The effect of age, sex and other factors on blood chemistry in health

Delta-S-Cys-Albumin as a Marker of Pediatric Biospecimen Integrity

Blood plasma storage is a crucial element of pediatric biobanking. Improperly stored or handled specimens (e.g., at > -30°C) can result in altered biomolecular compositions that no longer reflects in vivo reality. We report application of a previously developed assay in adults-the ΔS-Cys-Albumin assay, which facilitates estimation of plasma and serum exposure to thawed conditions-to a population of pediatric EDTA plasma samples from patients aged 3-18 years to determine the assay's applicability, estimate its reference range for pediatric samples, and assess the impact of pre-centrifugation delay at 0°C. In addition, the effect of plasma thawed-state exposure to a range of times at 23°C, 4°C, and -20°C on ΔS-Cys-Albumin was evaluated. Using 98 precollected and processed pediatric EDTA plasma specimens, no difference was found in ΔS-Cys-Albumin under conditions of pre-centrifugation delay for up to 10 hours at 0°C. This lack of change allowed us to estimate a pediatric reference range for ΔS-Cys-Albumin of 7.0%-22.5% (mean of 12.8%) with a modest Pearson correlation between ΔS-Cys-Albumin and age (p = 0.0037, R2 = 0.29). ΔS-Cys-Albumin stability in six specimens at 23°C, 4°C, and -20°C was also evaluated. Plateaus in the decay curves were reached by 1 day, 7 days, and 14-28 days at these respective temperatures. The estimated pediatric reference range observed in children was lower than that previously observed in 180 adults of 12.3%-30.6% (mean of 20.0%), and the slope of the age correlation in children was twice as steep as that from adults. ΔS-Cys-Albumin decay curves at 23°C, 4°C, and -20°C were similar to those previously observed in adults. The data reported here support the use of ΔS-Cys-Albumin in evaluating the integrity and overall exposure of pediatric EDTA plasma specimens to thawed conditions. In doing so, they add an important quality control tool to the biobanker's arsenal.

Hematological and Serum Biochemical Reference Intervals for Alphaxalone Sedated Common Marmosets (Callithrix jacchus)

Marmosets are routinely used in biomedical research, therefore there is an increasing need for updated reference intervals calculated using a large sample size, correct statistics, and considering different variables. Hematological and biochemical values from 472 healthy common marmosets sedated with alphaxalone were collected over a ten-year period (2013-2023). The variables assumed to have influenced the blood-based parameters were compared, i.e., sex, age, housing condition, pregnancy, and contraceptive use. Reference intervals were calculated based on observed percentiles without parametric assumptions, and with parametric assumptions following Box-Cox transformation. Juvenile marmosets showed increased ALP, phosphate, WBC, lymphocyte count, and basophil count and decreased levels of GGT and Fe compared to adults. Marmosets housed strictly indoors showed increased ALT and GGT levels and decreased levels of total bilirubin and neutrophil count compared to marmosets housed with outdoor access. Pregnant marmosets showed increased ALP, total bilirubin, neutrophil count, monocyte count, and basophil count, and decreased levels of AST, ALT, cholesterol, Fe, and lymphocyte count compared to non-pregnant marmosets. Etonogestrel contracepted marmosets showed decreased P-LCR compared to females who were not contracepted. Updated reference intervals will aid researchers and veterinarians in identifying physiological and pathological changes, as well as improve the reproducibility of research in this species.

Current status and challenges in establishing reference intervals based on real-world data

Reference intervals (RIs) are the cornerstone for evaluation of test results in clinical practice and are invaluable in judging patient health and making clinical decisions. Establishing RIs based on clinical laboratory data is a branch of real-world data mining research. Compared to the traditional direct method, this indirect approach is highly practical, widely applicable, and low-cost. Improving the accuracy of RIs requires not only the collection of sufficient data and the use of correct statistical methods, but also proper stratification of heterogeneous subpopulations. This includes the establishment of age-specific RIs and taking into account other characteristics of reference individuals. Although there are many studies on establishing RIs by indirect methods, it is still very difficult for laboratories to select appropriate statistical methods due to the lack of formal guidelines. This review describes the application of real-world data and an approach for establishing indirect reference intervals (iRIs). We summarize the processes for establishing iRIs using real-world data and analyze the principle and applicable scope of the indirect method model in detail. Moreover, we compare different methods for constructing growth curves to establish age-specific RIs, in hopes of providing laboratories with a reference for establishing specific iRIs and giving new insight into clinical laboratory RI research. (201 words).

Effects of sex, age, and body mass index on serum bicarbonate

Rationale

Obesity hypoventilation syndrome (OHS) is often underdiagnosed, with significant morbidity and mortality. Bicarbonate, as a surrogate of arterial carbon dioxide, has been proposed as a screening tool for OHS. Understanding the predictors of serum bicarbonate could provide insights into risk factors for OHS. We hypothesized that the bicarbonate levels would increase with an increase in body mass index (BMI), since the prevalence of OHS increases with obesity.

Methods

We used the TriNetX Research Network, an electronic health record database with de-identified clinical data from participating healthcare organizations across the United States, to identify 93,320 adults without pulmonary or advanced renal diseases who had serum bicarbonate and BMI measurements within 6 months of each other between 2017 and 2022. We used linear regression analysis to examine the associations between bicarbonate and BMI, age, and their interactions for the entire cohort and stratified by sex. We also applied a non-linear machine learning algorithm (XGBoost) to examine the relative importance of age, BMI, sex, race/ethnicity, and obstructive sleep apnea (OSA) status on bicarbonate.

Results

This cohort population was 56% women and 72% white and 80% non-Hispanic individuals, with an average (SD) age of 49.4 (17.9) years and a BMI of 29.1 (6.1) kg/m2. The mean bicarbonate was 24.8 (2.8) mmol/L, with higher levels in men (mean 25.2 mmol/L) than in women (mean 24.4 mmol/L). We found a small negative association between bicarbonate and BMI, with an expected change of -0.03 mmol/L in bicarbonate for each 1 kg/m2 increase in BMI (p < 0.001), in the entire cohort and both sexes. We found sex differences in the bicarbonate trajectory with age, with women exhibiting lower bicarbonate values than men until age 50, after which the bicarbonate levels were modestly higher. The non-linear machine learning algorithm similarly revealed that age and sex played larger roles in determining bicarbonate levels than the BMI or OSA status.

Conclusion

Contrary to our hypothesis, BMI is not associated with elevated bicarbonate levels, and age modifies the impact of sex on bicarbonate.

Admission Dehydration Status Portends Adverse Short-Term Mortality in Patients with Spontaneous Intracerebral Hemorrhage

The impact of dehydration at admission of patients with spontaneous intracerebral hemorrhage (ICH) on short-term mortality remains ambiguous due to scarce data. All of the consecutive patients with spontaneous ICH, who were referred to our neurovascular center in 2018/19, were assessed for hydration status on admission. Dehydration was defined by a blood urea-to-creatinine ratio > 80. In a cohort of 249 patients, 76 patients (31%) were dehydrated at the time of admission. The following factors were significantly and independently associated with increased 30-day mortality in multivariate analysis: “signs of cerebral herniation” (p = 0.008), “initial midline shift > 5 mm” (p < 0.001), “ICH score > 3” (p = 0.007), and “admission dehydration status” (p = 0.007). The results of the present study suggest that an admission dehydration status might constitute a significant and independent predictor of short-term mortality in patients with spontaneous ICH.

