Scandinavian Journal of Clinical & Laboratory Investigation最新文献

The concentration of chromogranin A in serum (s-CgA) is a general marker of neuroendocrine neoplasms. Unfortunately, s-CgA is increased in several other clinical conditions, including renal failure. The physician who assesses s-CgA values must consider the patients' renal function. How this should be done is not clear. We developed an adjustment formula from the association between median s-CgA and the estimated glomerular filtration rate (eGFR) in 2708 patients where s-CgA was measured by the CgA II KRYPTOR method. We used multivariable fractional polynomial quantile regression with the model ln(s-CgA) = c₀ + c₁ × sex + c₂ × age + c₃ × eGFR, thus accounting for sex and age. The final adjustment formula could be simplified to s-CgA₁₀₀ = (eGFR / 100) × s-CgA, where s-CgA₁₀₀ is an indication of what s-CgA would be if eGFR in the same patient was 100 mL/minute/1.73 m². In patients with eGFR > 100 mL/minute/1.73 m² no adjustment was done. We tested the formula on another patient population (n = 1563), where s-CgA was measured by a RIA method. S-CgA₁₀₀ proved to be independent of eGFR in that population. The clinical validity of s-CgA₁₀₀ must await further investigations.

Vitamin B12 (s-cobalamin) and methylmalonic acid (s-MMA) are often interpreted together to diagnose cobalamin deficiency, in context with patient symptomatology, which is many cases is unspecific. Today, clinicians assess test results in relation to the univariate reference limits or decision limits. As s-MMA depends on renal function (glomerular filtration rate, GFR), interpretation can be complicated. To ease the interpretation of the two measurements, we propose three new tools: First, we developed a new formula for adjusting s-MMA to an eGFR of 100 mL/min/1.73 m² (s-MMA₁₀₀). The formula was s-MMA₁₀₀ = [(eGFR/100)^0.549] × s-MMA. It was derived from the median relationship between s-MMA and estimated GFR (eGFR) in an ambulant patient population of 4342 individuals, where eGFR was calculated according to the EKFC equations. S-MMA₁₀₀ was not associated with eGFR in a US test population of 6852 individuals. Second, we constructed a combined reference range for s-MMA₁₀₀ and s-cobalamin from data in a healthy reference population (n = 495 individuals). Third, we proposed a new cobalamin deficiency index, CDI = s-cobalamin/s-MMA₁₀₀, and studied the effect of different decision limits on the prevalence of positive test results in a patient population. Using the 2.5 percentile of CDI in the reference population as a decision limit gave a prevalence of 5.2% positive test results in the patient population. However, as a gold standard for cobalamin deficiency does not exist, we were unable to study the diagnostic accuracy of the CDI. Therefore, the true diagnostic accuracy of these tools is yet unknown and should be investigated.

Backgrounds: Serum thyroglobulin immunometric assays (sTg) are crucial for monitoring differentiated thyroid cancer (DTC) treatment. However, challenges such as anti-thyroglobulin autoantibodies (TgAb) and assay variability hinder evaluations. This study assessed four sTg methods-three second-generation (Architect, Access, Elecsys) and one first-generation (Immulite)-following Clinical and Laboratory Standards Institute (CLSI) and American Thyroid Association (ATA) guidelines.

Methods: The study compared sTg_(Architect), sTg_(Access), sTg_(Elecsys), and sTg_(Immulite). Precision was evaluated per CLSI EP05-A3, while the lower limits of detection (LLD) were assessed using EP17-A2. Passing-Bablok and Bland-Altman analyses were conducted as per EP09c, and semi-quantitative comparisons used Kappa statistics.

