Reference Intervals In Healthy Adults Research Articles

Reference intervals for serum creatinine and urea in the adult western Sudanese population

Introduction: Serum creatinine and urea levels are affected by numerous factors such as ethnicity, environment, age, sex, and anthropometric measurements. The Clinical and Laboratory Standards Institute (CLSI) recommends that each laboratory should establish its own reference intervals for biochemistry and haematology. There are no local reference intervals for serum creatinine and blood urea in Sudan; instead, intervals derived from worldwide research are used. The purpose of this study was to determine the blood urea and serum creatinine reference intervals for healthy adults in the Western Sudanese population.
 Method: Randomly selected adult Sudanese residents of Al Fashir City who were from the Western Sudan states of Kordofan and Darfur were the subjects of a cross-sectional study conducted in September and October 2018. We recruited 153 participants. After giving their consent, they were evaluated using a questionnaire that collected medical history and demographic information. We used standard techniques to measure blood pressure, body mass index, urea, and creatinine. Kolmogorov-Smirnov tests were used to assess the distributions of the creatinine and urea values, and reference intervals calculated. T-tests were used to investigate differences of mean creatinine and urea levels by sex and age. IBM SPSS Statistics version 25 was used to analyse the data and p ≤ 0.05 was considered significant.
 Results: Overall, the reference intervals (Mean±1.96*SD) for serum creatinine and urea levels were 0.45-0.92 mg/dL and 7.6-27.9 mg/dL respectively, compared to international reference intervals adopted from the American Board of Internal Medicine (ABIM) serum creatinine (males 0.7-1.3, females 0.5-1.1 mg/dL) and blood urea (17.12-42.8 mg/dL for both sexes) and The Western Sudanese population’s mean serum creatinine and urea levels were, respectively, 0.69 mg/dL and 17.8 mg/dL. Male sex was associated with higher levels of both creatinine and urea (p<0.001).
 Conclusion: This study documented lower reference intervals for creatinine and urea in the Western Sudanese population.

Reference Intervals of Haematological Parameters for Apparently Healthy Adults in Northeast Ethiopia.

Clinical laboratory reference intervals play a vital role in evaluating overall well-being, tracking the progression of diseases, and detecting potential harmful effects and complications. Despite evidence revealing disparities, many African nations currently rely on reference intervals for blood analysis obtained mainly from Western populations. This practice increases the risk of misidentifying and misdiagnosing healthy individuals. The aim of this study was to establish common hematological parameters reference intervals for healthy adults in Northeast Ethiopia. This community-based cross-sectional study consisted of 328 individuals who were presumed to be in good health. To assess their blood-related characteristics, blood samples were collected and analyzed using the advanced Dirui BF-6500 analyzer, along with serological testing. In accordance with guidelines provided by the Clinical and Laboratory Standards Institute, the study employed a non-parametric approach to calculate the medians and 95% confidence intervals. To explore potential variations between males and females, a statistical test known as the Mann-Whitney U-test was used to compare the reference intervals. The established reference intervals were: white blood cells 3.5-11.3×109/L; red blood cells 4.0-6.1×1012/L; hemoglobin 11.2-17.5g/dL; hematocrit 35.4-52.0%; MCV 77.9-93.8fl; MCH 24.7-32.0pg; MCHC 306-349g/L; RDW-CV 12.1-13.8% and platelet 131-391×109/L. The reference values of monocytes, eosinophils, red blood cells, hemoglobin, hematocrit and RDW-CV in males were higher than females, while females had significantly higher platelet counts compared to males. The reference intervals discovered differed from the reference intervals now in use, those mentioned in earlier research in Ethiopia or other African nations, as well as those conducted on Western populations. In the adult demographic of Northeast Ethiopia, specific reference intervals for commonly observed hematological parameters were established, tailored to the local community. Consequently, these reference intervals hold the potential to enhance informed decision-making within this population, by providing valuable guidance when interpreting laboratory test outcomes.

Routine clinical chemistry and haematological test reference intervals for healthy adults in the Bhutanese population.

