Showing papers in "Annals of Clinical Biochemistry in 1987"
TL;DR: Biochemical abnormalities occurred in both forms of eating disorders; however, hypercholesterolaemia was more common in anorexia nervosa and abnormal liver enzymes were moreCommon in bulimia.
Abstract: We report the biochemical results in 90 women presenting to an eating disorders clinic: 61 who had bulimia, 22 with anorexia nervosa and seven unclassified. The results were compared with 30 control women. The group of women with an eating disorder had significantly higher concentrations of total CO2, calcium, AST, ALT, ALP, albumin and cholesterol and significantly lower concentrations of potassium, chloride and phosphate in the plasma. The elevated calcium could be accounted for in part by an increase in total CO2 and an increase in albumin. Hypokalaemia was strongly associated with self-induced vomiting and laxative abuse. Biochemical abnormalities occurred in both forms of eating disorders; however, hypercholesterolaemia was more common in anorexia nervosa and abnormal liver enzymes were more common in bulimia.
97 citations
TL;DR: Agreed requesting policies in various specialities and clinical circumstances, endorsed by senior clinicians and prestigious professional bodies, seems a promising approach to more appropriate test requesting; further objective studies of their long-term effects are needed.
Abstract: Studies of the effectiveness of various strategies for influencing clinicians' test-requesting behaviour are reviewed. Numerical rationing, although crude, effectively reduces unnecessary repeat testing without detriment to patient outcome. Educational programmes involving peer review show pronounced but short-lived effects. Simple feedback of information about numbers of tests requested and their costs is surprisingly ineffectual. Direct financial incentives, in a private health care system, also failed. Clinical budgeting, of benefit in experimental trials, has yet to be widely tested, and the savings on reducing laboratory requesting may not be large enough to be attractive to clinicians. Agreed requesting policies in various specialties and clinical circumstances, endorsed by senior clinicians and prestigious professional bodies, seems a promising approach to more appropriate test requesting; further objective studies of their long-term effects are needed. Redesign of request forms into a problem-orientated format may be the simplest and most effective contribution by the laboratory; this strategy deserves further critical appraisal.
89 citations
TL;DR: Data demonstrate the presence of progressive ‘hyperparathyroidism’ during pregnancy in Caucasian and Asian women and the higher PTH concentrations in Asian women may reflect the necessity of maintaining adequate plasma calcium concentrations through PTH-induced osteolysis in the face of vitamin D deficiency.
Abstract: Plasma calcium, serum 25 hydroxyvitamin D [25(OH)D], 1,25 dihydroxyvitamin D[1,25(OH)2D] and parathyroid hormone (PTH) have been measured in pregnant and newborn Caucasians and Asians. Calcium and 25(OH)D concentrations were lower in Caucasian than in Asian women at all four stages (three trimesters and during labour) of pregnancy. PTH concentrations were greater in Asian than in Caucasian women during the three trimesters, but not at labour, and increased in both groups through pregnancy, without a concomitant change in plasma calcium concentrations. There was a significant inverse correlation between calcium and PTH, as well as 25(OH)D and PTH, concentrations. These data demonstrate the presence of progressive 'hyperparathyroidism' during pregnancy in Caucasian and Asian women. The higher PTH concentrations in Asian women may reflect the necessity of maintaining adequate plasma calcium concentrations through PTH-induced osteolysis in the face of vitamin D deficiency. Relative hyperparathyroidism in Asians may contribute to net loss of calcium from the skeleton and osteopenia in Asian women. Calcium, 25(OH)D and 1,25(OH)2D concentrations were lower, and those of PTH higher, in Asian newborns compared with Caucasian newborns. Serum 1,25(OH)2D concentrations in the Asian newborn, though lower than respective maternal levels, were comparable with normal adult levels, indicating that 1,25(OH)2D biosynthesis is stimulated in the Asian newborn to compensate for the low serum 25(OH)D concentrations.
67 citations
TL;DR: This is the first report in the literature in which oestrogen and progesterone receptors in leiomyoma are significantly higher than in normal myometrium (P=0·0002).