Age, sex, and inflammatory markers predict chronic conditions, cardiac disease, and mortality among captive western lowland gorillas (Gorilla gorilla gorilla)

In humans, inflammatory markers predict health risks. As great apes experience many similar conditions, measuring inflammation may provide valuable health information. We examined four serum inflammatory markers in zoo-housed gorillas (n = 48): albumin, CRP, IL-6, and TNF-α. We first analyzed age- and sex-associated patterns, then used multimodel inference to evaluate models with age, sex, and inflammatory markers as predictors of all-cause morbidity, cardiac disease, and mortality. Older gorillas had lower albumin and higher IL-6, and males had higher albumin, lower CRP, and lower TNF-α. All-cause morbidity was best predicted by age, sex, and TNF-α, but the second model containing only age and sex was equivalent. Cardiac disease was best predicted by TNF-α alongside age and sex, with lower levels associated with increased risk. When outliers were removed, the model with TNF-α was second to the model containing only age and sex. Finally, mortality risk was best predicted by the model with only age and sex. Other models containing individual inflammatory markers were within top model sets for each health outcome. Our results indicate that age and sex are robust for predicting all-cause morbidity and mortality risk in gorillas; while models which include individual inflammatory markers also predict risk, they may not improve predictions over age and sex alone. However, given the prevalence of cardiac disease in great apes, these results suggest that TNF-α warrants further investigation. With their potential to provide valuable health information, data on inflammatory markers may contribute to the care and management of gorillas in human care.

Genetically determined hypoalbuminemia as a risk factor for hypertension: instrumental variable analysis

Hypoalbuminemia is associated with vascular endothelial dysfunction and the development of chronic cardiovascular diseases. However, the relationship between serum albumin concentration and blood pressure changes remains controversial. Community-based longitudinal cohort data collected from Korean Genome and Epidemiology Study were used in this study. Hypoalbuminemia was defined as a serum albumin concentration of ≤ 4.0 g/dL. A total of 4325 participants were categorized into control (n = 3157) and hypoalbuminemia (n = 1168) groups. Serum albumin had a non-linear relationship with the risk of hypertension development. A genome-wide association study revealed 71 susceptibility loci associated with hypoalbuminemia. Among susceptibility loci, genetic variations at rs2894536 in LOC107986598 and rs10972486 in ATP8B5P were related to elevated blood pressure. Serum albumin (HR = 0.654, 95% CI 0.521-0.820) and polymorphisms of rs2894536 (HR = 1.176, 95% CI 1.015-1.361) and rs10972486 (HR = 1.152, 95% CI 1.009-1.316) were significant predictors of hypertension development. Increased albumin concentration instrumented by 2 hypoalbuminemia-associated SNPs (rs2894536 and rs10972486) was associated with decreased HRs for hypertension development (HR = 0.762, 95% CI 0.659-0.882 and HR = 0.759, 95% CI 0.656-0.878). Our study demonstrated that genetically determined hypoalbuminemia is a significant predictor of incipient hypertension.

The Effects of Preoperative Fasting on Patients Undergoing Thoracic Surgery

PURPOSE

The purpose of this study was to determine the effects of fasting before surgery on patients undergoing thoracic surgery.

DESIGN

This descriptive cross-sectional study was conducted from January 1 to June 30, 2017.

METHODS

The study was carried out with 85 patients who underwent thoracotomy, mediastinoscopy, or rib resection in the thoracic surgery department of a university hospital. All patients started fasting midnight before day of surgery. Data were collected using a questionnaire, Visual Analog Patient Satisfaction Scale, and preoperative laboratory findings form.

FINDINGS

The mean fasting hours of solids and clear fluids were 8 and 16, respectively, and the mean duration of preoperative fasting (POF) was 10.16 (SD = 1.67), total fasting time average was 28.09 (SD = 7.11). Total protein and albumin levels decreased, and glucose level increased after surgery. The difference between total protein, albumin, and glucose levels preoperatively and postoperatively was significant (P < .05). The difference between patient satisfaction and thirst was found to be statistically significant (P < .05). A positive correlation was found between POF and thirst (r = 0.450; P = .000), hunger (r = 0.402; P = .000), total protein (r = 0.508; P = .000), albumin (r = 0.537; P = .000), and glucose levels (r = 0.371; P = .000).

CONCLUSIONS

POF had an adverse effect on thirst, hunger, and total protein as well as albumin and glucose levels.

Integration of molecular profiles in a longitudinal wellness profiling cohort

An important aspect of precision medicine is to probe the stability in molecular profiles among healthy individuals over time. Here, we sample a longitudinal wellness cohort with 100 healthy individuals and analyze blood molecular profiles including proteomics, transcriptomics, lipidomics, metabolomics, autoantibodies and immune cell profiling, complemented with gut microbiota composition and routine clinical chemistry. Overall, our results show high variation between individuals across different molecular readouts, while the intra-individual baseline variation is low. The analyses show that each individual has a unique and stable plasma protein profile throughout the study period and that many individuals also show distinct profiles with regards to the other omics datasets, with strong underlying connections between the blood proteome and the clinical chemistry parameters. In conclusion, the results support an individual-based definition of health and show that comprehensive omics profiling in a longitudinal manner is a path forward for precision medicine.

An important aspect of precision medicine is to probe the stability in molecular profiles among healthy individuals over time. Here, the authors sample a longitudinal wellness cohort and analyse blood molecular profiles as well as gut microbiota composition.

Increased age and male sex are independently associated with higher frequency of blood-cerebrospinal fluid barrier dysfunction using the albumin quotient

Background

The cerebrospinal fluid (CSF)/serum quotient of albumin (QAlb) is the most used biomarker for the evaluation of blood–cerebrospinal fluid barrier (B-CSF-B) permeability. For years QAlb was considered only as an age-related parameter but recently it has also been associated to sex. The aim of the present study was to explore the impact of sex in the determination of B-CSF-B dysfunction.

Methods

The analysis was retrospectively conducted on subjects consecutively admitted to the neurological ward. CSF and serum albumin levels were measured by immunonephelometry and pathological QAlb thresholds were considered: 6.5 under 40 years, 8.0 in the age 40–60 and 9.0 over 60 years.