Laboratory medicine plays a critical role in the modern healthcare system, and it is reported to influence 60-70% of clinical decision makings. The quantitative laboratory test results are interpreted by comparing to the Reference Intervals (RIs) and therefore the use of appropriate RIs is critical. Clinical laboratories in Bhutan have been randomly using RIs from textbooks and manufacturer's package inserts without even verifying their applicability and therefore lessening their contribution to clinical decision makings. To improve the healthcare service delivery in Bhutan, this study aims to establish routine clinical chemistry and haematological test RIs for healthy adults in the Bhutanese population. Out of 1150 (male, n = 570; female, n = 580) healthy Bhutanese adults listed for the study through a simple random sampling technique, 1002 (male, n = 405; female, n = 597) individuals were assessed and 815 (male, n = 372; female, n = 443) individuals were enrolled in the study. An adequate volume of venous blood was drawn from these participants with the use of standard phlebotomy technique for clinical chemistry and haematological analysis. The laboratory data were analysed with the use of statistical methods recommended by the International Federation of Clinical Chemistry and Laboratory Medicine and Clinical and Laboratory Standards Institute. After excluding the test results indicating underlying pathology and statistically detected outliers, a maximum of 775 (male, n = 346; female, n = 429) and 784 (male, n = 351; female, n = 433) individuals test values were eligible for clinical chemistry and haematology RIs establishment respectively. Statistically, there were no significant differences between age groups of same-sex for both test categories; however, significant differences between sex were observed for various test parameters in both test categories. Our RIs are generally comparable to other published literature. The established RIs are applicable to all the adult Bhutanese population; however, clinical laboratories should validate the transference of these RIs before using them for clinical purposes.

Chitinase-3-like protein 1: reference interval of a healthy population and its diagnostic value for liver fibrosis in Pakistan

<p><strong>Background and Objective:</strong> Chitinase-3-like protein 1 (CHI3L1) is an upcoming biomarker for the diagnosis of liver fibrosis. The reference intervals (RIs) for CHI3L1 have not been established in the Pakistani population. Thus, this study aimed to determine the RIs in our population and the cut-off value for diagnosis of hepatic fibrosis.</p>
 <p><strong>Methods:</strong> This is a cross-sectional study. A total of 408 participants (202 healthy and 206 diagnosed liver fibrosis cases) were recruited. Serum CHI3L1 level was measured on CHI3L1 kits (Proprium Biotech Co. Ltd) by manual enzyme-linked immunosorbent assay. The RIs were estimated by percentile and working normal method.</p>
 <p><strong>Results:</strong> The distribution of CHI3L1 values showed no remarkable variation with gender and age. The 95% RI of CHI3L1 was 12.80-81.80 ng/ ml in healthy Pakistani subjects and the cut-off for the diagnosis was 102.12 ng/ml in hepatic fibrosis cases.</p>
 <p><strong>Conclusion:</strong> The RIs in healthy adults and the cut-off for the diagnosis of hepatic fibrosis of serum CHI3L1 were determined in a selective adult Pakistani population. This will be a useful reference for further local and international studies.</p>

Distribution of urinary N-acetyl-beta-D-glucosaminidase and the establishment of reference intervals in healthy adults.

BackgroundUrinary N‐acetyl‐beta‐D‐glucosaminidase (NAG) plays an important role in the early diagnosis and progression of diseases related to renal tubular injury. We detected the urinary NAG concentration, assessed the preliminary statistics of its distribution, and established reference intervals for healthy adults in China using the rate method.MethodsA total of 1,095 reference individuals (aged 20 to 79 years) met the requirements for inclusion in this study. Urinary NAG concentrations were detected using an AU5800 automatic biochemical analyzer with its matched reagents. The Kolmogorov‐Smirnov test was used to analyze the normality of the data. According to the guidelines of C28‐A3 and WS/T 402‐2012, the reference intervals of urinary NAG were established using the nonparametric percentile method (unilateral 95th percentile).ResultsThe urinary NAG data showed a non‐normal distribution. The distribution of urinary NAG was significantly different by sex and age. Therefore, the reference intervals of urinary NAG were established using the rate method: males (aged 20–59 years) <19.4 U/L (90% CI: 18.0–20.3 U/L); males (aged 60–79 years) <22.3 U/L (90% CI: 20.2–22.6 U/L); females (aged 20–59 years) <15.7 U/L (90% CI: 15.2–16.5 U/L); and females (aged 60–79 years) <21.4 U/L (90% CI: 20.3–22.3 U/L).ConclusionsWe established preliminary reference intervals of urinary NAG for healthy adults in China to provide guidance for health screening, auxiliary diagnosis, and treatment monitoring of renal tubule‐related diseases.

Haematological reference intervals for healthy adults in Bamenda, Cameroon.

