Pilot Experience with an External Quality Assurance Scheme for Acylcarnitines in Plasma/Serum.

The analysis of acylcarnitines (AC) in plasma/serum is established as a useful test for the biochemical diagnosis and the monitoring of treatment of organic acidurias and fatty acid oxidation defects. External quality assurance (EQA) for qualitative and quantitative AC is offered by ERNDIM and CDC in dried blood spots but not in plasma/serum samples. A pilot interlaboratory comparison between 14 European laboratories was performed over 3 years using serum/plasma samples from patients with an established diagnosis of an organic aciduria or fatty acid oxidation defect. Twenty-three different samples with a short clinical description were circulated. Participants were asked to specify the method used to analyze diagnostic AC, to give quantitative data for diagnostic AC with the corresponding reference values, possible diagnosis, and advice for further investigations.Although the reference and pathological concentrations of AC varied among laboratories, elevated marker AC for propionic acidemia, isovaleric acidemia, medium-chain acyl-CoA dehydrogenase, very long-chain acyl-CoA dehydrogenase, and multiple acyl-CoA dehydrogenase deficiencies were correctly identified by all participants allowing the diagnosis of these diseases. Conversely, the increased concentrations of dicarboxylic AC were not always identified, and therefore the correct diagnosis was not reach by some participants, as exemplified in cases of malonic aciduria and 3-hydroxy-3-methylglutaryl-CoA lyase deficiency. Misinterpretation occurred in those laboratories that used multiple-reaction monitoring acquisition mode, did not derivatize, or did not separate isomers. However, some of these laboratories suggested further analyses to clarify the diagnosis.This pilot experience highlights the importance of an EQA scheme for AC in plasma.

Factors associated with elevated or blunted PTH response in vitamin D insufficient adults.

OBJECTIVES: The purpose of this study was to examine factors associated with high or low parathyroid hormone (PTH) levels in relationship to vitamin D insufficiency. DESIGN: This was a cross-sectional study consisting of 516 healthy men and women, aged 30-85, all Caucasians with vitamin D insufficiency [serum 25(OH)D<45 nmol L(-1)]. The group was divided into quartiles by PTH levels and the highest and lowest quartiles were compared with regard to various factors likely to affect calcium metabolism. We used stepwise multivariable logistic regression to determine the independent association between PTH levels and other variables for men and women separately. RESULTS: We found that men in the lowest PTH quartile were significantly younger, had less energy intake, lower body mass index (BMI) and better kidney function compared with the highest PTH quartile. They had also higher ionized calcium, insulin-like growth factor (IGF1) and testosterone and were more likely to smoke. Women within the lowest PTH quartile were younger, had lower BMI and magnesium values and higher IGF1 levels and were more likely to smoke. Stepwise multivariate regression showed that IGF1, testosterone and BMI were significantly associated with PTH in men (R(2)=0.472) but smoking, BMI and kidney function in women (R(2)=0.362). CONCLUSIONS: Our results indicate that during vitamin D insufficiency, factors other than calcium and vitamin D may modify PTH response. These factors may be different between sexes and we have identified novel factors, IGF1 and testosterone in men which may be compensatory in nature and confirmed previous factors such as smoking, BMI and kidney function in women.

The Nordic Reference Interval Project 2000: recommended reference intervals for 25 common biochemical properties.

Each of 102 Nordic routine clinical biochemistry laboratories collected blood samples from at least 25 healthy reference individuals evenly distributed for gender and age, and analysed 25 of the most commonly requested serum/plasma components from each reference individual. A reference material (control) consisting of a fresh frozen liquid pool of serum with values traceable to reference methods (used as the project "calibrator" for non-enzymes to correct reference values) was analysed together with other serum pool controls in the same series as the project samples. Analytical data, method data and data describing the reference individuals were submitted to a central database for evaluation and calculation of reference intervals intended for common use in the Nordic countries. In parallel to the main project, measurements of commonly requested haematology properties on EDTA samples were also carried out, mainly by laboratories in Finland and Sweden. Aliquots from reference samples were submitted to storage in a central bio-bank for future establishment of reference intervals for other properties. The 25 components were, in alphabetical order: alanine transaminase, albumin, alkaline phosphatase, amylase, amylase pancreatic, aspartate transaminase, bilirubins, calcium, carbamide, cholesterol, creatine kinase, creatininium, gamma-glutamyltransferase, glucose, HDL-cholesterol, iron, iron binding capacity, lactate dehydrogenase, magnesium, phosphate, potassium, protein, sodium, triglyceride and urate.