Abstract: The content of cytoplasmic 17 beta oestradiol and progesterone receptors in human uterine leiomyoma and normal myometrium in the Negroid population was determined. Eighteen women of reproductive age, at various stages of the menstrual cycle, were included in the study. The serum oestrogen and progesterone concentrations were also measured. This is the first report in the literature in which oestrogen and progesterone receptors in leiomyoma are significantly higher than in normal myometrium (P = 0.0002). The steroid dependence of the growth of leiomyomas may be related to the steroid receptor level. The presence of persistently high concentrations of oestrogen and progesterone receptors in leiomyoma should be helpful in the treatment of this benign tumour.
67 citations
TL;DR: Accurate determination of the half-lives of the glucuronides was not possible due to the short sampling period, but M-6-G seemed to have a similar half-life to morphine, while M-3-G was eliminated more slowly.
Abstract: The analysis of morphine, morphine-3-glucuronide (M-3-G) morphine-6-glucuronide (M-6-G) by differential radioimmunoassay using iodinated label and three different antisera is described. These methods were used to measure concentrations of morphine and its conjugated metabolites in human plasma, over a 3-h period, following a single 10 mg intravenous dose. In 13 patients peak concentrations of M-3-G (739 nmol/L +/- 73.7 SEM) were approximately 10 times greater than those of M-6-G (71.3 nmol/L +/- 8.6 SEM). Times to reach these peaks were similar for both metabolites. Decay of morphine from plasma followed a biexponential pattern with a mean terminal half-life of 59.3 min (+/- 8.1 SEM, n = 11). Accurate determination of the half-lives of the glucuronides was not possible due to the short sampling period, but M-6-G seemed to have a similar half-life to morphine, while M-3-G was eliminated more slowly.
64 citations
TL;DR: A mechanism of bilirubin interference in kinetic Jaffé methods is proposed and the influence of picrate concentration, hydroxide concentration and temperature on the magnitude of bil IRU interference has been investigated.
Abstract: Negative interference by jaundiced plasma in kinetic Jaffe methods for plasma creatinine determination is caused by both conjugated and unconjugated bilirubin. The amount of interference observed is method- and temperature-dependent and is directly related to bilirubin concentration but is independent of the creatinine concentration. Bilirubin also significantly reduces the precision of the creatinine estimation. A mechanism of bilirubin interference in kinetic Jaffe methods is proposed and the influence of picrate concentration, hydroxide concentration and temperature on the magnitude of bilirubin interference has been investigated.
62 citations
TL;DR: The main conclusions and recommendations are as follows: Albumin measurement forms a limited, but useful part of the investigation of liver disease; a normal serum albumin concentration makes the diagnosis of cirrhosis unlikely, while a low level in viral hepatitis suggests either severe hepatocellular damage or other complications.
Abstract: This paper critically examines the usefulness of serum albumin measurement in the light of current laboratory practice and knowledge of the pathophysiology of albumin metabolism. The main conclusions and recommendations are as follows: (i) Albumin measurement forms a limited, but useful part of the investigation of liver disease; a normal serum albumin concentration makes the diagnosis of cirrhosis unlikely, while a low level in viral hepatitis suggests either severe hepatocellular damage or other complications. (ii) Albumin measurement is essential in selecting patients for, and in determining the amount and frequency of, albumin replacement. (iii) Serum albumin concentration provides a useful indication of prognosis in myeloma. (iv) In the long-term management of patients undergoing enteral or parenteral nutrition, serum albumin concentration is one of several parameters which, together, are useful in predicting the outcome of treatment. (v) The serum albumin concentration may provide a clue to the aetiology of unexplained oedema. (vi) Serum albumin measurement is useful in indicating the level of ionised calcium and of unbound unconjugated bilirubin.
58 citations
TL;DR: The results indicate that retinol-binding protein excretion may be increased in diabetic subjects without increased albumin excretion, and the possibility therefore exists that renal tubular damage may occur early in diabetic nephropathy without apparent glomerular dysfunction.