Results: The second-generation sTgs (Architect, Access, Elecsys) exhibited satisfactory precision (<7% coefficient of variation, CV%), unlike sTg_(Immulite), which showed significant deviations and inadequate sensitivity for DTC recurrence (Limit of quantitation, LoQ = 4.59 μg/L). Second-generation sTgs had strong correlations (r > 0.884) across all concentration ranges (≤1, 1-10, >10 μg/L), with biases (slope: 1.131-2.027). sTg_(Immulite) correlated well with second-generation methods for concentrations >10 μg/L (r > 0.945) but less so for <10 μg/L (r < 0.642). TgAb significantly impacted sTg_(Immulite). Kappa statistics revealed strong agreement among second-generation methods (κ > 0.800) but lower concordance with sTg_(Immulite), especially in TgAb(+) samples (κ: 0.562-0.653). Agreement ratios were high for second-generation methods (0.667-1.000) but variable for sTg_(Immulite), particularly at lower concentrations and in TgAb(+) cases (0.097-0.727).

Conclusions: sTg_(Immulite) did not meet LLD and precision criteria for DTC monitoring, facing issues with TgAb interference. Second-generation sTgs demonstrated consistent performance across all concentrations.

Creatinine is a widely used clinical biomarker in adult and pediatric patients to estimate kidney function and glomerular filtration rate. There are however few recent studies that have addressed method performance in the creatinine range relevant for children. This study aimed to describe measurement performance in the pediatric concentration range by comparing commonly used enzymatic methods on four platforms: Abbott Alinity, Radiometer ABL800, Roche Cobas and Siemens Atellica, to the reference method isotope dilution mass spectrometry (IDMS). A secondary aim was to compare the Roche enzymatic methods by using dilutions of control sera issued by the Nordic Association of Clinical Chemistry. We found varying accuracy of the creatinine methods in the low concentration range. The relative difference between platforms, in an investigated range below 75 µmol/L, decreased as creatinine concentration increased. Using an absolute factor to correct for method bias as recommended by one of the manufacturers could hamper measurement trueness in the low concentration range. The in vitro diagnostic industry and stakeholders should strive towards creatinine measurement agreeability. Attention to the pediatric concentration range is needed when correcting for method bias.

Crystals in urinary sediment are commonly recognized structures, typically identified by a combination of crystal morphology and urine pH. In this paper, we present the first reported case of EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidene) crystals, the primary metabolite of methadone, in a 67-year-old male with hepatorenal syndrome. Routine urinalysis revealed numerous needle-shaped crystals, which prompted further investigation. Advanced techniques, including Raman spectroscopy and mass spectrometry, confirmed the crystals to be EDDP. This case highlights the diagnostic challenge posed by drug-induced crystalluria, particularly in the context of complex comorbidities and chronic opioid therapy. Early recognition and identification of such crystals are crucial to preventing further kidney injury, emphasizing the importance of meticulous urine sediment analysis in clinical practice. This report broadens the spectrum of drugs known to induce crystal formation.

This study assessed the reliability of Roche Accu-Chek Inform II glucometers in a real-world setting. A retrospective analysis was conducted on 6,695 paired results. Capillary samples were tested using Roche Accu-Chek Inform II glucometers, while venous samples were analyzed using Roche Cobas c503/702 analyzers. Compliance was assessed using modified criteria based on the ISO 15197 guideline and the CLSI EP09-A3 guideline using Passing-Bablok regression analysis, Bland-Altman plots, and Surveillance Error Grid (SEG) analysis. The overall compliance of glucometer results within ±15% or 0.83 mmol/L (15 mg/dL) of the reference method was 81.5%, below the acceptance criterion of 94.6%. SEG analysis showed that 90.3% of the paired results fell within the No-risk zone, with less than 0.001% in the moderate/lower-risk zone. The Emergency Department results indicated 87.8% overall compliance and 92.2% of pairs falling in the No-risk zone. Based on the regression analysis, the glucometer results showed a positive constant bias of nearly 0.33 mmol/L (6 mg/dL). The Bland-Altman plots showed a positive mean difference of 0.43 mmol/L for results ≤5.55 mmol/L (≤100 mg/dL) and a positive mean percentage difference of 3.77% for results >5.55 mmol/L (>100 mg/dL), within the permissible deviation. The compliance values ranged from 76.0% to 90.3% for clinical concentration groups, with the highest compliance found between >16.65-22.20 mmol/L (>300-400 mg/dL). The Accu-Chek Inform II glucometers demonstrated in real-world reliability, with most results falling within acceptable risk categories. However, compliance still needs improvement, so manufacturers should assess opportunities for advancement.