BackgroundIn the era of evidence-based medicine, haematological reference intervals are essential for the interpretation of data for clinical decision-making, monitoring of treatment and research. It is not uncommon that reference intervals used in most African countries have been obtained from published scientific literature, textbooks, reagent/instrument manuals.ObjectiveThe aim of this study was to determine haematological reference intervals of healthy adults in Bamenda, Cameroon.MethodsThis was a cross-sectional study conducted between June and November 2015. Participants were voluntary blood donors at the Blood Bank Service of the Regional Hospital Bamenda aged between 18 and 65 years. The mean, median and standard deviation of the mean were calculated for each haematological parameter. The 95th percentile reference intervals were determined using the 2.5th and 97.5th percentile. The differences between gender for all the parameters were evaluated using the Kruskal-Wallis test. Significance was determined at the 95% confidence level.ResultsOut of a total of 340 participants, 202 (59.4%) were men and 138 (40.6%) were women. The median red blood cell, haemoglobin, haematocrit and mean cell haemoglobin concentration were significantly higher in men than women (p < 0.001). The median white blood cell, absolute lymphocytes count, absolute granulocytes and platelet counts for men were significantly lower than those for women (p < 0.011).ConclusionWe propose that the present established haematological reference intervals in this study should be used for clinical management of patients and interpretation of laboratory data for research in Bamenda.

Establishing hematological reference intervals in healthy adults: Ravansar non-communicable disease cohort study, Iran.

It is necessary to establish hematological reference intervals (RIs) in each population to improve disease management and healthcare quality. This study aimed to establish age- and sex-specific hematological RIs in a healthy adult Kurdish population and evaluate the influence of select lifestyle factors. Hematological parameters were studied in 6518 individuals (3006 females, 3512 males) from Ravansar Non-Communicable Disease (RaNCD) cohort study. Hematological parameters were measured by Beckman Coulter HmX Analyzer. After combined application of exclusion criteria and statistical outlier removal, RIs for all partitions were calculated using nonparametric methods. The present study established hematological RIs for 14 parameters in a healthy adult Iranian population. Reference values for some analytes demonstrated significant age- and sex-specific differences and were slightly different when compared to RIs determined in other populations. Furthermore, the current smokers had higher levels of white blood cells (WBCs), red blood cells (RBCs), hemoglobin, hematocrit, mean corpuscular hemoglobin (MCH), and mean corpuscular volume than ex- and nonsmokers. Also, in the presence of high physical activity, elevated levels of RBC, hemoglobin, hematocrit, monocytes, and MCH were observed, as well as lower WBC levels. Further, a significant positive association was observed between body mass index (BMI) and WBC, red cell distribution width, and plateletcrit levels. Our study suggests hematological parameters are influenced by age, sex, and lifestyle factors such as physical activity and BMI. Additionally, discrepancies when compared to other population studies suggest that ethnic-specific differences need to be considered when establishing RIs for hematological parameters.

Determination of Hematological Reference Intervals for Healthy Adults in Northeast Ethiopia.

Hematological reference interval is the range between two reference values that are used for inter-pretation of test results. It is affected by various physiological and environmental factors; thus, locally derived hematological reference values are essential for accurate diagnosis and treatment of patients. The main goal of this study was to establish hematological reference intervals for healthy adults at Kemise, Northeast Ethiopia. A cross-sectional study was conducted from January to April, 2019, with 170 male and 159 female apparently healthy adult blood donors at Kemise Blood Bank. A structured pretested questionnaire was used for socio demographic and clinical data collection. About 4 mL of blood was collected in an EDTA test tube and analyzed using Sysmex XP-300 to enumerate the hematological parameters. The data were collected and entered into Epi-Inf7 and then transferred to SPSS version 20 for analysis. Dixon and Reed 1/3 rule was used for outlier detection. Mann-Whitney U test was used to determine reference intervals. Harris and Boyd test were used to determine the reference intervals that need partition. The 2.5th and 97.5th percentiles were determined non-parametrically with 95% confidence interval. The 2.5th - 97.5th percentiles reference intervals for red blood cell males: 3.9 - 6 x 1012/L, females: 3.3 - 5.3 x 1012/L; hemoglobin males: 12 - 17.9 g/dL, females: 10.5 - 16.3 g/dL; and hematocrit males: 34.8 - 51.4%, females: 30.2 - 47%. The combined reference intervals for both genders, were mean corpuscular volume: 77.1 - 95.5 fL, mean corpuscular hemoglobin: 25.6 - 34 pg, mean corpuscular hemoglobin concentration: 31.5 - 36.7 g/dL, red cell distribution width: 11.3 - 15.4%, white blood cells: 3.1 - 10.6 x 109/L, lymphocytes: 1 - 3.7 x 109/L, mixed: 0.3 - 1.7 x 109/L, neutrophils: 1.4 - 7 x 109/L, and platelets: 136 - 425 x 109/L. The established reference intervals in this study were different from previous studies which were conducted in different regions of Ethiopia or African countries or in Caucasian population, and in text books. The RBC, PCV, and Hgb reference intervals were different in gender. So, using of locally determined reference interval is essential.

