemia due to glycerol kinase deficiency. Karyotyping showed a deletion on the short arm of the X chromosome (p21.1 to p22.1). Molecular mapping revealed that the deletion extended from the 3' end of the DMD gene to a site telomeric to the loci for X-linked congenital adrenal hypoplasia and glycerol kinase deficiency. These results are diagnostic for an Xp21 contiguous gene deletion syndrome--so named because the deletion manifests as a distinctive cluster of otherwise unrelated single-gene disorders in the same individual. The Xp21 syndrome should be considered in any infant with adrenal insufficiency. Measurement of serum triglycerides (without glycerol blanking) and creatine kinase activity are simple screening tests that may facilitate early diagnosis and appropriate genetic counseling about risks of recurrence in subsequent offspring.

Laboratory facilities for investigating lipid disorders in the United Kingdom: results of the British Hyperlipidaemia Association survey.

To determine the availability of facilities for the investigation of hyperlipidaemia in the United Kingdom. A questionnaire was sent to all health districts in the United Kingdom. The response rate was 81%. All laboratories used enzymatic techniques to measure serum triglyceride and cholesterol concentrations, although there were differences in standardisation procedures. Reference ranges for serum lipids were quoted by 58% of laboratories while 50% quoted "desirable limits". Almost half specified that fasting blood samples were required. High density lipoprotein cholesterol concentrations were estimated by 75% and apolipoproteins AI and B by 14% of laboratories; there were differences in specimen type and considerable diversity in procedures used for measurement. Many laboratories were unaware of current recommendations for screening for hypercholesterolaemia in the community. The present survey indicated an urgent need for the introduction of better reference methods, standardisation, and quality assurance procedures before apolipoproteins become a routine part of coronary heart disease risk assessment.

Is the ratio of apo B/apo A-I an early predictor of coronary atherosclerosis?

It is unknown which lipoprotein in childhood is the best predictor of atherosclerosis later on in life. We measured serum triglycerides, total cholesterol, its subfractions (LDL, HDL, HDL 2, HDL 3) and apoproteins (A-I, A-II, B) in two groups of children. They were offspring of fathers who had severe coronary atherosclerosis or no coronary sclerosis, as determined by coronary angiography. Fasting blood lipids were measured in 49 children of fathers with severe sclerosis, and in 37 children of fathers without sclerosis. Sons of fathers with severe coronary atherosclerosis had higher levels of apo B and of the ratio apo B/apo A-I than sons of fathers free of atherosclerosis. No differences in lipid levels in daughters were observed. These observations suggest that apolipoproteins play a part in early atherogenesis. They further indicate that it may be possible to detect children who have a high probability of developing severe coronary atherosclerosis later in life.

Univariate and bivariate analyses of cholesterol and triglyceride levels in pedigrees.

A multivariate normal model for pedigree analysis is applied to fasting total serum cholesterol and total serum triglyceride measurements on 771 individuals in 95 pedigrees from Rochester, MN. Univariate and bivariate analyses are carried out to determine to what extent the aggregation and coaggregation in families of these two traits may be attributed to shared genetic and environmental factors. Pedigrees were ascertained through a sample of schoolchildren enriched for those with serum cholesterol levels in the highest and lowest deciles of their age- and sex-specific distributions. Ascertainment is corrected for by conditioning the likelihood on the trait values of the probands. Univariate results confirm the findings of previous studies indicating that familial aggregation of serum cholesterol and triglyceride levels is due both to shared genes and to shared environmental factors. Results of the bivariate analyses suggest that the coaggregation of cholesterol and triglyceride levels in these families is strongly influenced by both shared genes (pleiotropy) and shared environmental factors. These findings are consistent with our understanding of lipid metabolism and of specific environmental factors known to influence both traits.

