Biological Variation in Urinary Excretion of Pyridinium Crosslinks: Recommendations for the Optimum Specimen

Author(s):  
M Panteghini ◽  
F Pagani

We assessed the analytical and biological variation of pyridinium crosslinks in early morning, 2 h fasting, and 24 h urine specimens from 14 healthy adults over a 1 month period. The results were expressed both in terms of pyridinoline concentration and pyridinoline/creatinine ratio. The data obtained were used to select the optimum specimen for clinical purposes. We found that: ( a) early morning specimens are preferred; ( b) results should be expressed as pyridinoline/creatinine ratio; ( c) reference intervals should be stratified according to gender; ( d) the necessary analytical imprecision (CV≤ 9%), derived from biological variation, is not easily achieved by current methods; ( e) the difference between serial results from an individual must be > 50% to be statistically significant; and ( f) assessment of risk for osteoporotic fracture by means of the pyridinium crosslink assay would, in a significant number of patients, require analysis of multiple urine specimens.

1989 ◽  
Vol 35 (4) ◽  
pp. 560-563 ◽  
Author(s):  
I Stolarek ◽  
J E Howey ◽  
C G Fraser

Abstract The analytical, within-subject, and between-subject components of variation of N-acetyl-beta-D-glucosaminidase (NAG) were estimated from duplicate assays of 10 timed first morning and 10 untimed urine specimens collected from each of 15 ostensibly healthy individuals. Results were expressed in terms of activity, NAG/creatinine ratio, and excretion rate. Current analytical methods can achieve desirable performance standards. NAG has little individuality, and conventional population-based reference intervals are therefore useful. In view of the practicability and relatively low within-subject variation, for routine clinical purposes we prefer assay of NAG in first morning urine, expressing the results in terms of activity. Using the results of assays of different specimens, we found that the correlation between urinary albumin and NAG varied considerably, owing to the large intrinsic variability of both analytes; this might explain previous conflicting results.


1987 ◽  
Vol 33 (11) ◽  
pp. 2034-2038 ◽  
Author(s):  
J E Howey ◽  
M C Browning ◽  
C G Fraser

Abstract To investigate the optimum specimen for quantifying low, but abnormal, concentrations of albumin in urine, we assessed the analytical and biological components of variation in first morning, random untimed, and 24-h urine specimens from 11 apparently healthy individuals. The results were expressed in terms of albumin concentration, albumin/creatinine ratio, and albumin excretion rate. Analytical methods generally can meet the analytical goal of CV less than or equal to 18%. For reasons detailed herein, we prefer measurement of the albumin concentration in the first morning specimen. Expressing results as an albumin/creatinine ratio has little advantage. Albumin concentrations in first morning urines from 16 diabetic subjects showed larger intra-individual variation than for nondiabetic subjects but clearly fell into two groups: those with consistently normal albumin concentrations in urine and those with abnormal concentrations in some specimens. The intrinsic biological variation of the latter group means that the ideal 100% nosological specificity cannot be achieved with any cutoff point without inclusion of a large proportion of the former. Qualitative testing with a latex-agglutination technique also demonstrates this problem. Use of data on biological variation allows development of an appropriate clinical strategy to investigate diabetic patients.


Author(s):  
Natasha Ansari ◽  
Eric Johnson ◽  
Jennifer A. Sinnott ◽  
Sikandar Ansari