Reference individuals, blood collection, treatment of samples and descriptive data from the questionnaire in the Nordic Reference Interval Project 2000.

The rules for recruitment of reference individuals, inclusion and preparation of individuals, blood collection, treatment of samples (and control materials) and analysis at the 102 medical laboratories attending the Nordic Reference Interval Project (NORIP) are given as well as the rules for central exclusion of reference individuals. The individuals (18-91-year-olds) should be evenly distributed on age and gender groups. The 3002 reference individuals who contributed at least one reference value to the finally suggested reference intervals were characterized using the information in the questionnaire. Gender, age and country are the main entries in the tables. Other variables in the cross-tables or figure are height, weight, body mass index, ethnic origin, heredity for diabetes, chronic disease, oestrogens or oral contraceptives, other medication, hard physical activity, previous blood donations, smoking habits, use of alcohol, hours since last meal and time of blood collection (hour, day of week, month, year). The Danes had the highest alcohol consumption and the Icelanders had the highest body mass index. The information in this article may interest potential users of the Nordic Reference Interval Project bio-bank and database (NOBIDA) in which serum, Li-heparin plasma and EDTA buffy coat from the mentioned individuals are stored below -80 degrees C.

A multicentre study of reference intervals for haemoglobin, basic blood cell counts and erythrocyte indices in the adult population of the Nordic countries.

Eight haematological quantities were measured in EDTA anticoagulated venous blood specimens collected from 1826 healthy male and female individuals between 18 and 90 years of age in the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden). The samples, collected between November 1999 and November 2001 as part of the Nordic Reference Interval Project (NORIP), were analysed on 12 different types of modern automated haematology instruments currently in use among the 60 laboratories participating in the study. Non-parametric reference intervals (between 2.5 and 97.5 percentiles) have been calculated for B-Haemoglobin (females 117-153 g/L, males 134-170 g/L), B-Erythrocytes (females 3.94-5.16 x 10(12)/L, males 4.25-5.71 x 10(12)/L), B-EVF (females 0.348-0.459, males 0.395-0.500), B-MCV (82-98 fL), Erc-MCH (27.1-33.3 pg), Erc-MCHC (317-357 g/L), B-Trc (females 165-387 x 10(9)/L, males 145 x 348 x 10(9)/L) and B-Lkc (3.5-8.8 x 10(9)/L). Partitioning of data according to age and gender was done according to a standardized procedure. For most variables the calculated reference intervals corresponded well with older and less well-defined reference intervals. The mean concentration of B-Haemoglobin increased by 0.08 g/L per year of age in women, and decreased by 0.1 g/L per year of age in men. B-Haemoglobin increased with body mass index in both men and women. Smoking increased the mean of B-Lkc by 1.1 x 10(9)/L and regular use of alcohol increased the mean of B-MCV by 0.8 fL. The influence of these factors was small overall and did not promote specific reference intervals.

Melanocortin receptor agonist transiently increases oxygen consumption in rats.

Acute injections of melanocortin (MC) agonist and antagonist are highly effective in reducing or increasing food take, respectively. Much less is known about how injection of MC receptor active substances affects metabolism, in particular during long term administration. Here we investigated the effect of 8 days continuous i.c.v. infusion of either MC receptor agonist MTII or the selective MC4 receptor antagonist HS024 on oxygen consumption, food intake and body weight in rats. We observed significant increase in oxygen consumption 2 days after the start of the MTII infusion. However, this increase had disappeared by day 4 of the study. No difference was observed in the oxygen consumption after injection of HS024. MTII substantially decreased the food intake during the first days, but then the feeding recovered and the body weight stabilised at a new level. The immediate effect of the MC receptor agonist on both food intake and metabolism was thus transient, even though the weight loss was maintained. The HS024 treated rats were hyperphagic throughout the test period, continuously gaining weight, resulting in increased fat pads and high leptin levels. This is the first study that describes long term effects of MC receptor agonist and antagonist on metabolism and energy balance.

Liquorice-induced rise in blood pressure: a linear dose-response relationship.

