Lack of value of serum gamma-glutamyl transferase in the diagnosis of hepatobiliary disease.

Serum gamma-glutamyl transferase (GGT, EC. 2.3.2.2. was measured in 173 patients with diseases of the hepatobiliary system (including metastatic cancer) and in 90 patients who were subsequently shown to have primary diseases of other etiology. All patients had been selected because they had abnormal alkaline phosphatase, aspartate aminotransferase or bilirubin on SMA 12/60 screening. Serum GGT was elevated in 97% of patients with primary hepatobiliary disease. The magnitude of the increase in GGT was variable in all groups and was unhelpful in differential diagnosis, even between medical and surgical cases. Moreover, GGT was abnormal in 69 patients who did not have primary hepatobiliary disease (77%), an incidence higher than that for other enzyme tests performed. We conclude that because GGT was more susceptible than other tests to spurious elevation in the absence of hepatobiliary disease and was unhelpful in differential diagnosis, it has little value apart from monitoring alcohol abuse and enzyme induction.     

A rapid, sensitive method for accurate analysis of individual bile acids in biological fluids by high performance thin-layer chromatography and densitometry

1. A rapid new micromethod for quantitative analysis of individual bile acids in duodenal juice by high performance thin-layer chromatography (HPTLC) and densitometry is described and evaluated by comparison with standard TLC and spectrophotometry. 2. Advantages of HPTLC over TLC include more rapid separation, better resolution and more sensitive detection (5 - 10 fold), without the need for prior extraction. Densitometry provides simple, direct and rapid quantitation. 3. The method is accurate and reliable over a range of bile acid concentrations. In the 0.5 mM range, recovery was greater than 89%, and coefficients of variation for within-day analysis were 2 - 12% and for between-day analysis were 6 - 18% for the individual bile acids. Twenty analyses can be performed by one worker in a single day. 4. We conclude that the method offers several advantages over most currently described techniques, is suitable for routine use and is deserving of wider application.     

A relative heat stability test for the identification of serum alkaline phosphatase isoenzymes

A new approach is presented for the identification of increased levels of serum alkaline phosphatase isoenzyme activity by heat inactivation. The pattern of enzyme stability at 56° over a 20-min period is compared with simultaneously determined patterns for control sera from patients with diagnosed liver and bone disease. This assessment of relative heat stability patterns has allowed the differentiation between liver and bone as the tissue source of increased serum alkaline phosphatase in 93% of the cases.     

A rapid double antibody non-equilibrium serum thyrotropin radioimmunnoassay suitable for primary neonatal hypothyroidism screening.

An improved double antibody radioimmunoassay for measuring human thyrotropin (h-TSH) in serum, suitable for neonatal primary hypothyroidism screening is described. The assay employs a non-equilibrium double antibody technique performed at an initial 37 degrees C followed by incubation at room temperature. Studies on the effects of various reaction parameters including time, temperature, antigen and antibody concentrations and the effect of various carrier proteins on the performance of standard curves were also performed. Using a 100-microliter serum sample for analysis, the assay sensitivity is routinely between 3 and 6 microU/mol of h-TSH (MRC 68/38) with interassay and intra-assay coefficient of variation values ranging from 6 to 14% over a wide range of control values. The incubation and phase separation is completed after 26 h with data available following automated counting and computation. Such a rapid assay facilitates a neonatal screening program for the early detection and treatment of primary neonatal hypothyroidism using either cord blood serum or early follow-up serum sampling in infants suspected on initial screening tests of an abnormality.     

Serum immunoglobulins in healthy children and adults. Levels of the five classes, expressed in international units per millilitre.