Distribution of serum amyloid A and establishment of reference intervals in healthy adults.

BackgroundSerum amyloid A (SAA) plays a critical role in acute or chronic and is used in clinical laboratories as an indicator of inflammation. The elevated SAA is closely related to inflammation‐mediated diseases, such as liver diseases, autoimmune diseases, metabolism‐related diseases, amyloidosis, and tumors. However, there is no unified population reference interval for SAA. This study aimed to investigate the distribution of SAA in healthy Chinese adults 20‐79 years of age and to establish its population reference interval.MethodsA total of 2365 healthy subjects met the requirements of this study. The levels of SAA were detected using an AU5821 automatic biochemical analyzer and its original reagents. According to the recommended methods of CLSI C28‐A3 and WS/T 402‐2012, the population reference interval of SAA was established using the unilateral 95th percentile (P95), and the 90% confidence interval of upper limits was calculated.ResultsThe distributions of SAA levels were not significantly different between sexes (P> .05) and also did not differ by age (P> .05). Therefore, the population reference interval for SAA was established as an upper limit of 11.0 mg/L (90% confidence interval: 9.3‐12.3 mg/L) by using the method of latex immunoturbidimetry.ConclusionsSerum amyloid A is closely related to the occurrence and progression of various diseases. The preliminary establishment of a population reference interval for SAA can fully exert its potential clinical value.

Establishment of hematological reference intervals for healthy adults at Tribhuvan University Teaching Hospital, Kathmandu, Nepal

Establishment of hematological reference intervals for healthy adults at Tribhuvan University Teaching Hospital, Kathmandu, Nepal

Serum steroid profiling by isotopic dilution-liquid chromatography–mass spectrometry: Comparison with current immunoassays and reference intervals in healthy adults

Background The simultaneous, rapid and reliable measurement of a wide steroid panel is a powerful tool to unravel physiological and pathological hormone status. Clinical laboratories are currently dominated by high-throughput immunoassays, but these methods lack specificity due to cross-reactivity and matrix interferences. We developed and validated an isotopic dilution-liquid chromatography–tandem mass spectrometry (ID-LC–MS/MS) method for the simultaneous measurement of cortisol, corticosterone, 11deoxycortisol, androstenedione, deoxycorticosterone (DOC), testosterone, 17OHprogesterone, dehydroepiandrosterone (DHEA) and progesterone in serum, and compared it to routine immunoassays employed in our laboratory. We also established adult reference intervals in 416 healthy subjects. Methods 0.9 ml of serum were spiked with labelled internal standards (IS) and extracted on C18 cartridges. Eluate was injected into a two-dimensional LC-system, purified in a perfusion column and separated on a C8 column during a 21 min gradient run. Analytes were revealed by atmospheric pressure chemical ionization (APCI) followed by multiple reaction monitoring (MRM) analysis. Results Of the four immunoassays compared with the ID-LC–MS/MS method, only the results of ElecsysE170 for cortisol, testosterone in males and progesterone > 1 ng/ml were in agreement with ID-LC–MS/MS. ElecsysE170 for testosterone in females and progesterone < 1 ng/ml, Immulite2000 for androstenedione, DSL-9000 for DHEA and 17OHP Bridge for 17OHprogesterone, respectively, showed poor agreement. Reference intervals and steroid age and fertility related fluctuations were established. Conclusion Our ID-LC–MS/MS method proved to be reliable and sensitive in revealing steroid circulating concentrations in adults and in highlighting the limits of routine immunoassays at low concentrations.

CLSI-derived hematology and biochemistry reference intervals for healthy adults in eastern and southern Africa.