Background: Oncology provider discussions of treatment options, outcomes of treatment, and end of life planning are essential to care for patients with advanced malignancies. Studies have shown that despite this, many patients do not have adequate care planning, including end of life planning. It is thought that the accessibility of information outside of clinical encounters and individual factors and/or beliefs may influence the patient’s perception of disease. Aims: The objective of this study was to evaluate if patient understanding of treatment goals matched the provider and if there were areas of discrepancy. If a discrepancy was found, the survey inquired further into more specific aspects. Methods: A questionnaire-based survey was performed at a cancer hospital outpatient clinic. 100 consecutive and consenting patients who had stage IV non-curable lung, gastrointestinal (GI), or other cancer were included in the study. Patients must have had at least 2 visits with their oncologist. Results: 40 patients reported their disease might be curable and 60 reported their disease was not curable. Patients who reported their disease was not curable were more likely to be 65 years or older (P-value: 0.055). They were more likely to report that their doctor discussed the possibility of their cancer getting worse (78.3% VS 55%; P-value 0.024), that their doctor discussed end of life plans (58.3% VS 30%; P- value: 0.01), and that they had appointed a health care decision-maker (86.7% VS 62.5%; P-value: 0.01). 65% of patients who thought their disease might be curable reported that their doctor said it might be curable, compared with only 6.7% of patients who thought their disease was not curable (p < 0.001). Or, equivalently, 35% of patients who thought their disease might be curable reported that their doctor’s opinion was that it was not curable, compared with 93% of patients who thought their disease was not curable (p < 0.001). Patients who had lung cancer were more likely to believe their cancer was not curable than patients with gastrointestinal or other cancer, though the difference was not statistically significant (p = 0.165). Patients who said their disease might be curable selected as possible reasons that a miracle (50%) or alternative medicine (66.7%) would get rid of the cancer, or said their family wanted them to believe the cancer would go away (16.7%) or that another doctor said it would (4.2%). Patients who said their disease might be curable said they did so due to alternative medications, another doctor, or their family. Restricting to the 70 patients who reported their doctors telling them their disease was not curable, 20% of them still said that they personally felt their disease might be curable. Patients below 65 years of age were more likely to disagree with the doctor in this case (P-value: 0.047). Conclusion: This survey of patients diagnosed with stage IV cancer shows that a significant number of patients had misunderstandings of the treatment and curability of their disease. Findings suggest that a notable proportion kept these beliefs even after being told by treating physicians that their disease is not curable.


Author(s):  
Magdalena Kwiatosz-Muc ◽  
Bożena Kopacz

Background: An increasing number of patients included in home mechanical ventilation (HMV) care has been under observation for many years. The study aimed to assess the patients opinion concerning the expected and perceived quality of care in an HMV system and a patient’s satisfaction with care. Methods: In 2017, patients treated with HMV were surveyed in Poland with the modified SERVQUAL questionnaire. Results: One hundred correctly completed surveys were analyzed. Patient Satisfaction Index was high. In every examined area, the expectations were statistically significant larger than the perception of the services. The biggest gap was in the tangibility dimension and the smallest gap was in the empathy dimension. Perceived respect and understanding for a patient’s needs are close to the expectations. Conclusions: The level of satisfaction with health care among patients treated with HMV in majority of investigated components is high. Moreover, the difference between perceived and expected quality of health care in the HMV system was relatively small in the opinion of the patients themselves. Further investigations with alternative methods are needed.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ceylan Bal ◽  
Serpil Erdogan ◽  
Gamze Gök ◽  
Cemil Nural ◽  
Betül Özbek ◽  
...  

Abstract Objectives Calculation of biological variation (BV) components is very important in evaluating whether a test result is clinically significant. The aim of this study is to analyze BV components for copper, zinc and selenium in a cohort of healthy Turkish participants. Methods A total of 10 serum samples were collected from each of the 15 healthy individuals (nine female, six male), once a week, during 10 weeks. Copper, zinc and selenium levels were analyzed by atomic absorption spectrometer. BV parameters were calculated with the approach suggested by Fraser. Results Analytical variation (CVA), within-subject BV (CVI), between-subject BV (CVG) values were 8.4, 7.1 and 4.3 for copper; 4.2, 9.1 and 13.7 for zinc; 7.6, 2.5 and 6.9 for selenium, respectively. Reference change values (RCV) were 30.46, 27.56 and 22.16% for copper, zinc and selenium, respectively. The index of individuality (II) values were 1.65, 0.66 and 0.36 for copper, zinc and selenium, respectively. Conclusions According to the results of this study, traditional reference intervals can be used for copper but we do not recommend using it for zinc and selenium. We think that it would be more accurate to use RCV value for zinc and selenium in terms of following significant changes in recurrent results of a patient.