Abstract: A radioimmunoassay has been developed for the measurement in urine of retinol-binding protein (alpha 2-microglobulin) and used as an index of renal tubular function in adult Type 1 (insulin-dependent) diabetics and to define reference ranges in non-diabetic controls. There was a significantly greater excretion (P less than 0.001) of retinol-binding protein in the diabetic group compared to the controls in both overnight and daytime samples. There was a weak positive correlation with albumin excretion (r = 0.33; P less than 0.01) but no correlation with HbA1, duration of diabetes or arterial blood pressure. The results indicate that retinol-binding protein excretion may be increased in diabetic subjects without increased albumin excretion. The possibility therefore exists that renal tubular damage may occur early in diabetic nephropathy without apparent glomerular dysfunction.
56 citations
TL;DR: It is not justified to pursue negative findings using the more sensitive techniques of isoelectric focusing and imrnunofixation as any paraprotein or Bence Jones protein so revealed will be of doubtful significance.
Abstract: 2 It is essential to use good quality electrophoresis of serum and adequately concentrated urine to screen for paraproteins ,IOd Bence Jones protein. Their absence. using the techniques recommended. will exclude IJIJ'X. of cases of myeloma. It is not justified to pursue negative findings using the more sensitive techniques of isoelectric focusing and imrnunofixation as any paraprotein or Bence Jones protein so revealed will be of doubtful significance.
54 citations
TL;DR: Adaptation of coenzyme stimulation assays for the nutritional assessment of thiamine, riboflavin and pyridoxine on the Cobas Bio centrifugal analyser offers improved precision over existing procedures and takes advantage of the high throughput capabilities of the instrumentation.
Abstract: Adaptation of coenzyme stimulation assays for the nutritional assessment of thiamine, riboflavin and pyridoxine on the Cobas Bio centrifugal analyser are described. Whole blood was collected into a...
42 citations
TL;DR: The measurement of serum follicle stimulating hormone (FSH) and luteinising hormone (LH), together with the appropriate sex steroid, is of great value in the investigation of delayed and precocious puberty, hypogonadism, subfertility, polycystic ovarian disease and hypothalamic-pituitary disorders.
Abstract: The measurement of serum follicle stimulating hormone (FSH) and luteinising hormone (LH), together with the appropriate sex steroid, is of great value in the investigation of delayed and precocious puberty, hypogonadism, subfertility, polycystic ovarian disease and hypothalamic-pituitary disorders. Dynamic function testing of the hypothalamic-pituitary-gonadal axis should be restricted to a few defined situations. Sequential LH measurements, either in serum or in urine, may be used to time ovulation during artificial insemination or in vitro fertilisation programmes. No special precautions are necessary when sampling for FSH and LH measurement; serum is preferred to plasma and should be stored frozen before assay. Aliquots of timed urine specimens of known volume should be stored frozen without preservative. Gonadotrophin results should be available within 2-3 weeks; laboratories unable to meet this schedule are advised to send their samples to a Regional Centre for assay. Reagents for the radioimmunoassay of FSH and LH are readily available, and standard techniques have been developed for their use. Laboratories using 'in-house' methods should pay particular attention to the matrix used for preparing standard solutions, the purification of radioligands and the optimisation of the separation system. Low cost matched reagents of proven performance are available in kit form from the Chelsea Hospital for Women; several commercial kits are also available, although few are widely used in the UK. The overall performance of laboratories in the UK External Quality Assessment Scheme (EQAS) for FSH and LH has remained steady for several years. Of the 130 participants, only about 15% in each scheme have 'good' performance (cumulative bias less than 10%, plus cumulative variability of bias less than 10%), whilst a similar proportion have 'unacceptable' performance (cumulative bias greater than 20% and/or cumulative variability of bias greater than 25%). The remaining 70% of laboratories have 'adequate' performance but are at risk of producing results that are clinically misleading. Within any one method group, the performance of FSH and LH assays are closely related. Optimal assay performance depends upon sensible laboratory management to ensure skilled operators, a regular programme of reagent/kit renewal, comprehensive internal and external quality assessment, and attention to detail in all aspects of gonadotrophin assay. The working range of each individual assay should be defined and no absolute result reported from outside this range.(ABSTRACT TRUNCATED AT 400 WORDS)
TL;DR: Serotonin levels determined by the three different methodologies showed a high correlation but differed significantly: caution should be exercised when comparing blood serotonin results where different methods are employed.