Serum levels of IgM, IgG, IgA, IgD, and IgE were determined in serum samples of 270 healthy Dutch children (aged 4-13 years) and of 30 healthy Dutch adults, the amounts being expressed in International Units per millilitre. Special attention is given to the IgD and IgE results, since the IgM, IgG, and IgA levels in mg per 100 ml of these sera and their implications have already been reported. In the children's sera the occurrence of relatively high IgD and IgE levels was frequently observed, whereas the adult group did not show excessive variation in this respect. The mean IgD levels found for adult males and females are 21 I.U./ml and 24 I.U./ml, respectively; the mean IgE levels for the same groups are 68 I.U./ml and 88 I.U./ml, respectively. The mean IgD and IgE levels in the children of each year group were usually higher than those of each of the juvenile groups and the mean level of the adult group was not statistically significant. A statistically significant influence of sex and season on the IgD and IgE levels could not be demonstrated in this material either. Three of the 270 children's sera showed an exceptionally low IgA content. In two of these cases the serum was sampled and studied a second time after an interval of four years, when the IgA deficiency proved to be still present. The IgE levels in the sera of these healthy IgA-deficient children were normal, whereas the presence of IgD could not be demonstrated.     

A new automated method for the determination of true creatinine in serum by means of the centrifichem centrifugal analyzer, based on Slot's principle; with special reference to low substrate concentrations.

A new automated method is proposed for the accurate determination of the true creatinine concentration in 20 microliter serum, based on the measurement of the initial rate of the decomposition reaction of the creatinine picrate complex caused by decreasing the pH. The results of this method, performed with a Centrifichem centrifugal analyzer system (type 300 F), are compared with the results obtained by two other methods: a manual method based upon the adsorption on Fuller's earth, and the Auto Analyzer method. In these comparative studies special attention is paid to the analysis of sera containing low (normal) substrate concentrations. Calculation of the orthogonal regression between the results obtained by the adsorption method (x) and the proposed method (y) gave: y=0.97x +/- 5 mumol/l (x=91.3 mumol/l, y-93.5 mumol/l), while for the correlation coefficient (r) 0.9721 was found. All sera (n=113) had creatinine concentrations between 40 and 180 mumol/l.     

The effect of long-distance running on some biochemical variables.

Biochemical variables have been measured in a group of volunteers during and after a long-distance run. Plasma glucose levels remained relatively constant and a significant decrease in plasma bicarbonate was noted. Plasma sodium, chloride, total protein, albumin and calcium showed significant increased of an order compatible with water losses occurring during the run. Plasma potassium, urea, creatinine, uric acid, phosphate and bilirubin all show much more marked and variable increases. The plasma enzymes alkaline phosphatase, lactate dehydrogenase, aspartate aminotransferase and creatine kinase likewise increased significantly throughout the run. Whilst most constituents showed a tendency to return to normal at 20-30 hours after the run, gross increases were observed for aspartate aminotransferase and creatine kinase.     

The biochemical consequences of cardiopulmonary bypass surgery in children.

The changes in serum enzyme activities after successful and uncomplicated cardiopulmonary bypass (CPB) surgery in children are described. After maximum serum enzyme activities were attained, they thereafter declined steadily without any secondary peaks of activity, to be at or near normal activities by the seventh day after surgery. The possible sources and mechanisms of enzyme leakage from tissues after CPB are discussed. The concentration of some physiologically important constituents were determined in pump prime fluids and in the common circulation on bypass. The consequences of haemodilution on small children were undesirably reduced concentrations of magnesium, calcium and albumin, and this state persisted for some days after the end of bypass. Some possible implications of such unphysiological pump primes are discussed. We suggest that ASp AT, Ala AT, CK-MB, magnesium, calcium and urea should be routinely monitored for the first four days after surgery.     

The determination of lipoprotein Lp(a) by rate and endpoint nephelometry

Rate nephelometry is a fast and convenient method for Lp(a) quantification. The linearity in the range of the physiological serum concentrations is good and there is good correlation with other immunochemical methods. The antibody consumption is some 50% higher when compared to the Laurell procedure if light scatter is measured in the RU mode. Measurements in the SU mode on the other hand consume less antibody than the Laurell procedure. The endpoint method, however, is more time-consuming and considered to be less accurate. In addition, only clear samples should be used. Lipemic sera should be cleared by lipase treatment or by high speed centrifugation. The treatment of samples with detergents causes a pronounced reduction of the immunochemical response and thus should be avoided.