2005 ◽  
Vol 17 (4) ◽  
pp. 689-698 ◽  
Author(s):  
Shigekiyo Fujita ◽  
Tetsuro Kawaguchi ◽  
Toshiyuki Uehara ◽  
Kazuhito Fukushima

Background: Platelet hyper-aggregability is an important risk factor for leukoaraiosis. In this study we investigated whether aggravation of leukoaraiosis can be controlled by means of long-term correction of platelet hyper-aggregability.Methods:Twenty-one patients with leukoaraiosis and uncorrected platelet hyper-aggregability were compared with 21 controls matched for age, grade of leukoaraiosis and observation period whose platelet hyper-aggregability was corrected. Platelet aggregability was estimated by an optical analytical method with a nine-stage display using two different concentrations each of adenosine diphosphate (ADP) and collagen (the double ADP method).Results:The mean observation period between two magnetic resonance imaging (MRI) scans for both groups was 4.1 years. In the non-corrected group, moderate to severe aggravation of leukoaraiosis was observed in a large number of patients. In the corrected group, only a small number of patients showed generally mild aggravation of leukoaraiosis. The number of patients showing aggravation of periventricular hyperintensity (PVH) was 7 in 21 in the non-corrected group versus 1 in 21 (p=0.022) in the corrected group, and for aggravation of deep white-matter hyperintensity, these values were 9 in 21 versus 4 in 21, respectively. Thus, the difference was more significant if the degree of aggravation was taken into account.Conclusion:The progress of leukoaraiosis is greatly inhibited by long-term correction of platelet hyper-aggregability.


Author(s):  
Shuo Wang ◽  
Min Zhao ◽  
Zihan Su ◽  
Runqing Mu

Abstract Objectives A large number of people undergo annual health checkup but accurate laboratory criterion for evaluating their health status is limited. The present study determined annual biological variation (BV) and derived parameters of common laboratory analytes in order to accurately evaluate the test results of the annual healthcare population. Methods A total of 43 healthy individuals who had regular healthcare once a year for six consecutive years, were enrolled using physical, electrocardiogram, ultrasonography and laboratory. The annual BV data and derived parameters, such as reference change value (RCV) and index of individuality (II) were calculated and compared with weekly data. We used annual BV and homeostatic set point to calculate personalized reference intervals (RIper) which were compared with population-based reference intervals (RIpop). Results We have established the annual within-subject BV (CVI), RCV, II, RIper of 24 commonly used clinical chemistry and hematology analytes for healthy individuals. Among the 18 comparable measurands, CVI estimates of annual data for 11 measurands were significantly higher than the weekly data. Approximately 50% measurands of II were <0.6, the utility of their RIpop were limited. The distribution range of RIper for most measurands only copied small part of RIpop with reference range index for 8 measurands <0.5. Conclusions Compared with weekly BV, for annual healthcare individuals, annual BV and related parameters can provide more accurate evaluation of laboratory results. RIper based on long-term BV data is very valuable for “personalized” diagnosis on annual health assessments.