BackgroundClinical laboratory reference intervals have not been established in many African countries, and non-local intervals are commonly used in clinical trials to screen and monitor adverse events (AEs) among African participants. Using laboratory reference intervals derived from other populations excludes potential trial volunteers in Africa and makes AE assessment challenging. The objective of this study was to establish clinical laboratory reference intervals for 25 hematology, immunology and biochemistry values among healthy African adults typical of those who might join a clinical trial.Methods and FindingsEqual proportions of men and women were invited to participate in a cross sectional study at seven clinical centers (Kigali, Rwanda; Masaka and Entebbe, Uganda; two in Nairobi and one in Kilifi, Kenya; and Lusaka, Zambia). All laboratories used hematology, immunology and biochemistry analyzers validated by an independent clinical laboratory. Clinical and Laboratory Standards Institute guidelines were followed to create study consensus intervals. For comparison, AE grading criteria published by the U.S. National Institute of Allergy and Infectious Diseases Division of AIDS (DAIDS) and other U.S. reference intervals were used. 2,990 potential volunteers were screened, and 2,105 (1,083 men and 1,022 women) were included in the analysis. While some significant gender and regional differences were observed, creating consensus African study intervals from the complete data was possible for 18 of the 25 analytes. Compared to reference intervals from the U.S., we found lower hematocrit and hemoglobin levels, particularly among women, lower white blood cell and neutrophil counts, and lower amylase. Both genders had elevated eosinophil counts, immunoglobulin G, total and direct bilirubin, lactate dehydrogenase and creatine phosphokinase, the latter being more pronounced among women. When graded against U.S.-derived DAIDS AE grading criteria, we observed 774 (35.3%) volunteers with grade one or higher results; 314 (14.9%) had elevated total bilirubin, and 201 (9.6%) had low neutrophil counts. These otherwise healthy volunteers would be excluded or would require special exemption to participate in many clinical trials.ConclusionsTo accelerate clinical trials in Africa, and to improve their scientific validity, locally appropriate reference ranges should be used. This study provides ranges that will inform inclusion criteria and evaluation of adverse events for studies in these regions of Africa.

Serum β2-microglobulin measured by immunonephelometry: expression patterns and reference intervals in healthy adults

Serum beta2-microglobulin (beta2m) has been established as a marker of disease activity in malignancies, autoimmune conditions and infections. Despite its important role in prognosis assessment and disease monitoring, relatively few studies are available on its expression in healthy individuals. Furthermore, interpretation of results is hampered by the variety in reference limits due to differences in methodology, sample population and statistics. Serum beta2m concentrations were measured using a microparticle-enhanced immunonephelometric method in 183 healthy blood donors aged 29-75 years. The median beta2m concentration was 1.67 (0.88-2.75) mg/L with no difference between men and women (1.71 mg/L vs. 1.62 mg/L, p<0.07). A linear correlation was found between beta2m and age (p<0.0001), serum concentrations significantly higher in older subjects (1.55, 1.59, 1.70, and 1.87 mg/L in age groups of 29-40, 40-50, 50-60 and 60-75 years, respectively, p<0.0001). Reference intervals obtained by non-parametric estimation after partitioning by age were 1.02-2.46 mg/L vs. 1.29-2.70 mg/L in younger (29-49 years) vs. older (50-75 years) individuals. These data can help standardise beta2m reference limits and support age-adjusted comparisons in clinical studies.

Normal blood cells reference intervals of healthy adults at the Gaza Strip—Palestine

Hematological parameters are affected by different factors that include age, sex, smoking, ethnicity, and environmental altitude. It has been justified that each population must establish its own normal reference intervals to be used in clinical assessments and interpretations. Hematological reference intervals for adults from the Gaza Strip-Palestine have never been addressed. Therefore, this study was designed and aimed at the establishment of normal blood cells reference intervals for healthy adults at the Gaza Strip-Palestine. This study involved 89,491 apparently healthy individuals (from both sexes and from the different governorates of the Gaza Strip) who were referred to the Thalassemia Central Laboratory during the period from September 2000 until February 2008. Complete blood counts were performed. Subjects were categorized into subgroups according to gender, smoking habit, and age (15-18, 19-45, and >45 years old). For each subgroup, descriptive and comparative statistical analysis was performed for hematological parameters. The results showed substantial differences between males and females, between smokers and nonsmokers, and between the different age groups. Moreover, reference intervals derived from our population are markedly shifted downward as compared with Western European and American populations. It was concluded that separate and region-specific reference intervals based on gender, smoking, and age for the Palestinian population at the Gaza Strip should be generalized for clinical laboratories and clinical practitioners, which could help in interpreting laboratory hematological tests more specifically, and potentially develop the quality of medical care provided to patients.