Abstract: Recent interest in conditions associated with increased blood serotonin level has highlighted the need for consistency between assay methods to allow for more accurate delineation of serotonin variables. To this end, comparison was made between a spectrofluorimetric technique frequently used in the past and two potentially more specific high performance liquid chromatographic procedures. Normal ranges and diurnal variations for blood serotonin in adults, normal, autistic children and children with developmental dysphasia were also determined. No significant difference was found between serotonin level in blood drawn by simultaneous venepuncture and capillary (fingerprick) collection. Whilst there was no evidence of circadian rhythm, seasonal variation with mean blood serotonin levels significantly lower in summer than in two successive winters was suggested. Blood serotonin values in normal children tended to decline with increasing age. No similar maturational effect was apparent in autistic children. The mean level for autistic children in winter was significantly higher than that for normal children in the same season; despite this there was considerable overlap of blood serotonin levels between normal and autistic groups. Serotonin levels determined by the three different methodologies showed a high correlation but differed significantly: caution should be exercised when comparing blood serotonin results where different methods are employed.
TL;DR: It seems likely that supplies of GH for therapeutic use, previously scarce, will become abundant in the near future, and results of a successful clinical trial in 36 children with GH deficiency have been reported.
Abstract: In 1958, Raben extracted growth hormone (GH) from human pituitary glands at post mortem, I and used intramuscular injections for a period of 10 months to produce an increased growth rate in a 17-year-old male with hypopituitarism.? By 1976, 642 children with growth hormone deficiency had been treated with human pituitary GH in the UK;~ and in early 1985 around 900 children in the UK were receiving GH therapy.\" During that year, there were reports of four deaths from the rare encephalopathy, Creutzfeldt-Jakob disease, in young adults who had been treated with GH.57 Although it seems that pituitary glands extracted by current methods do not contain the virus responsible for Creutzfeldt-Jakob disease,\" treatment with human pituitary GH has been stopped in most countries. However, in the early I98(ls, it became possible to synthesise the biologically-active methionyl analogue of human GH by recombinant DNA technology:' and results of a successful clinical trial in 36 children with GH deficiency have been reported. HI Thus, it seems likely that supplies of GH for therapeutic use, previously scarce, will become abundant in the near future. The time is ripe for a reappraisal of who is likely to benefit from GH therapy.
TL;DR: P pH adjustment versus no pH adjustment and removal of particulate material versus retention were compared in a cross-over design and none of the pH-adjusted samples showed discrepancies between the vortex mix treatment and supernatant results for any of the analyses.
Abstract: The observation that albumin may be precipitated in deep frozen urine samples I prompted further investigation of whether the phenomenon occurred with other urinary proteins. Since pH adjustment of urine specimens prior to deep freezing is accepted practice for specimens for the By-microglobulin (82m) assay, pH was also investigated. Urine specimens were collected from 10 healthy subjects and showed pH values ranging from 4·9 to 6·9. Each specimen was assayed for 8 2m 2 and albumin:' within I h of voiding. The remaining urine was in each case divided into two portions, one of which was adjusted to pH 7·(J using I M NaOH. Aliquots from both portions were stored at -20°C. Repeat 8 2m and albumin analyses were performed after 3 weeks' and 6 weeks' storage. All determinations were performed in duplicate and all samples were assayed within the same batch on each occasion. Two methods of preparing the samples for assay were used: (a) the sample was centrifuged for 10 min at 1000 g and supernatant taken for assay; and (b) the sample was vortex mixed immediately prior to assay so that particulate matter was included. pH adjustment versus no pH adjustment and removal of particulate material versus retention were therefore compared in a cross-over design for each of the 10 specimens. After 6 weeks' storage the samples were also assayed for gamma-globulin using a newly developed ELISA (a modification of the albumin method). None of the pH-adjusted samples showed discrepancies between the vortex mix treatment and supernatant results for any of the analyses.
TL;DR: The results suggest that fructosamine is slightly more sensitive in detecting borderline-abnormal glucose tolerance, whereas no differences are observed for detection of clearly abnormal oral glucose tolerance tests.