Results

1209 subjects were included in the study. 718 females and 491 males (age: 15–88 years): 24.6% of patients had a diagnosis of multiple sclerosis, 23.2% suffered from other inflammatory neurological diseases, 24.6% were affected by non-inflammatory neurological diseases, and for 27.6% of patients the final neurological diagnosis could not be traced. Dysfunctional B-CSF-B was detected more frequently (44 vs. 20.1%, p < 0.0001) and median QAlb value were higher (7.18 vs. 4.87, p < 0.0001) in males than in females in the overall study population and in all disease subgroups. QAlb and age were positively correlated both in female (p < 0.0001) and male (p < 0.0001) patients, however the slopes of the two regression lines were not significantly different (p = 0.7149), while the difference between the elevations was extremely significant (p < 0.0001) with a gap of 2.2 units between the two sexes. Finally, in a multivariable linear regression analysis increased age and male sex were independently associated with higher QAlb in the overall study population (both p < 0.001) and after stratification by age and disease group.

Conclusions

Accordingly, identification and validation of sex-targeted QAlb thresholds should be considered as a novel tool in an effort to achieve more precision in the medical approach.

Comparing Ethnicity-Specific Reference Intervals for Clinical Laboratory Tests from EHR Data

BACKGROUND

The results of clinical laboratory tests are an essential component of medical decision-making. To guide interpretation, test results are returned with reference intervals defined by the range in which the central 95% of values occur in healthy individuals. Clinical laboratories often set their own reference intervals to accommodate variation in local population and instrumentation. For some tests, reference intervals change as a function of sex, age, and self-identified race and ethnicity.

METHODS

In this work, we develop a novel approach, which leverages electronic health record data, to identify healthy individuals and tests for differences in laboratory test values between populations.

RESULTS

We found that the distributions of >50% of laboratory tests with currently fixed reference intervals differ among self-identified racial and ethnic groups (SIREs) in healthy individuals.

CONCLUSIONS

Our results confirm the known SIRE-specific differences in creatinine and suggest that more research needs to be done to determine the clinical implications of using one-size-fits-all reference intervals for other tests with SIRE-specific distributions.

Mechanisms and Regulation of Intestinal Phosphate Absorption

States of hypo- and hyperphosphatemia have deleterious consequences including rickets/osteomalacia and renal/cardiovascular disease, respectively. Therefore, the maintenance of appropriate plasma levels of phosphate is an essential requirement for health. This control is executed by the collaborative action of intestine and kidney whose capacities to (re)absorb phosphate are regulated by a number of hormonal and metabolic factors, among them parathyroid hormone, fibroblast growth factor 23, 1,25(OH)₂ vitamin D₃ , and dietary phosphate. The molecular mechanisms responsible for the transepithelial transport of phosphate across enterocytes are only partially understood. Indeed, whereas renal reabsorption entirely relies on well-characterized active transport mechanisms of phosphate across the renal proximal epithelia, intestinal absorption proceeds via active and passive mechanisms, with the molecular identity of the passive component still unknown. The active absorption of phosphate depends mostly on the activity and expression of the sodium-dependent phosphate cotransporter NaPi-IIb (SLC34A2), which is highly regulated by many of the factors, mentioned earlier. Physiologically, the contribution of NaPi-IIb to the maintenance of phosphate balance appears to be mostly relevant during periods of low phosphate availability. Therefore, its role in individuals living in industrialized societies with high phosphate intake is probably less relevant. Importantly, small increases in plasma phosphate, even within normal range, associate with higher risk of cardiovascular disease. Therefore, therapeutic approaches to treat hyperphosphatemia, including dietary phosphate restriction and phosphate binders, aim at reducing intestinal absorption. Here we review the current state of research in the field. © 2017 American Physiological Society. Compr Physiol 8:1065-1090, 2018.

Longitudinal Examination of Links Between Risk Factors for the Metabolic Syndrome and Both Age and Fasting Glucose Levels in Nondiabetic Subjects

BACKGROUND

Previous evaluations in nondiabetic subjects revealed statistically significant correlations between fasting blood glucose (FBG) levels used as an estimate of insulin resistance and many components constituting the metabolic syndrome. Similar significant correlations were not found employing chronological age as the independent variable in the same nondiabetic individuals.

OBJECTIVE

The major purpose here was to replicate as well as corroborate the previous cross-sectional observations, emphasizing results obtained from data collected longitudinally.

METHODS

Material was assessed from 99 nondiabetic volunteers who had undergone 2 separate baseline measurements carried out over a minimum of 5 and up to a maximum of 20 years.

RESULTS

Findings from the starting baseline measurements mimicked many observations perceived in the earlier published cross-sectional material. The following correlations with elements constituting the metabolic syndrome using FBG as an independent variable were once more statistically significantly positive: scale weight, fat mass, circulating levels of triglycerides and high-sensitivity C-reactive protein (hsCRP). High-density lipoprotein (HDL) cholesterol was once again appropriately significant in a negative direction. In contrast, the same correlations were generally nonsignificant when age replaced FBG as the independent variable. Examining the 2 data sets over the 5-20-year intervals, FBG increased statistically significantly over time. However, the average increase clinically was relatively minor: -92.1 mg/dL ± 1.1 (SEM) vs 95.1 mg/dL ± 1.1 (SEM), p < 0.007. When the actual changes (delta) in the dependent parameters were correlated with the individual passages of time (intervals in years), only downward changes in aspartate aminotransferase (AST) levels were statistically significant. Fat-free mass showed a trend downward, whereas fat mass, trunk fat, and triglycerides merely demonstrated trends upward.

CONCLUSION

Current findings gathered over years are consistent with the original hypothesis that maintaining relatively low, stable circulating glucose levels during aging retards the development and intensity of many common manifestations of the metabolic syndrome.

Age and sex variation in serum albumin concentration: an observational study

BACKGROUND

In the UK, a common reference interval for serum albumin is widely used irrespective of age or sex. Implicit in this is that laboratories produce analytically similar results. This paper challenges the validity of this approach.

METHODS

A three-week collection of results sent to all primary care centres in England has been analysed by age, sex and laboratory. In all, 1,079,193 serum albumin reports were included in this analysis.

RESULTS

The mean population serum albumin concentration increases to peak at around age 20 years and then decreases with increasing age. Values in females decrease more rapidly but become close to male values at 60 years. The variation between laboratories was large and potentially clinically significant.

CONCLUSIONS

Reference intervals for serum albumin should be stratified by age and sex. Until there is greater methodological standardization, laboratories should determine their own reference intervals and not accept a single consensus reference interval.

Proteomic differences between male and female anterior cruciate ligament and patellar tendon

The risk of anterior cruciate ligament (ACL) injury and re-injury is greater for women than men. Among other factors, compositional differences may play a role in this differential risk. Patellar tendon (PT) autografts are commonly used during reconstruction. The aim of the study was to compare protein expression in male and female ACL and PT. We hypothesized that there would be differences in key structural components between PT and ACL, and that components of the proteome critical for response to mechanical loading and response to injury would demonstrate significant differences between male and female. Two-dimensional liquid chromatography-tandem mass spectrometry and a label-free quantitative approach was used to identify proteomic differences between male and female PT and ACL. ACL contained less type I and more type III collagen than PT. There were tissue-specific differences in expression of proteoglycans, and ACL was enriched in elastin, tenascin C and X, cartilage oligomeric matrix protein, thrombospondin 4 and periostin. Between male and female donors, alcohol dehydrogenase 1B and complement component 9 were enriched in female compared to male. Myocilin was the major protein enriched in males compared to females. Important compositional differences between PT and ACL were identified, and we identified differences in pathways related to extracellular matrix regulation, complement, apoptosis, metabolism of advanced glycation end-products and response to mechanical loading between males and females. Identification of proteomic differences between male and female PT and ACL has identified novel pathways which may lead to improved understanding of differential ACL injury and re-injury risk between males and females.