To clarify the dose-response and the time-response relationship between liquorice consumption and rise in blood pressure and explore the inter-individual variance this intervention study was designed and executed in research laboratories at University hospitals in Iceland and Sweden. Healthy, Caucasian volunteers who also served as a control for himself/herself consumed liquorice in various doses, 50-200 g/day, for 2-4 weeks, corresponding to a daily intake of 75-540 mg glycyrrhetinic acid, the active substance in liquorice. Blood pressure was measured before, during and after liquorice consumption. Systolic blood pressure increased by 3.1-14.4 mm Hg (P < 0.05 for all), demonstrating a dose-response but not a time-response relationship. The individual response to liquorice followed the normal distribution. Since liquorice raised the blood pressure with a linear dose-response relationship, even doses as low as 50 g of liquorice (75 mg glycyrrhetinic acid) consumed daily for 2 weeks can cause a significant rise in blood pressure. The finding of a maximal effect of liquorice after only 2 weeks has important implications for all doctors dealing with hypertension. There does not seem to be a special group of responders since the degree of individual response to liquorice consumption followed the normal distribution curve.

Increased bone mineral density in a population-based group of 70-year-old women on thiazide diuretics, independent of parathyroid hormone levels.

BACKGROUND: Several studies have shown greater bone mineral density (BMD) in people receiving thiazide diuretics compared with controls. Most researchers have related this association to the hypocalciuric effect of thiazides with subsequent rise in serum calcium and fall in parathyroid hormone (PTH) levels. Recent experimental evidence suggests, however, a direct effect of thiazides on osteoblast-like cells. OBJECTIVE: To test the hypothesis that the association of thiazides and raised BMD is independent of PTH levels in humans. SUBJECTS: A population-based group of 248 70-year-old Icelandic women, 51 receiving thiazide diuretics, 39 receiving other antihypertensive therapy and the rest acting as controls. MAIN OUTCOME MEASURES: The independent contribution of thiazide usage and PTH to BMD in a multivariate analysis. RESULTS: The mean BMD was 9.6% greater in the lumbar spine (P < 0.01) and 5.4% greater in the whole skeleton (P < 0.01) amongst thiazide users than in controls, reduced to 7.6% (P < 0.02) and 4.5% (P < 0.01), respectively, when corrected for fat mass which was 5.8 kg greater in the thiazide group. In a multivariate analysis, corrected for body weight and body composition, serum calcium and ln-PTH, thiazides remained a significant independent predictor of BMD in the total skeleton and lumbar spine, but not in the total hip or femoral neck. Thiazides explained about 3% of the variability in whole body and lumbar spine BMD. CONCLUSIONS: Thiazides augment or preserve BMD independent of PTH, implying other mechanisms.

The association between parathyroid hormone, vitamin D and bone mineral density in 70-year-old Icelandic women.

Parathyroid hormone (PTH) may be an important determinant of cortical bone remodeling in the elderly. Vitamin D status is one of the determining factors in this relationship. The aim of this study was to quantify the relationship between serum PTH, vitamin D and bone mineral density (BMD) in elderly women in Reykjavik (64 degrees N), where daily intake of cod liver oil is common and mean calcium intake is high. In PTH correlated inversely with 25(OH)D (r = -0.26, p<0.0 1). In multivariate analysis PTH correlated inversely with whole body BMD (mostly cortical bone) (R2 = 2.2%, p = 0.04) but not with the lumbar spine BMD, reflecting more cancellous bone. No association was found between 25(OH)D levels and BMD at any site in univariate or multivariate analysis. Osteocalcin, a measure of bone turnover, was negatively associated with BMD and this association remained significant when corrected for PTH levels. In summary, in this fairly vitamin D replete population with high calcium intake, PTH was negatively associated with total body BMD. We infer that suppression of PTH may reduce cortical bone loss, but other factors are likely to contribute to age-related bone remodeling and osteoporosis.

[Vitamin D intake and serum 25-OH-vitamin D concentration in different age groups of Icelandic women.].