Abstract: Glycosylated haemoglobin and glycosylated serum protein concentrations (fructosamine) have been monitored in patients suspected of diabetes mellitus (n = 183), in pregnant women suspected of gestational diabetes (n = 250) and in control groups (n = 184). The response to the standard 75 g oral glucose tolerance test was used to confirm or reject the diagnosis, using different criteria for detection of diabetes mellitus compared to detection of gestational diabetes. A slightly higher sensitivity was observed for fructosamine compared to glycosylated haemoglobin to detect impaired glucose tolerance (52 vs 44%) or gestational diabetes (17% vs 8%). For detection of diabetic oral glucose tolerance no difference was observed between glycosylated haemoglobin and fructosamine; sensitivity for both parameters was 67%. The results suggest that fructosamine is slightly more sensitive in detecting borderline-abnormal glucose tolerance, whereas no differences are observed for detection of clearly abnormal oral glucose ...
TL;DR: Atomic absorption measurements of ground state atoms being measured by emission of radiation would approximate to those of the total number of atoms present and should therefore be easier, more accurate and more precise than emission measurements of the few excited atoms.
Abstract: being measured by emission of radiation would be present. Atomic absorption measurements of these ground state atoms would approximate to those of the total number of atoms present and should therefore be easier, more accurate and more precise than emission measurements of the few excited atoms. The implications for clinical analyses may be deduced from Fig. 1 which shows the calculated ratios of excited to unexcited atoms for some clinically important elements at temperatures obtained with atom sources available in laboratories. The calculations were made by using the Boltzmann equation (1) which assumes thermal equilibrium and does not consider excitation by suprathermal chemiluminescence, ionisation or any other interactions that affect the ratios Nj/No, so that the data in Fig. 1 are for general comparisons and are not absolute.
TL;DR: The glutaraldehyde method was found to be much more effective than the periodate method for conjugating alkaline phosphatase to the antibodies and it was possible to detect human and mouse IgG at concentrations as low as I ng/mL.
Abstract: The periodate method was found to be most effective for preparing horseradish peroxidase-sheep anti-human and horseradish peroxidase-donkey anti-mouse immunoglobulin (IgG) conjugates. The conjugate...
TL;DR: Measurement of these two compounds in plasma gives a useful clinical index of the severity of poisoning and an indication of prognosis and the need for additional therapy.
Abstract: Salicylate and paracetamol are widely used and effective analgesic drugs which are available in the UK and much of the world without prescription. Both drugs are highly toxic when taken in overdose and the amounts which produce toxicity may be only twice the daily dose taken for chronic pain. Persons with impaired hepatic metabolism or renal insufficiency may be particularly at risk of developing severe toxicity due to their inability to metabolise and excrete the drugs efficiently. Measurement of these two compounds in plasma gives a useful clinical index of the severity of poisoning. an indication of prognosis and the need for additional therapy. For salicylate the nomogram published by Done', and shown modified here in molar uits (Fig. I), alIows an estimate of the peak salicylate level to be made. It relies on the fact that salicylate is excreted with zero order kinetics. For paracetamol, prognosis requires the use of a prediction graph (Fig. 2) which indicates the need for active treatment with a specific thiol antidote, N-acetylcysteine (NAC).2 The requirement for these prediction graphs is due to a further similarity between these two drugs, namely the fact that in the early stages following ingestion of even a large quantity of tablets, the patient may exhibit no physical signs and experience minimal discomfort. Firm diagnosis at this stage relies almost entirely upon measurement of the plasma drug concentration, and treatment may have to be
TL;DR: The data indicate that serum fructosamine levels do not accurately reflect those of glycated albumin, as has recently been suggested, in type I insulin-dependent diabetics where glycaemic control fluctuates more than in type IIDiabetics.
Abstract: We have measured serum glycated albumin (GSA) by affinity chromatography and immunoturbidimetry, and serum fructosamine using a Cobas FARA analyser in blood samples from 37 type I diabetics and 21 ...
TL;DR: It is argued that with increasing lean body mass the increased production of creatinine is counterbalanced by increasing volume of distribution, i.e. body fluid compartment.