Nutritional status of patients on maintenance hemodialysis in urban sub-Saharan Africa: evidence from Cameroon

BACKGROUND

Malnutrition is an important predictive factor for morbidity and mortality in patients on maintenance dialysis. The evidence on the magnitude of the problem in sub-Saharan Africa is scanty. We assessed the nutritional status of patients on maintenance hemodialysis in the renal unit of the Douala General Hospital (Cameroon).

METHODS

Patients on maintenance hemodialysis for ≥3 months were enrolled between March and June 2012. Nutritional status was assessed via dietary recalls, anthropometric, and biochemical measurements including body mass index (BMI), triceps skinfold thickness, mid-arm circumference, mid-arm muscle circumference (MAMC), serum albumin, C-reactive protein (CRP) and hemoglobin, calcium, phosphorus, and vitamin D.

RESULTS

A total of 113 patients (75 men) were included. They were aged 49.4 years, and had been on dialysis for a median of 25 months. The mean BMI, MAMC and serum albumin was 22.4 kg/m(2), 23.7 cm and 42.4 g/l respectively. We observed that 28.3 % of patients were underweight (BMI ≤20 kg/m(2)), 23.9 % had muscle wasting (MAMC < adequacy to 50th percentile), and 31.6 % had low serum albumin (≤40 g/dl), while 21 % of patients had a combination of the three abnormalities. Prevalence rates for other indicators of under-nutrition were 26.3 % (low plasma cholesterol), 28 % (positive CRP) and 82.7 % (anemia). Female gender, younger age, less meals/day and frequent vegetable intake were associated with malnutrition risk.

CONCLUSIONS

Patients on maintenance hemodialysis in this setting have rates of malnutrition similar to those reported elsewhere. However, the high prevalence of malnutrition among women and young patients deserves further consideration.

Reference Ranges for Serum Uric Acid among Healthy Assamese People

This study was designed to establish reference ranges for serum uric acid among healthy adult Assamese population. Samples from 1470 aged 35-86 years were used to establish age and sex related reference range by the centile method (central 95 percentile) for serum uric acid level. There were 51% (n = 754) males and 49% (n = 716) females; 75.9% (n = 1115) of them were from urban area and the rest 24.1% (n = 355) were from the rural area. Majority of the population were nonvegetarian (98.6%, n = 1450) and only 1.4% (n = 20) were vegetarian. The mean age, weight, height, and uric acid of the studied group were 53.6 ± 11.3 years, 62.6 ± 10.5 kg, 160 ± 9.4 cm, and 5.5 ± 1.4 mg/dL, respectively. There is a statistically significant difference in the mean value of the abovementioned parameters between male and female. The observed reference range of uric acid in the population is 2.6-8.2 mg/dL which is wider than the current reference range used in the laboratory. Except gender (P < 0.0001), we did not find any significant relation of uric acid with other selected factors.

Metabolism, temperature, and ventilation

In mammals and birds, all oxygen used (VO2) must pass through the lungs; hence, some degree of coupling between VO2 and pulmonary ventilation (VE) is highly predictable. Nevertheless, VE is also involved with CO2 elimination, a task that is often in conflict with the convection of O2. In hot or cold conditions, the relationship between VE and VO2 includes the participation of the respiratory apparatus to the control of body temperature and water balance. Some compromise among these tasks is achieved through changes in breathing pattern, uncoupling changes in alveolar ventilation from VE. This article examines primarily the relationship between VE and VO2 under thermal stimuli. In the process, it considers how the relationship is influenced by hypoxia, hypercapnia or changes in metabolic level. The shuffling of tasks in emergency situations illustrates that the constraints on VE-VO2 for the protection of blood gases have ample room for flexibility. However, when other priorities do not interfere with the primary goal of gas exchange, VE follows metabolic rate quite closely. The fact that arterial CO2 remains stable when metabolism is changed by the most diverse circumstances (moderate exercise, cold, cold and exercise combined, variations in body size, caloric intake, age, time of the day, hormones, drugs, etc.) makes it unlikely that VE and metabolism are controlled in parallel by the condition responsible for the metabolic change. Rather, some observations support the view that the gaseous component of metabolic rate, probably CO2, may provide the link between the metabolic level and VE.

Dehydration in hospital-admitted stroke patients: detection, frequency, and association

BACKGROUND AND PURPOSE

We aimed to determine the frequency of dehydration, risk factors, and associations with outcomes at hospital discharge after stroke.

METHODS

We linked clinical data from stroke patients in 2 prospective hospital registers with routine blood urea and creatinine results. Dehydration was defined by a blood urea-to-creatinine ratio >80.

RESULTS

Of 2591 patients registered, 1606 (62%) were dehydrated at some point during their admission. Independent risk factors for dehydration included older age, female gender, total anterior circulation syndrome, and prescribed diuretics (all P<0.001). Patients with dehydration were significantly more likely be dead or dependent at hospital discharge than those without (χ(2)=170.5; degrees of freedom=2; P<0.0001).

CONCLUSIONS

Dehydration is common and associated with poor outcomes. Further work is required to establish if these associations are causal and if preventing or treating dehydration improves outcomes.

Daily consumption of an aqueous green tea extract supplement does not impair liver function or alter cardiovascular disease risk biomarkers in healthy men

Regular consumption of green tea polyphenols (GTP) is thought to reduce the risk of cardiovascular disease (CVD) but has also been associated with liver toxicity. The present trial aimed to assess the safety and potential CVD health beneficial effects of daily GTP consumption. We conducted a placebo-controlled parallel study to evaluate the chronic effects of GTP on liver function and CVD risk biomarkers in healthy men. Volunteers (treatment: n = 17, BMI 26.7 +/- 3.3 kg/m(2), age 41 +/- 9 y; placebo, n = 16, BMI 25.4 +/- 3.3 kg/m(2), age 40 +/- 10 y) consumed for 3 wk 6 capsules per day (2 before each principal meal) containing green tea extracts (equivalent to 714 mg/d GTP) or placebo. At the beginning and end of the intervention period, we collected blood samples from fasting subjects and measured vascular tone using Laser Doppler Iontophoresis. Biomarkers of liver function and CVD risk (including blood pressure, plasma lipids, and asymmetric dimethylarginine) were unaffected by GTP consumption. After treatment, the ratio of total:HDL cholesterol was significantly reduced in participants taking GTP capsules compared with baseline. Endothelial-dependent and -independent vascular reactivity did not significantly differ between treatments. In conclusion, the present data suggests that the daily consumption of high doses of GTP by healthy men for 3 wk is safe but without effects on CVD risk biomarkers other than the total:HDL cholesterol ratio.