β-hydroxybutyrate (BHB) is recommended as a measure of ketosis and is often assessed by capillary samples on point-of-care (POC) meters. However, liquid chromatography tandem mass spectrometry (LC-MS/MS) is considered the gold standard for assessing venous samples. The POC device KetoSure^TM is recommended only for capillary samples from finger pricks. So far, KetoSure^TM has not been compared to LC-MS/MS just as it has not been evaluated if the sampling site influences the BHB concentration. Blood samples were collected from 16 healthy, fasting individuals before and after ingestion of ketone monoester. BHB concentrations were measured in capillary samples from the earlobe and fingertip, and in venous blood using KetoSure^TM. Venous plasma samples were collected for BHB quantification using LC-MS/MS. No sign of significant difference between values of BHB measured from the two capillary sampling sites were found. Interestingly, significantly higher values of BHB were measured in capillary samples compared to venous samples reflecting a systematic proportional relationship. No systematic difference was observed in the measured BHB concentrations when comparing KetoSure^TM and LC-MS/MS results: However, a significant mean bias of 32% reflects a skewness at very low BHB concentrations. In conclusion, capillary BHB concentration did not exhibit variation between the earlobe and fingertip. Conversely, a significant bias was observed between venous and capillary blood and between the POC and LC-MS/MS methods. It is recommended that caution be exercised if individual monitoring of BHB changes encompasses both capillary and venous sampling.

Obesity alters lipid and carbohydrate metabolism, which has an impact on micronutrient status. Zinc affects lipid and glucose metabolism while also acting as an anti-inflammatory and antioxidant in various physiological processes. It has a direct effect on the insulin-signaling system and acts as an insulin mimic. In this study we predicted that zinc deficiency in obese Serbian adults affects anthropometric parameters, lipid and glucose metabolic profiles, inflammation, and atherosclerotic markers. We conducted a case-control study with 31 adult obese individuals and 31 controls. Different methods were used to determine the values of anthropometric and biochemical parameters. Obese participants had significantly decreased serum zinc levels compared to controls (p < .01). In obese subjects, there is a significant negative correlation between zinc and body weight (ρ = -0.324, p < .05), body mass index (ρ = -0.351, p < .05), body fat mass (%) (ρ = -0.431, p = .006), and triglycerides (ρ = -0.317, p < .05), as well as a positive correlation between zinc and high-density lipoproteins (ρ = +0.453, p < .01) and lipoprotein (a) (ρ = +0.417, p < .01). Atherosclerotic index and lipoprotein (a) were significantly related to zinc (p = .0022 and p = .0016, respectively) independently of each other in obese subjects. Our results suggest that the determination of zinc levels in obese persons and their correlation with anthropometric and metabolic parameters could help in the identification of individuals at higher risk for cardiovascular disease.

Hospitalized stroke patients are at high risk of developing circadian disruption due to lack of natural sunlight. This may affect the circadian rhythm of the calcium metabolism. This study is a secondary explorative analysis from a Randomized Controlled Trial. Acute stroke patients requiring a minimum of two weeks of rehabilitation were randomized to an Intervention unit (IU) equipped with naturalistic light or a Control unit (CU) with standard indoor lighting. Blood was drawn across 24 h at inclusion and discharge in 45 patients, 25 from the IU and 20 from the CU. Calcium showed significant rhythmicity at inclusion and discharge in both groups. Alkaline phosphatase, parathyroid hormone (PTH), and Vitamin D exhibited no significant rhythmicity at inclusion or discharge in either group while phosphate exhibited rhythmicity at discharge in the CU. PTH levels were elevated in the CU group compared to the IU group at time of discharge. Of the measured parameters, only calcium exhibited circadian rhythmicity after stroke. Naturalistic light did not have any influence on the rhythmicity, indicating that light may not be the main circadian regulator of the circadian oscillations that regulate calcium metabolism. PTH seems to be decreased by naturalistic light.