Abstract: In the excellent recent review article (Ann Clin Biochem 1986; 23: 243-50) on creatinine clearance, Dr Payne discusses the usefulness of plasma creatinine to detect abnormal or changing glomerular function and asks 'can the clinical usefulness of plasma creatinine in each sex be increased by taking account of body size?'. We have recently completed a study on the relationship between body size and plasma creatinine concentration.' In this study, 285 men and 385 women were included and lean body mass was calculated from skinfold thickness. We could not find a significant correlation between plasma creatinine and body weight, lean body mass, or body mass index, and we have argued that with increasing lean body mass the increased production of creatinine is counterbalanced by increasing volume of distribution, i.e. body fluid compartment. Therefore, we suggest that in order to narrow the reference range, other factors such as diet, exercise etc. may have to be studied in detail.
TL;DR: A simple plasma emission spectroscopic method for the determination of iron in liver and cardiac tissue is described and data on patients with haemochromatosis and transfusion siderosis are presented.
Abstract: A simple plasma emission spectroscopic method for the determination of iron in liver and cardiac tissue is described. Using this technique, iron was extracted quantitatively from liver tissue of mass 14.2 to 65.4 mg wet weight, and heart tissue of mass 5.9 to 27.4 mg wet weight. Iron added to liver as aqueous ferric nitrate was recovered in the range 93 to 108%. Reference ranges for liver and myocardial iron on post mortem tissue gave respectively mean values of 0.841 mg/g dry weight (Range 0.310 to 1.600, n = 37) and 0.340 mg/g dry weight (Range 0.290 to 0.470, n = 8). Data on patients with haemochromatosis and transfusion siderosis are also presented.
TL;DR: Significant alterations in the relative concentrations of oleic and arachidonic acids were found after storage at +4°C for 24 h, which has important implications in the study of changes in erythrocyte fatty acids in cancer and diabetes.
Abstract: A capillary gas liquid chromatography method was established for the routine determination of fatty acid profiles from washed erythrocyte membranes. Only the five major fatty acids found in erythrocytes (palmitic, stearic, oleic, linoleic and arachidonic acids) had acceptable precision (CVs less than 10.0%) for use in establishing quantitative differences between groups of individuals. Reference values were established for the relative amounts of these five fatty acids in adults. Significant alterations in the relative concentrations of oleic and arachidonic acids were found after storage at +4 degrees C for 24 h, which has important implications in the study of changes in erythrocyte fatty acids in cancer and diabetes.
TL;DR: A simple automated 'in house' immunoturbidimetric (IT) assay for albumin in urine using a Cobas Bio centrifugal analyser (Roche Diagnostics, Welwyn Garden City, Herts, UK) is described.
Abstract: Sensitive assays for urine albumin are being used for the measurement of levels of protein which are above normal but below the limit of detection of commonly used tests for proteinuria. Laboratories are being increasingly required to measure these low concentrations of albumin in urine since this slight albuminuria may be associated with the development of diabetic nephropathy.' We describe a simple automated 'in house' immunoturbidimetric (IT) assay for albumin in urine using a Cobas Bio centrifugal analyser (Roche Diagnostics, Welwyn Garden City, Herts, UK). Sathianathan, Rege and Barron/ have described a similar procedure. Our analysis, however, is preceded by a colorimetric protein assay on the Cobas Bio to screen for proteinuria in excess of 21K) mg/L which may cause antigen excess in the albumin assay. We have also assessed the IT assay by comparison with a commercially available radioimmunoassay (RIA) (Albumin, Diagnostic Products Corporation, Los Angeles, CA IJIK145, USA).
TL;DR: Purple pigment extracted from the urinary catheters and collecting bags of two elderly female patients was analysed by a variety of chemical techniques, including mass spectroscopy and nuclear magnetic resonance, and indicates that the molecular structure of the pigment is either a steroidal or bile acid conjugate.
Abstract: Purple pigment extracted from the urinary catheters and collecting bags of two elderly female patients was analysed by a variety of chemical techniques, including mass spectroscopy and nuclear magnetic resonance. Although previous studies identified the pigment as indigo, we failed to confirm this. Our analysis also demonstrated that indicanuria is not a requirement for the production of the pigment and furthermore indicates that the molecular structure of the pigment is either a steroidal or bile acid conjugate.