Trends and outcomes associated with serum albumin concentration among incident dialysis patients in the United States

OBJECTIVE AND METHODS

Serum albumin concentrations are associated with mortality, and respond to nutritional and inflammatory states. To explore whether changing demographics and practice patterns in dialysis have influenced serum albumin concentrations, we analyzed trends in serum albumin among incident patients on dialysis from 1995 through 2004.

RESULTS

Mean serum albumin concentrations declined significantly over time, even after accounting for changes in age, diabetes, body size, and other factors. Although laboratory assays were not uniform within or across years, serum albumin declined over time, regardless of the reported laboratory lower limit of normal. Moreover, serum albumin retained its potent association with mortality over time. Lower serum albumin was especially hazardous among younger patients and blacks, and was less hazardous among persons with diabetes as a primary cause of kidney disease.

CONCLUSIONS

Despite higher body weights and the initiation of dialysis earlier in the course of progressive chronic kidney disease, hypoalbuminemia remains common and hazardous to persons starting dialysis.

Laboratory parameters in centenarians of Italian ancestry

Studies aimed at collecting reference parameters for haematochemical analysis in the elderly are scarce and for the oldest old subjects even more rare. In order to establish the reference values for the most common laboratory text in long living individuals, we measured haematochemical parameters in >100 years old subjects and in aged subjects as control. Six hundred and two centenarians accepted to be enrolled in the study. A case history containing the complete anamnesis, clinical examinations, evaluation of the clinical cognitive and functional tests, was prepared for each centenarian. Blood samples from 120>100 years old subjects free of chronic or acute Illness (i.e. Alzheimer's disease, metabolic diseases, cardiovascular disease, stroke, neoplastic and infectious diseases) were analysed. A population of 381 healthy old subjects (age range 65-85 years old), recruited in the same geographic areas and with the same clinical characteristic of the health centenarians, was utilized as control. Significant differences were observed for blood glucose, ALT, cholesterol and platelet levels, reduced in centenarians respect to the old subjects, whereas blood urea nitrogen levels were found significantly increased in centenarians. In conclusion, reference values of the healthy adults can generally been utilized also for the healthy oldest old group, with the notable exception of the above mentioned laboratory parameters that appear to be modified in long living subjects.

Evaluation of Selected Laboratory Components of a Comprehensive Periodic Health Evaluation for Veterans With Spinal Cord Injury and Disorders

OBJECTIVE

To evaluate selected laboratory components of a comprehensive periodic health evaluation program for patients with spinal cord injury and disorders (SCI/D).

DESIGN

A retrospective study.

SETTING

A Department of Veterans Affairs spinal cord injury center.

PARTICIPANTS

Community-dwelling male veterans with SCI/D (N=350).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Proportion of laboratory tests that resulted in new diagnoses (diagnostic yield) and proportion of laboratory tests that resulted in changes in management (therapeutic yield).

RESULTS

Although abnormality rates for many routine laboratory tests were high (up to 31.5%), diagnostic and therapeutic yields were low (<1.5%), with the exception of glucose (therapeutic yield, 3.4%) and lipid tests (up to a 4.1% diagnostic and 15.2% therapeutic yield).

CONCLUSIONS

Our data revealed that diagnostic and therapeutic yields for many laboratory components of the annual PHE program for veterans with SCI/D were low, consistent with findings in the general ambulatory population. Further data collection, particularly prospective longitudinal data, may help optimize the selection and frequency of laboratory tests performed as part of this program.

Population Pharmacokinetics of Tacrolimus in Whole Blood and Plasma in Asian Liver Transplant Patients

OBJECTIVES

The objectives of this study were to develop population pharmacokinetic models of tacrolimus in an Asian population with whole blood and plasma drug concentration data, to compare the variability of the pharmacokinetic parameters in these two matrices and to search for the main patient characteristics that explain the variability in pharmacokinetic parameters.

STUDY DESIGN

Prospective pharmacokinetic assessment followed by model fitting.

PATIENTS

Whole blood samples from 31 liver transplant patients in a local hospital receiving oral tacrolimus as part of their immunosuppressive therapy were assessed. Plasma samples from 29 of the 31 patients were also evaluated. Concentrations of tacrolimus in whole blood and plasma were determined by an electrospray high-performance liquid chromatography with tandem mass spectrometry. Two hundred and thirteen whole blood and 157 plasma tacrolimus concentrations were used for building two nonlinear mixed-effects population models to describe the disposition of tacrolimus in whole blood and plasma, respectively. Covariates that were investigated included demographic characteristics, biological markers of liver and renal functions, corticosteroid dose and haematological parameter.

RESULTS

A one-compartment model was used to describe the whole blood and plasma concentration-time data of tacrolimus after oral administration. For the whole blood population model, the population estimates of the first-order absorption rate constant (k(a)), apparent clearance based on whole blood concentration after oral administration (CL(B)/F) and apparent volume of distribution based on whole blood concentrations after oral administration (V(d,B)/F) were 2.08h(-1), 14.1 L/h and 217L, respectively. The coefficient of variations (CVs) of interpatient variabilities in CL(B)/F and V(d,B)/F were 65.7% and 63.8%, respectively. Bodyweight, liver and renal function influenced CL(B)/F, while height and haematocrit influenced V(d,B)/F. The residual (unexplained) variability was 34.8%. For the plasma population model, the population estimates of the k(a), apparent clearance based on plasma concentrations after oral administration (CL(P)/F) and apparent volume of distribution based on plasma concentrations after oral administration (V(d,P)/F) were 5.21h(-1), 537 L/h and 563L, respectively. The CVs of interpatient variabilities in CL(P)/F and V(d,P)/F were 96.0% and 105.4%, respectively. Bodyweight was found to influence CL(P)/F, while the erythrocyte-to-plasma concentration ratio influenced V(d,P)/F. The residual (unexplained) variability was 49.8% at the mean plasma concentration of 1.1 ng/mL.

CONCLUSIONS

Whole blood and plasma population pharmacokinetic models of tacrolimus in Asian adult and paediatric liver transplant patients were developed using prospective data in a clinical setting. This has identified and quantified sources of interindividual variability in CL(B)/F, V(d,B)/F, CL(P)/F and V(d,P)/F of tacrolimus in Asian liver transplant patients. Information derived from the whole blood population model may subsequently be used by clinicians for dosage individualisation through Bayesian forecasting.