Evidence for a regional component of body fatness in the association with serum lipids in men and women

Four hundred and seventy-two subjects (234 women and 238 men), 18 to 50 years of age, participated in percent body fat determination from underwater weighing, assessment of 6 subcutaneous skinfold thicknesses, and a 12-hour fast blood sampling for measurement of serum triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), total cholesterol (CHOL), and HDL-C CHOL ratio. Even though women were significantly fatter than men, they had lower TG, CHOL, and higher values of HDL-C CHOL ratio. Correlational and variance analyses showed that body fatness seemed to be more closely associated with serum lipids in men than in women. Moreover, the relationship between each skinfold and serum lipids indicated that subscapular and abdominal fat depots are more closely associated with serum lipids than other fat depots in men. In women, correlations were lower and regional differences attenuated. Furthermore, the regional trend observed in men remained significant after correction for concomitant variables such as age, cigarette smoking, habitual energy intake and energy expenditure, maximal aerobic power, and alcohol consumption. However, no effect of increasing body fatness was noted on HDL-C levels in women. Results of this study suggest that measurement of subscapular and abdominal fat should be considered when interpreting the blood lipid profile, particularly in males. A higher percentage of fat must be present in women than in men to observe alterations in serum lipids.

Enzymatic measurement of serum glycerol using a COBAS-BIO centrifugal analyzer

An enzymatic method for the measurement of glycerol using glycerol kinase coupled to pyruvate kinase and lactate dehydrogenase was adapted to a COBAS-BIO centrifugal analyzer. Routine standardization is not required under the optimized conditions since the calculation factor derived from the measurement of pure glycerol standard was found to be identical to the theoretical value. Excellent correlation between the method and the DuPont ACA triglyceride method was obtained. The coefficients of variation for within-run and day-to-day precision were less than 4%. Only 2 microL of serum is required, making this an excellent means for monitoring therapeutic glycerol administration in premature infants with hydrocephalus. The method has the sensitivity to measure glycerol concentrations as low as 0.1 mmol/L. This, together with the rapid analysis time (28 specimens in 10 min), makes it suitable for the correction of glycerol interference in the measurement of serum triglyceride.

Lipid profiles and lipase activities in children and adolescents with chronic renal failure treated conservatively or with hemodialysis or transplantation.

To elucidate the pathogenesis of hyperlipidemia in chronic renal disease in children and adolescents, we have measured serum triglyceride, total cholesterol, high density lipoprotein cholesterol (HDL-C) and activities of postheparin plasma lipoprotein lipase and hepatic triglyceride lipase (EC 3.1.1.3) in nine patients with transplants, and nine hemodialyzed and 18 conservatively treated patients with chronic renal failure. In 29 of 36 patients, serum insulin levels both in fasting and in response to oral glucose load were measured. The lipase activities were measured separately, utilizing antiserum against hepatic triglyceride lipase. All groups of patients had hypertriglyceridemia. The patients with endogenous creatinine clearance less than 20 ml/min/m2 had a low HDL-C level. The HDL-C level was correlated inversely with serum triglyceride level and positively with glomerular filtration rate. The lipoprotein lipase activities were low in patients with endogenous creatinine clearance less than 20 ml/min/m2. Although hepatic triglyceride lipase activities were not significantly low in any groups of patients, they were correlated with glomerular filtration rates in the conservatively treated patients with chronic renal failure. A defective triglyceride removal due to low lipase activities may contribute to uremic hypertriglyceridemia in these patients. On the other hand, patients with transplants had almost normal lipase activities and exhibited hyperinsulinemia; overproduction of triglyceride due to hyperinsulinemia may contribute to their hypertriglyceridemia.

A peroxidase-coupled method for the colorimetric determination of serum triglycerides.