OBJECTIVE: The aim of this study was to evaluate the vitamin D intake and serum concentrations of 25-OH-vitamin D (25-OH-D) in different age groups of Icelandic women. The seasonal variation of 25-OH-D and its relationship with parathyroid hormone (PTH) level was evaluated but some studies have indicated that subclinical vitamin D deficiency may lead to osteoporosis because of secondary elevations of parathyroid hormone levels and subsequent bone mineral release. MATERIAL AND METHODS: 25-OH-D was measured (RIA, Incstar) in serum from the following age groups of women; 12-15 years (n=325), 16, 18 and 20 years (n=247), 25 years (n=86), 34-48 years (n=107) and in 70 years old (n=308). PTH (IRMA, Nichols) was measured only in the 70 years old. vitamin D intake was assessed by a standardized food frequency questionnaire. The seasonal variation of 25-OH-D was evaluated in the age group 12-15 years and 70 years old. RESULTS: In the different age groups the 25-OH-D concentration was positively correlated to vitamin D intake (r=0.2-0.54; p<0.05). The mean concentration of 25-OH-D in 12-15 years old was 34.6+/-22 nmol/L compared to 53.9120 nmol/L in the 70 years old, p<0.01. The levels of the other age groups were in between. A marked seasonal variation in 25-OH-D was obser notved in the 12-15 years old with low vitamin D intake whereas only a slight seasonal variation was noted in the 70 years old with a mean vitamin D intake of 15 ug/day. CONCLUSIONS: The vitamin D status amongst 70 years old women in Iceland is good because of common intake of codliveroil and vitamin D supplements (83%). The desirable level for 25-OH-D in this age group seems to be around 50 nmol/L and this level is achieved by the intake of 15-20 ug/day (600-800 units) of vitamin D. Vitamin D deficiency is however common amongst 12-15 years old during late winter. Low serum 25-OH-D levels are also common amongst the other age groups studied during late winter. From the results it seems reasonable to recommend that foods like milk should be fortified with vitamin D in Iceland, especially during winter time.

Serum 25-hydroxyvitamin D levels and bone mineral density in 16-20 years-old girls: lack of association.

OBJECTIVE: Hypovitaminosis D has been shown to be associated with low bone mineral density in middle-aged and elderly women. The aim of this study was to evaluate whether such an association might exist in adolescent and young adult girls, approaching peak bone mass. DESIGN: Cross-sectional study carried out in late winter. SETTING: Reykjavik area at latitude 64 degrees N. SUBJECTS: Two-hundred and fifty-nine Icelandic Caucasian girls, aged 16, 18 and 20 years, randomly selected from the registry of Reykjavik. MAIN OUTCOME MEASURES: Bone mineral density in lumbar spine, hip, distal forearm and total skeleton was measured with dual-energy X-ray absorptiometry (DEXA) and compared with 25-hydroxyvitamin D levels [25 (OH)D] in serum, measured by radioimmunoassay. Calcium and vitamin-D intake were also assessed by a questionnaire. RESULTS: 18.5% of the girls were below 25 nmol L-1 in serum 25 (OH)D which has been recognized as the lower normal limit for adults. No significant association was found between 25 (OH)D levels and bone mineral density. CONCLUSIONS: Normal calcium and phosphate concentrations in plasma and normal bone mineral density are maintained in adolescent and young adult girls at lower 25 (OH)D levels than published 'normal' levels for middle-aged and elderly.

[Peak bone mass of Icelandic women and associated factors.].

OBJECTIVE: The aim of this study was to evaluate at which age peak bone mass is reached among Icelandic women. Previous studies on this subject have been conflicting indicating that this might be reached sometime between the age of 16 and 35 years. We have also analyzed associated nutritional and physical factors which might be of use for preventive measures against osteoporosis. MATERIAL AND METHODS: A random sample of 16, 18, 20 and 25 years old women in Reykjavik were invited, altogether 335 women participated. Bone mineral density (BMD) was analyzed by Dual Energy X-ray Absorptiometry (DEXA) in the lumbar spine, hip, forearm and total skeleton. Calcium, protein and vitamin D intake was assessed by a semiquantitative food frequency questionnaire. The level of 25-OH-vitamin D in serum was measured by a radioimmunoassay. Physical activity was assessed by a questionnaire. Multivariate analysis was performed by multiple linear regression. RESULTS: Maximal bone mineral density was reached for total skeleton, hip and forearm at the age of 20 years, BMD for the lumbar spine was 1% higher at the age of 25 than at 20 years but this was not statistically significant. No significant association was found between the calcium intake and BMD except in the subgroup of 18 years old women with calcium intake below 1000 mg/day. 25-OH-vitamin D levels were low (<25 nmol/L) in 15-18.5% of the groups but still no significant relationship was found with the bone mineral density. The strongest correlation was found between total BMD and the lean mass (0.38-0.53, p<0.01) but physical activity was also a significant factor in the age groups 16-20 years. About 25-30% of BMD variability can be attributed to these modifiable factors. CONCLUSION: Peak bone mass seems to be reached at the age of 20 and measures to increase it should therefore be emphasized before that age. Our results indicate that modifiable factors, especially lean mass and physical activity, are of considerable importance in the attainment of peak bone mass in women.

Is blood pressure commonly raised by moderate consumption of liquorice?