Serum alkaline phosphatase activity is regulated by a chromosomal region containing the alkaline phosphatase 2 gene (Akp2) in C57BL/6J and DBA/2J mice

Quantitative trait locus (QTL) analyses were conducted to identify chromosomal regions that contribute to variability in serum alkaline phosphatase (AP) enzyme activity in mice derived from the C57BL/6J (B6) and DBA/2J (D2) inbred strains. Serum AP was measured in 400 B6D2 F2 mice at 5 mo and 400 B6D2 F2 mice at 15 mo of age that were genotyped at 96 microsatellite markers, and in 19 BXD recombinant inbred (RI) strains at 5 mo of age. A QTL on the distal end of chromosome 4 was present in all sex- and age-specific analyses with a peak logarithm of odds (LOD) score of 20.36 at 58.51 cM. The Akp2 gene, which encodes the major serum AP isozyme, falls within this QTL region at 70.2 cM where the LOD score reached 13.2 (LOD significance level set at 4.3). Serum AP activity was directly related to the number of D2 alleles of a single nucleotide polymorphism in the 5'-flanking region of the Akp2 gene, although no strain-related differences in hepatic expression of Akp2 RNA were found. A variety of sequence polymorphisms in this chromosomal region could be responsible for the differences in serum AP activity; the Akp2 gene, however, with several known amino acid substitutions between protein sequences of the B6 and D2 strains, is a leading candidate.

Sampling Airway Surface Liquid: Non-Volatilesin the Exhaled Breath Condensate

Exhaled breath condensate (EBC) samples contain molecules that have no appreciable vapor pressure; such molecules likely derive from droplets of airway fluid. We analyzed EBC gathered from a total of 62 healthy volunteers in order to quantify the volume of airway liquid that was the source of the non-volatiles; saliva was analyzed as a reference secretion. EBC urea averaged 0.52 +/- 0.12 micromol/L (n = 18), an 8,600-fold dilution from predicted blood urea nitrogen levels. Protein averaged 2.3 +/- 0.3 microg/ml (n = 31), three orders of magnitude less than in saliva (1.4 +/- 0.1 mg/ml, n = 15). EBC ammonia was 6.6 +/- 0.6 mmol/L (1/15 that of saliva) and EBC ammonium ion was 0.90 +/- 0.19 micromol/L, concentrations that are incompatible with an 8,600-fold dilution from a biological source. Thus, urea-derived dilution factors may be used to interpret EBC non-volatile molecules, but not EBC volatiles.

Cross-sectional relationship between dietary protein and energy intake, nutritional status, functional status, and comorbidity in older versus younger hemodialysis patients

OBJECTIVE

To evaluate the dietary energy intakes (DEI) and dietary protein intakes (DPI) of older (> or = 65 years), middle-aged (50 to 64 years), and younger (< 50 years) maintenance hemodialysis patients enrolled in the Hemodialysis (HEMO) Study, and to describe the relationship between age, nutritional status, functional status, and comorbidity.

DESIGN

A cross-sectional analysis of the first 1,397 participants in baseline (before randomization) was performed.

MAIN OUTCOME MEASURES

DEI and DPI, serum albumin, creatinine, total cholesterol, normalized protein catabolic rate (nPCR), equilibrated nPCR (enPCR), functional status, and comorbidities.

RESULTS

Mean DEI, DPI, serum albumin, creatinine, nPCR, and enPCR were significantly lower in the older compared with the younger patients, despite similar doses of dialysis as measured by equilibrated Kt/V. Mean DEI, DPI, nPCR, and enPCR were not significantly different between the middle-aged and older patients, whereas albumin and creatinine were significantly lower in the older patients. Mean dry weight and percent of standard body weight in the younger and older patients were similar. In all groups, mean DEI was lower than both the HEMO study's standard of care (SOC) and the Kidney Disease Outcomes Quality Initiative (K/DOQI) nutrition recommendations, whereas mean DPI was lower than the SOC and K/DOQI recommendations only in the middle-aged and older patients. Middle-aged and older patients had higher cholesterol, lower functional status, and more comorbidities than the younger patients.

CONCLUSION

Middle-aged and older maintenance dialysis patients may be at greater risk for developing protein-energy malnutrition than their younger counterparts. Inadequate DEI and DPI reported in middle-aged and older patients were associated with lower levels of biomarkers of nutritional status, lower functional status, and higher comorbidities than in the younger patients.

Hormone replacement therapy causes a respiratory alkalosis in normal postmenopausal women

Menopause is associated with an increase in venous bicarbonate concentrations that is reversible with hormone replacement therapy (HRT). However, the mechanism underlying this effect is not known. To address this question, we studied the changes in acid-base indexes in the arterialized venous blood of normal postmenopausal women commencing conjugated equine estrogen (0.625 mg/day), medroxyprogesterone acetate (MPA; 5 mg/day), their combination, or placebo, in a double blind randomized controlled study over 3 months. Serum bicarbonate concentrations decreased significantly in the groups receiving either MPA or estrogen plus MPA (P = 0.008). This trend was apparent as early as 2 days and reached 2.7 and 2.3 mmol/L in the respective groups by 3 months. Similar changes were seen with partial pressure of carbon dioxide (P = 0.04); a change of -0.7 kPa occurred in the estrogen plus MPA group at 3 months. There were no changes in bicarbonate concentrations or partial pressure of carbon dioxide in those receiving estrogen alone or placebo. Accompanying changes in blood pH were apparent in the estrogen plus MPA group, where there was an upward trend at 1 week (P = 0.056) and a significant change from baseline (+0.013) at 3 months (P = 0.03). In the whole group, the changes in pH were inversely correlated with those in urinary excretion of hydroxyproline (r = -0.44; P = 0.01). We conclude that HRT using conjugated estrogens and MPA produces small, but sustained, changes in acid-base status. These may contribute to the effects of HRT and menopause on many tissues and disease processes, including the development of osteoporosis.

Factors predicting malnutrition in hemodialysis patients: a cross-sectional study

Signs of protein-energy malnutrition are common in maintenance hemodialysis (HD) patients and are associated with increased morbidity and mortality. To evaluate the nutritional status and relationship between various parameters used for assessing malnutrition, we performed a cross-sectional study in 128 unselected patients treated with hemodialysis (HD) thrice weekly for at least two weeks. Global nutritional status was evaluated by the subjective global nutritional assessment (SGNA). Body weight, skinfold thicknesses converted into % body fat mass (BFM), mid-arm muscle circumference, hand-grip strength and several laboratory values, including serum albumin (SA1b), plasma insulin-like growth factor I (p-IGF-I), serum C-reactive protein (SCRP) and plasma free amino acids, were recorded. Dose of dialysis and protein equivalence of nitrogen appearance (nPNA) were evaluated by urea kinetic modeling. The patients were subdivided into three groups based on SGNA: group I, normal nutritional status (36%); group II, mild malnutrition (51%); and group III, moderate or (in 2 cases) severe malnutrition (13%). Clinical factors associated with malnutrition were: high age, presence of cardiovascular disease and diabetes mellitus. nPNA and Kt/V(urea) were similar in the three groups. However, when normalized to desirable body wt, both were lower in groups II and III than in group I. Anthropometric factors associated with malnutrition were low body wt, skinfold thickness, mid-arm muscle circumference (MAMC), and handgrip strength. Biochemical factors associated with malnutrition were low serum levels of albumin and creatinine and low plasma levels of insulin-like growth factor 1 (IGF-1) and branched-chain amino acids (isoleucine, leucine and valine). The serum albumin (SAlb) level was not only a predictor of nutritional status, but was independently influenced by age, sex and SCRP. Plasma IGF-1 levels also reflected the presence and severity of malnutrition and appeared to be more closely associated than SAlb with anthropometric and biochemical indices of somatic protein mass. Elevated SCRP (> 20 mg/liter), which mainly reflected the presence of infection/inflammation and was associated with hypoalbuminemia, was more common in malnourished patients than in patients with normal nutritional status, and also more common in elderly than in younger patients. Plasma amino acid levels, with the possible exception of the branched-chain amino acids (isoleucine, leucine, valine), seem to be poor predictors of nutritional status in hemodialysis patients.