PEDIATRICS ◽  
1978 ◽  
Vol 62 (5) ◽  
pp. 751-760
Author(s):  
Calvin M. Kunin ◽  
Russell W. Chesney ◽  
William A. Craig ◽  
Albert C. England ◽  
Catherine DeAngelis

Urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) was shown to be reproducible in random urine specimens when expressed as the ratio of NAG to milligrams of urinary creatinine. The enzyme/creatinine ratio in 815 healthy people was relatively constant throughout childhood and adult life except for the first two years after birth and in individuals 56 years or greater. High ratios in the young children may be explained by low urinary creatinine excretion probably related to small body mass and reduced glomerular filtration rate at this age. The ratio was increased in adult uremic patients and children and adults with a variety of neurologic and obstructive lesions of the voiding mechanism. The presence of bacteriuria did not appear to increase the ratio. Significant enzymuria (&gt; 2 SD above the mean for age and sex) was detected in 38 of 81 children with well-characterized renal disease. Among patients with predominantly glomerular disorders there was a close relationship between activity of the disease and enzymuria. In patients with tubulointerstitial disease enzymuria was frequent even in the absence of proteinuria. One of the highest enzyme/creatinine ratios was observed in a child with cystinosis. These studies indicate that NAG enzymuria is a sensitive indicator of activity of renal disease and may prove to be a suitable screening test for significant renal disease or injury in childhood.


2020 ◽  
Author(s):  
Abdurrahman Coşkun ◽  
Sverre Sandberg ◽  
Ibrahim Unsal ◽  
Coskun Cavusoglu ◽  
Mustafa Serteser ◽  
...  

Abstract Background The concept of personalized medicine has received widespread attention in the last decade. However, personalized medicine depends on correct diagnosis and monitoring of patients, for which personalized reference intervals for laboratory tests may be beneficial. In this study, we propose a simple model to generate personalized reference intervals based on historical, previously analyzed results, and data on analytical and within-subject biological variation. Methods A model using estimates of analytical and within-subject biological variation and previous test results was developed. We modeled the effect of adding an increasing number of measurement results on the estimation of the personal reference interval. We then used laboratory test results from 784 adult patients (&gt;18 years) considered to be in a steady-state condition to calculate personalized reference intervals for 27 commonly requested clinical chemistry and hematology measurands. Results Increasing the number of measurements had little impact on the total variation around the true homeostatic set point and using ≥3 previous measurement results delivered robust personalized reference intervals. The personalized reference intervals of the study participants were different from one another and, as expected, located within the common reference interval. However, in general they made up only a small proportion of the population-based reference interval. Conclusions Our study shows that, if using results from patients in steady state, only a few previous test results and reliable estimates of within-subject biological variation are required to calculate personalized reference intervals. This may be highly valuable for diagnosing patients as well as for follow-up and treatment.


2019 ◽  
Vol 19 (1) ◽  
pp. 603-615 ◽  
Author(s):  
Hajime Akimoto ◽  
Tatsuya Nagashima ◽  
Jie Li ◽  
Joshua S. Fu ◽  
Dongsheng Ji ◽  
...  

Abstract. In order to clarify the causes of variability among the model outputs for surface ozone in the Model Intercomparison Study Asia Phase III (MICS-Asia III), three regional models, CMAQ v.5.0.2, CMAQ v.4.7.1, and NAQPMS (abbreviated as NAQM in this paper), have been selected. Detailed analyses of monthly averaged diurnal variation have been performed for selected grids covering the metropolitan areas of Beijing and Tokyo and at a remote oceanic site, Oki. The chemical reaction mechanism, SAPRC99, used in the CMAQ models tended to give a higher net chemical ozone production than CBM-Z used in NAQM, agreeing with previous studies. Inclusion of the heterogeneous “renoxification” reaction of HNO3 (on soot surface)→NO+NO2 only in NAQM would give a higher NO concentration resulting in a better agreement with observational data for NO and nighttime O3 mixing ratios. In addition to chemical processes, the difference in the vertical transport of O3 was found to affect the simulated results significantly. Particularly, the increase in downward O3 flux from the upper layer to the surface after dawn was found to be substantially different among the models. Larger early morning vertical transport of O3 simulated by CMAQ 5.0.2 is thought to be the reason for higher daytime O3 in July in this model. All three models overestimated the daytime ozone by ca. 20 ppbv at the remote site Oki in July, where in situ photochemical activity is minimal.


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