We describe an enzymatic method for rapid, precise measurement of serum triglycerides with use of sample:reagent ratios as large as 1:200. Hydrolysis of triglycerides is catalyzed by lipase to produce glycerol and free fatty acids. The glycerol generated is then phosphorylated by adenosine 5'-triphosphate in the presence of glycerol kinase. Oxidation of the resulting glycerol 3-phosphate to produce hydrogen peroxide is catalyzed by L-alpha-glycerophosphate oxidase. An intense red chromogen is produced by the peroxidase-catalyzed coupling of 4-aminoantipyrene and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate with hydrogen peroxide. This sensitive chromogen system not only permits use of unusually small sample volumes, it also facilitates a linear response to serum triglyceride concentrations up to at least 10 g/L while displaying good Ringbom (measure of accuracy) characteristics.

Hyperalimentation Laboratory Support

The Committee on Nutrition, American Academy of Pediatrics has recently reported on the "Use of Intravenous Fat Emulsions in Pediatric Patients" (Pediatrics 68:738, 1981). The committee recommends restriction of the amount of fat emulsion given infants because of a lack of accurate and appropriate means of monitoring serum fatty acid and triglyceride concentrations. Such is not the case for triglycerides. The pediatric clinical chemistry laboratory has the ability to measure serum triglyceride concentrations to support hyperalimentation therapeutic monitoring.

Continuous-flow enzymic method evaluated for measurement of serum triglycerides with use of an improved lipase reagent.

We compared a modified enzymic continuous-flow method for serum triglycerides, in which a microbial lipase is used without protease, to an extraction-fluorometric method. Results (for total--blank) correlated well with those by the comparison procedure: enzymic = 1.002 fluorometric--14 mg/liter; r = 0.9968. Serum blanks were measured for each sample in both methods, and the concentration of free glycerol measured by the enzymic method was shown to be as much as 15 to 71% of the total triglyceride result in 7% of the samples analyzed. The dual-channel continuous-flow system provides automatic free-glycerol blank subtraction for the enzymic method.

Intravenous Fat-Tolerance Test in Ischaemic Heart Disease and Peripheral Vascular Disease

1. The intravenous fat-tolerance test and serum lipid and lipoprotein measurements were carried out in ninety-three normal subjects, fifty-one patients with ischaemic heart disease and thirty patients with peripheral vascular disease. 2. The fractional turnover rate of exogenous triglyceride was significantly slower in patients with ischaemic heart disease and in patients with peripheral vascular disease than in normal men. The rate was also slower in normal men than normal women. 3. Serum triglyceride and cholesterol concentrations were higher in both vascular disease groups than in control subjects. 4. The proportion of both groups of patients who had a subnormal fractional turnover rate of exogenous triglyceride was 35%, and 32% of patients had hypertriglyceridaemia in the fasting state; 27% of patients were hypercholesterolaemic. 5. Although the intravenous fat-tolerance test did not provide significantly better discrimination between cardiovascular patients and control subjects than did measurement of serum triglyceride, the results suggest that hypertriglyceridaemia in such patients may be separable into a group in which impaired triglyceride clearance may be partly responsible, and a group in which overproduction of serum triglyceride may be the major mechanism of the hyperlipidaemia.

Measurement of serum triglycerides by thin-layer chromatography and infrared spectrophotometry

A direct and nondestructive method for the quantitative determination of serum or plasma triglycerides has been developed. The lipid extract of 1 ml of serum is chromatographed on I-mm wet-thickness silicic acid layers prepared from a water–acetone slurry. Following elution, triglycerides are quantified by infrared spectrophotometry. For both synthetic and naturally occurring triglycerides, a nonlinear relationship of absorptivity as a function of concentration has been characterized. Triglyceride fatty acid chain length and degree of unsaturation have no significant effect on analytical results under the conditions described. Precision of the method is 2% and accuracy 4%. Recoveries average 96%. The method is sensitive to serum concentrations as low as 20 mg/100 ml. Triglyceride levels of a group of 51 healthy males, age 40 to 59, were determined. The mean postabsorptive triglyceride value was 93 mg/100 ml, with a standard deviation of 43 mg/100 ml. The system permits preservation of the triglyceride molecule intact for subsequent procedures such as characterization of the fatty acid moiety and substitution pattern.