Reference intervals for the glomerular filtration rate and cell-proliferation markers: serum cystatin C and serum beta 2-microglobulin/cystatin C-ratio

Recent studies have indicated that serum and plasma cystatin C are better markers for glomerular filtration rate (GFR) than serum creatinine, ubiquitously used for this purpose. To fully exploit the value of serum and plasma cystatin C as GFR markers, reliable age and sex-correlated reference intervals are required. The present study comprised cystatin C determinations in plasma and sera from 259 individuals from a well-defined area in the southernmost part of Sweden. From demographic lists two men and two women were randomly selected from each one-year birth cohort above 20 years of age. No sex differences were found for plasma and serum cystatin C, whereas an increase in the cystatin C levels with age was noted, corresponding to the known age-related decrease in GFR. The following reference intervals are recommended for practical clinical use: S-Cystatin C (both sexes): 20-50 years, 0.70-1.21 mg l-1 and 50+ years, 0.84-1.55 mg l-1. The same samples were also used for determination of beta 2-microglobulin levels in order to calculate reference intervals for the beta 2-microglobulin/cystatin C-ratio, which is a more distinct marker for cell proliferation, particularly lymphoproliferation, than is the serum level of beta 2-microglobulin alone, since the ratio should be virtually uninfluenced by GFR. The beta 2-microglobulin/cystatin C-ratios were uninfluenced by sex and age and 1.45-2.43 is recommended as the serum reference interval for practical clinical use. Serum creatinine was determined in the same samples and the creatinine level was found to be strongly influenced by sex and weakly by age.

Correlation of reproductive aging with function in selected organ systems

OBJECTIVE

To compare day 3 FSH levels with biomarkers of aging in other organ systems in healthy, older, reproductive age women.

DESIGN

Cross-sectional pilot study.

SETTING

Healthy volunteers in an academic, tertiary care center.

PATIENT(S)

Healthy, regularly cycling women aged 40 to 45 years divided into two groups: those with normal day 3 FSH levels and those with elevated day 3 FSH levels.

INTERVENTION(S)

Blood and urine collection with blood pressure measurement, pulmonary function testing, bone densitometry, and skin biopsy.

MAIN OUTCOME MEASURE(S)

Comparison between groups for serum creatinine, albumin, glucose, hematocrit, DHEAS, fasting insulin, low-density lipoprotein cholesterol, and triglyceride levels; creatinine clearance (CrCl); forced expiratory volume in 1 second; forced vital capacity; bone density at the wrist, hip, and lumbar spine; and mean dermal thickness.

RESULT(S)

Hematocrit and CrCl values were significantly lower in the group with high FSH levels. Creatinine clearance also was significantly negatively correlated with FSH level. After Bonferroni adjustment for multiple testing, all measures were no longer different at the P < or = 0.05 level.

CONCLUSION(S)

Aging of the hypothalamic-pituitary-ovarian axis may parallel aging in other organ systems. Further longitudinal analyses are necessary to ascertain whether these measures will predict reproductive reserve before irreversible dysfunction occurs.

Are elevated aminotransferases and decreased bilirubin additional characteristics of the metabolic syndrome?

Abnormal liver tests, as well as morphological changes in the liver, are frequent among obese patients. Other frequent disturbances are visceral fat accumulation, insulin resistance, non-insulin-dependent diabetes mellitus (NIDDM), hypertriglyceridemia, and hypertension; these are set of aberrations known as the metabolic syndrome. In order to investigate a possible relationship between the metabolic syndrome and impaired liver status we examined associations between liver tests, metabolic variables (insulin, glucose, and triglycerids), body composition and nutrition in 1,083 men (BMI 28.8-63.8 kg/m2) and 1,367 women (BMI 26.7-68.0 kg/m2) in the ongoing intervention study of Swedish Obese Subjects (SOS). Standard biochemical techniques were used to assess liver status and metabolic variables. Lean body mass (LBM) and masses of visceral and subcutaneous adipose tissue (AT) were estimated by means of computed tomography (CT) calibrated anthropometric equations. In both genders aspartate aminotransferase and alanine aminotransferase were, or tended to be, positively correlated to fasting serum insulin, visceral AT (women), and alcohol intake. In women, the aminotransferases were also correlated with fasting blood glucose. In both genders alkaline phosphatase was, or tended to be, positively associated with visceral AT, insulin (women), and glucose. Bilirubin was negatively correlated to insulin and visceral AT in men and women. Additional multivariate analyses indicated that alcohol had less explanatory power than serum insulin for the examined liver tests, especially among women. These results suggest that pathological liver tests in the obese may represent an expression of the metabolic syndrome.

Hematological and biochemical laboratory values in older Cardiovascular Health Study participants

OBJECTIVE

To define reference hematologic and biochemical lab values in older individuals.

DESIGN

Randomly selected, age- and gender-stratified participants.

SETTING

Visits by participants to four research clinics.

PATIENTS

A total of 5201 participants in the Cardiovascular Health Study, an observational study of older Medicare-eligible individuals living at home.

MEASUREMENT

Information about health status, previous illness, and medication use was obtained from participants and/or their MDs. This information was used to define a healthy subset of the population. Blood samples were obtained for Cholesterol, HDL and LDL cholesterol, fasting and 2-hour postload glucose and insulin, fibrinogen, factors VII and VIII, potassium, creatinine, albumin, uric acid, white blood count, hematocrit, hemoglobin, and platelet count.

RESULTS

Significant differences were found for age group and/or gender for all mean values. Many tests were significantly different from the generally accepted reference ranges used in clinical laboratories.

CONCLUSIONS

In some situations accepted laboratory norms for the general population can not be extrapolated to older adults. There are implications for both research and clinical practice.