TL;DR: Urine total protein determination by a trichloroacetic acid precipitation method was automated on a Cobas Bio centrifugal analyser, thus saving time and providing a faster turnround time.
Abstract: Urine total protein determination by a trichloroacetic acid (TCA) precipitation method was automated on a Cobas Bio centrifugal analyser. The assay measures the turbidity at 420 nm when a 50 microL sample is mixed with 150 microL of 30 g/L TCA at 25 degrees C. Samples up to 5 g/L can be measured by this method and interference due to pigments and turbidity can be minimised by running a blank with 1.25% hydrochloric acid (HC1) instead of TCA. The standard curve is stable and can be stored in the microcomputer and used again. Within-assay precision (CV) varied from 2 to 4.6% and between-assay precision varied from 1.8 to 5.4%. Analytical recovery ranged from 95 to 106.5% and the results correlated well with those obtained by a manual TCA method (r = 0.98). The method is easy to perform and is considerably faster than the manual procedure, thus saving time and providing a faster turnaround time.
TL;DR: The value of c osmolality measurements in clinical practice is extremely restricted and an osmometer is a useful instrument for a laboratory to possess.
Abstract: The term 'osmolality' is used to denote the total number of particles in a solution. It is determined by the degree of dissociation or association of the molecules present per given mass of solvent and its units are millimoles per kilogram of solvent. The term 'osmolarity' refers to the concentrations of solute particles per volume of solution and its units are millimoles per litre. When a solution is separated from its solvent by a semi-permeable membrane, solvent will pass into the solution. The hydrostatic pressure which must be applied to the solution to prevent this is the osmotic pressure and, for a truly semi-permeable membrane, it is determined by the osmolality of the solution. In the case of cell membranes, which allow passage of some solutes, the osmotic pressure is dependent on the concentration of the particles which do not pass through the membrane; this has been termed the 'effective' osmolality or tonicity. I Osmolality measurements on biological fluids are made in many clinical chemistry laboratories and also outside the laboratory in some intensive care wards and other specialist clinical units. Although an osmometer is a useful instrument for a laboratory to possess, the following discussion will show that the value of c osmolality measurements in clinical practice is extremely restricted.
TL;DR: The proposed spectrophotometric method minimises the effect of turbidity and permits the measurement of concentrations below 0–3 μmol/L.
Abstract: A spectrophotometric method for the simultaneous calculation of the concentrations of oxyhaemoglobin, methaemoglobin and bilirubin in cerebrospinal fluid is described, based on the first and second derivative spectrum between 350 and 650 nm. Specificity compares favourably with other methods currently in use. The proposed method minimises the effect of turbidity and permits the measurement of concentrations below 0.3 mumol/L.
TL;DR: It is recommended that two-point calibration of the assay be performed using a low calcium standard rather than setting on the baseline, resulting in flattening of the calibration curve.
Abstract: The reasons for the non-linearity of the standard curve for the calcium-cresolphthalein complexone reaction have been investigated. Calcium forms both 1:1 and 2:1 complexes with cresolphthalein complexone; at low calcium concentrations the 1:1 complex predominates and causes non-linearity. At high calcium concentrations the cresolphthalein complexone concentration becomes limiting, resulting in flattening of the calibration curve. It is recommended that two-point calibration of the assay be performed using a low calcium standard rather than setting on the baseline.
TL;DR: Ethylene glycol in plasma, urine or dialysis fluid is analysed as the phenylboronate derivative by mixing with acetonitrile/acidified 2,2-dimethoxy-propane containing Phenylboronic acid and gas-liquid chromatography using propane-1,3-diol as a reactive internal standard.
Abstract: Ethylene glycol in plasma, urine or dialysis fluid is analysed as the phenylboronate derivative by mixing with acetonitrile/acidified 2,2-dimethoxypropane containing phenylboronic acid. After centrifugation, a portion of the supernatant is analysed directly by gas-liquid chromatography using a 3% OV-101 column at 150 degrees C and flame-ionisation detection. Propane-1,3-diol is used as a reactive internal standard. The limit of accurate measurement is at least 0.1 g/L and the linear range extends up to 5.0 g/L. No sources of interference have been identified.