タンパク分画用の新規セルロースアセテート膜，セレカ‐ＶＳＰの性能評価‐自動電気泳動装置「ＡＥＳ６３０」による分析‐

New cellulose acetate membrane SELECA-VSP was prepared as a substitute for the conventional cellulose acetate membrane SEPARAX-SP, which has been widely used for serum protein electrophoretic fractionation. We evaluated the separating quality of this new membrane, using fully automated serum protein electrophoresis system AES630.Correlation of serum protein fraction values (percentage composition) between the two membranes, those patterns of sera from patients with protein disorders, and reference intervals in healthy adults were analyzed. In addition, the electrophoretic determinations of amylases and glycoproteins were tested.The correlation coefficients of the each electrophoretic fraction between SELECA-VSP and of SEPARAX-SP were greater than 0.97. Reference intervals in healthy adults on SELECA-VSP and on SEPARAX-SP were nearly equal.The separating performance of SELECA-VSP were rather higher as compared to SEPARAX-SP for serum protein electrophoretic fractionation, amylase isoenzymes and glycoproteins.The utility and effectiveness of a new membrane SELECA-VSP can be best appreciated on the basis of our experimental results.

Serum protein electrophoresis by CZE 2000 clinical capillary electrophoresis system

We compared the automated Paragon 2000 clinical capillary zone electrophoresis (CZE) system with two manual methods, agarose electrophoresis (AGE) and cellulose acetate electrophoresis (CAE). Reference intervals in healthy adults were determined for each method. When compared with AGE and CAE, CZE gave substantially higher reference values for the alpha1-globulin fraction. With CZE, within-run precision for fraction quantitation was between 0.5% (albumin) and 4.1% (alpha1-globulin). Total precision was between 0.8% (albumin) and 5.3% (beta-globulin). Data obtained from CZE showed poor linear correlation with results obtained by AGE but good linear correlation with data from CAE. Analysis of serum from patients with inter alia inflammation, nephrotic syndrome, or polyclonal gammopathy showed that clinical information obtained by CZE is comparable with information obtained by AGE and CAE. We conclude that CZE offers a clinically reliable alternative to AGE and CAE and has the advantages of automation, higher precision, and faster turnaround time.

Radioimmunoassay of the carboxyterminal propeptide of human type I procollagen

Type I collagen is the most abundant collagen type in soft tissues and the only type found in mineralized bone. We established a rapid equilibrium radioimmunoassay for the carboxyterminal propeptide of human type I procollagen (PICP), to be used as an indicator of the synthesis of type I collagen. We isolated type I procollagen from the medium of primary cultures of human skin fibroblasts, digested the protein with highly purified bacterial collagenase, and purified PICP by lectin-affinity chromatography, gel filtration, and ion-exchange separation on HPLC. The purity of the protein was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by N-terminal amino acid sequencing of its component chains. The final radioimmunoassay was established with polyclonal rabbit antibodies. Material antigenically related to PICP is readily detected in human serum. There is only one form of the serum antigen, its molecular size and affinity to the antibodies being similar to those of the isolated propeptide. Intra- and interassay CVs are 3% and 5%, respectively. Preliminary reference intervals for healthy adults (18 to 61 years of age) are 38-202 micrograms/L for men and 50-170 micrograms/L for women: in men the concentration is inversely related to age. The serum antigen is stable during storage and after repeated thawing.

Adjusted ionized calcium (at pH 7.4) and actual ionized calcium (at actual pH) in capillary blood compared for clinical evaluation of patients with disorders of calcium metabolism

We report results for adjusted ionized calcium (at pH 7.4) and actual ionized calcium (at actual pH) in capillary blood from 183 patients with disorders of calcium metabolism (primary hyperparathyroidism, secondary hyperparathyroidism of malabsorption, primary hypoparathyroidism, Paget's disease, acromegaly, hypercalcemia of malignancy, osteoporosis, sarcoidosis, idiopathic hypercalciuria, and familial hypocalciuric hypercalcemia). The correlation and the equation for the linear regression between adjusted ionized calcium (y) and actual ionized calcium (x) were y = 1.011x + 0.005 mmol/L, r = 0.992, Sy,x = 0.021 mmol/L. Results were similar within each diagnostic group. Consistent agreement between adjusted and ionized calcium was observed in 96.7% of patients representing a variety of the most frequently encountered disorders of calcium metabolism. Thus we find adjusted ionized calcium to be as useful as actual ionized calcium for evaluation of patients with such disorders. Adjusted ionized calcium may therefore also be a logical choice for establishing agreement between laboratories for reference intervals in healthy adults.