The effects of menopause and age on calcitropic hormones: a cross-sectional study of 655 healthy women aged 35 to 90

Although women lose 30% of their skeletal mass after the menopause, the mechanism of this loss is uncertain. Clearly estrogen deficiency is important but whether this works only through direct effects on the skeleton is uncertain. To examine these mechanisms further we have evaluated calcium-related metabolic factors in 655 healthy women. Fasting blood samples were collected from all subjects who were up to 35 years past the menopause, and fasting urine and 24-h urine samples were collected in 365 women who were up to 25 years past the menopause. In the first 15 years postmenopause, there was a rise in total plasma calcium due to a rise in albumin. Bone resorption (hydroxyproline creatinine ratio), bone formation (alkaline phosphatase), and the urine calcium creatinine ratio all rose at menopause and remained elevated for the next 25 years. There was a transient further rise in bone resorption for the 10 years following menopause. Neither PTH nor the free calcitriol index changed for the first 10 years following menopause. Ten years past the menopause, although total calcitriol rose, the free calcitriol index fell due to a rise in vitamin D binding protein. PTH began to rise at 15 years past menopause. GFR fell gradually over the 25 years following menopause. Thus following menopause there is an increase in bone turnover and increased urine calcium loss independent of any effect of PTH or calcitriol, suggesting a direct effect of estrogen deficiency on bone and kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Screening for presymptomatic disease

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The construction of biochemical reference ranges and the identification of possible adverse drug reactions in the elderly

In the assessment of adverse drug reactions (ADRs) it is important to establish what is a normal range of values for a given biochemical measurement. Furthermore, such ranges need to be specific to the study population, for example, the elderly. A mixture of Gaussian distributions has been used in the construction of the reference ranges with maximum likelihood used to obtain estimates of the unknown parameters. With this approach, well-defined reference ranges have been established. Brief details are given of the numbers of ADRs identified in the study population using these ranges.

A comparative study of atherosclerosis and osteopenia in elderly and young hemodialysis patients

The effects of aging on atherosclerosis and osteopenia in hemodialysis patients were investigated. Eighty patients on maintenance hemodialysis were subdivided according to age into old (greater than or equal to 65 years old, N = 40) and young (less than 65 years old, N = 40). Biochemical, radiologic, and biophysical studies were performed in each patient to assess the degree of atherosclerosis and osteopenia. Compared to age-matched controls, patients in the old group exhibited a significantly higher aortic pulse wave velocity (PWV), and old female patients had a significantly lower bone mineral content/bone width (BMC/W). Elderly patients also had a significantly higher aortic PWV and higher grade of aortic calcification as assessed radiologically; in contrast, the BMC/W was lower. Concerning sex differences, elderly male patients had the highest average grade of aortic calcification, the lowest serum Pi, [Ca] x [Pi], and immunoreactive parathyroid hormone concentrations, while elderly female patients had the lowest BMC/W and highest incidence of osteopenia. These observations suggest that elderly male hemodialysis patients are more prone to develop atherosclerosis and elderly female hemodialysis patients to develop advanced osteopenia.

Elderly people taking non-steroidal anti-inflammatory drugs are unlikely to have excess renal impairment

The importance of possible adverse effects on renal function of non-steroidal anti-inflammatory drugs has been widely discussed. Elderly people have been thought to be particularly at risk. We therefore studied simple indices of renal function and plasma potassium in 54 patients with a mean age of 85 years, 27 taking these drugs and 27 controls. Twenty five of our 54 patients were also taking diuretics. Non-steroidal anti-inflammatory drugs did not affect renal function or plasma potassium in these patients.

Blood laboratory parameters of carefully selected healthy elderly people

Hematological and biochemical parameters were measured in carefully selected healthy elderly (50 males and 50 females, aged 60-97 years) and young (10 males and 10 females, aged 18-23 years) populations. Most of the parameters measured did not show any age-related variations. It means that any deviation from the present normal ranges established for healthy young subjects should be considered as pathologic in the case of elderly, too. Some parameters showed age-specific changes and hence there is a possibility that their actual normal ranges might be extended towards the upper limit (globulin, IgG, IgA, CIC, C3, BUN, AP for females), or towards the lower limit (creatinine clearance, albumin). Verification of these modifications may indicate that a lot of unnecessary investigations in the case of elderly could be avoided.

Diurnal variations in serum biochemical and haematological measurements

Twenty five biochemical and haematological measurements were determined on nonfasting blood and serum samples collected between 9 am and 7 pm from a representative group of 7685 British middle-aged men. Most measurements showed significant diurnal variations, but only for bilirubin, phosphate, and triglyceride did time of day account for more than 5% of the between subject variance. Serum bilirubin concentrations showed a pronounced downward trend in the afternoon, the mean value after 6 pm being 30% lower than the mean value in the morning. Mean serum triglyceride and phosphate concentrations increased steadily through the day. Mean concentrations of potassium, haemoglobin, and haematocrit and red cell count were higher in the morning, while urea and creatinine concentrations and white cell count had higher means in the afternoon. Glucose showed a pattern consistent with short term response to meals. The effects of these diurnal trends on routine use of biochemical tests needs careful consideration, and a greater understanding of their biological mechanisms is required.

A randomized study on the effects of estrogen/gestagen or high dose oral calcium on trabecular bone remodeling in postmenopausal osteoporosis

Thirty-seven patients with postmenopausal crush fracture osteoporosis were randomized to oral cyclic estrogen/gestagen (n = 20) or oral calcium (2000 mg elemental calcium per day) (n = 17). Fourteen in each group completed 1 year of treatment. Iliac crest bone biopsies were obtained after intravital double labeling with tetracycline before and after treatment in 10 patients on estrogen/gestagen and 11 patients on calcium. In the estrogen/gestagen group the activation frequency in trabecular bone decreased from 0.52 + 0.11 (SEM) year-1 to 0.27 + 0.08 year-1 (p less than 0.01). No significant changes were found in resorption or formation periods. The osteoid surfaces and the mineralizing surfaces decreased (p less than 0.05), whereas the decrease in eroded surfaces was insignificant. Furthermore, no significant changes were observed in final resorption depth, wall thickness or bone balance per remodeling cycle. Serum alkaline phosphatase and renal hydroxyproline excretion decreased during treatment (p less than 0.002), whereas the lumbar bone mineral content (BMC) increased (p less than 0.01). In the calcium group the extent and thickness of osteoid surfaces decreased (p less than 0.05) without significant changes in activation frequency. Serum alkaline phosphatase and renal hydroxyproline excretion decreased during treatment (p less than 0.02). No significant changes were observed in lumbar BMC or the other histomorphometric parameters. The study supports that the positive effect of estrogen/gestagen on BMC can be explained by a reduction in the activation frequency of new remodeling cycles leading to a decreased remodeling space and an increase in mean bone age. There is no evidence of a positive balance per remodeling cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of dietary calcium deprivation on serum calcitriol levels in premenopausal and postmenopausal women

The effect of the postmenopausal state on serum calcitriol levels was studied in 13 normal premenopausal women and 10 normal postmenopausal women under basal conditions and during seven days of dietary calcium deprivation. Calcitriol levels and the free calcitriol index were lower in the postmenopausal women, and this difference persisted during calcium deprivation. One of the major actions of calcitriol is to increase gut calcium absorption. Relative calcitriol deficiency, despite retained renal synthetic reserve, would in part explain the increased dietary calcium requirement to maintain calcium balance in postmenopausal women.

Distribution-free estimation of age-related centiles

A method is described for calculating age-related centiles which makes no assumption about the nature of the distribution of the measurement at a fixed age.