It is well known that excessive liquorice intake can induce sodium and fluid retention, hypokalaemia, hypertension and inhibition of the renin-angiotensin system. We tested whether regular moderate liquorice consumption (50 g and 100 g daily) raises blood pressure (BP) in a normotensive population. Ingestion of 100 g of liquorice daily (n = 30) caused a significant rise in systolic blood pressure (SBP) by a mean of 6.5 mm Hg (P < 0.001) and a fall in plasma potassium by 0.24 mmol/l (P < 0.001); the highest rise in SBP observed was 19 mm Hg. In a subgroup of 13 women the consumption of 50 g of liquorice daily also caused a significant rise in SBP of 5.6 mm Hg (P < 0.001) and DBP of 3.4 mm Hg (P = 0.002). A significant change in the cortisol/cortisone ratio in urine was observed during 100 g liquorice consumption indicating inhibition of 11 beta-hydroxysteroid dehydrogenase in kidneys. The results indicate that liquorice-induced hypertension might be more common than has been appreciated and it important for medical doctors to be on the alert for this effect in both the prevention and treatment of hypertension.

[Clinical chemistry and bacteriological testing in Iceland 1990.].

In this article we present the number and composition of clinical laboratory testing, both haematological, biochemical and bacteriological, performed at hospitals, primary care centers and private clinics in Iceland, in the year 1990. Inquiries were sent to 85 institutions, 52 (61%) responded. The number of assays performed at the laboratories/institutions not responding was estimated. The total number of assays performed in 1990 at these Icelandic institutions was 1.7 million which equals to 6.7 tests per person. Comparison to a similar investigation of assays done in 1982 showed that for those institutions which participated both years the number of tests other than bacteriological tests had increased by 23.2%. Tests done at larger hospitals had increased by 30%, at intermediate sized hospitals they had increased by 14.5%, and testing at primary care centers had decreased by 10% between 1982 and 1990. Bacteriological and clinical chemistry tests increased significantly or by 53% and 49% respectively. On the other hand hematological tests increased only by 1% and tests on urine decreased by 25%. By far the most common assay performed was blood count, ESR came second both years.

Creatine kinase isoenzyme BB in the cerebrospinal fluid of patients with acute neurological diseases.

In order to predict the outcome of patients with acute neurological symptoms at discharge, the concentration of creatine kinase isoenzyme BB (CK-BB) was determined by radioimmunoassay in the cerebrospinal fluid (CSF) of 115 consecutive patients. On admission and over the next 3 days the concentration of CK-BB was significantly increased in patients with brain death and other neurological sequelae compared with those with favourable outcome. There was a variation in time in concentrations of CK-BB between diseases causing neurological sequelae. Thus, cerebrovascular haemorrhages caused highest concentrations on admission, but cerebral ischaemia due to cardiac arrest caused highest concentrations 3 days after admission. On admission the CK-BB measurements were highly specific with high predictive value of positive result when distinguishing patients with brain death and other neurological sequelae from those without complications at discharge. However, when distinguishing patients with brain death from those with other neurological sequelae, the test was most specific and had highest predictive value of a positive result 3 days after admission.

Biochemical screening of airmen.

Starting in 1983, biochemical and hematological screening, including hemoglobin, hematocrit, mean cell volume, mean red cell hemoglobin concentration, white blood cell count, ESR, serum creatinine, cholesterol, triglycerides, ASAT (SGOT), ALAT (SGPT), G-GT and blood glucose, was performed in all Icelandic captains, copilots, flight engineers, and air traffic controllers. No hematological abnormalities were observed. One pilot had serum creatinine above 150 mmol.L-1; 48 airmen had serum cholesterol above 8.9 mmol.L-1; 15 had blood glucose above 7.9 mmol.L-1. The pilots had significantly lower serum triglycerides, ALAT, and ASAT than the captains. Fifty airmen had G-GT values above 50 IU.L-1. This group was urged to reconsider their alcohol habits and given medical and psychological advice as indicated. In this group the mean G-GT fell from 89 to 37 IU.L-1 during a period of approximately 2 years. No change in G-GT values was observed in those airmen who had a normal initial value. This study demonstrates the value of routine biochemical testing for airmen, particularly as regards blood glucose, serum cholesterol, and G-GT.

Familial elevation of serum thyroxine binding globulin in an Icelandic family.

A kindred of four generations with inherited elevation of serum thyroxine binding globulin (TBG) is reported. To our knowledge this is the twelfth kindred reported with this disorder. Of the 35 family members studied, 10 females and 5 males had elevated serum TBG. The patients were clinically euthyroid. The pedigree data was consistent with an X-chromosome linked mode of inheritance.