Quantitative liver function in the elderly assessed by galactose elimination capacity, aminopyrine demethylation and caffeine clearance

Non-fermented and fermented milk intake in relation to risk of ischemic heart disease and to circulating cardiometabolic proteins in swedish women and men: Two prospective longitudinal cohort studies with 100,775 participants

BACKGROUND

The effect of milk on the risk of ischemic heart disease (IHD) and acute myocardial infarction (MI) is unclear. We aimed to examine the association between non-fermented and fermented milk consumption on these endpoints and investigate the relationship between milk intake and cardiometabolic-related proteins in plasma.

METHODS

Our study is based on two Swedish prospective cohort studies that included 59,998 women and 40,777 men without IHD or cancer at baseline who provided repeated measures of diet and lifestyle factors and plasma proteomics data in two subcohorts. Through registry linkage, 17,896 cases with IHD were documented during up to 33 years of follow-up, including 10,714 with MI. We used time-updated multivariable Cox regression analysis to examine non-fermented or fermented milk intake with time to IHD or MI. Using high-throughput multiplex immunoassays, 276 cardiometabolic plasma proteins were measured in two subcohorts. We applied multivariable-adjusted regression models using a discovery-replication design to examine protein associations with increasing consumption of non-fermented or fermented milk.

RESULTS

The results for non-fermented milk differed by sex (p-value for interaction = 0.01). In women, we found a pattern of successively greater risk of IHD and MI at non-fermented milk intake levels higher than 1.5 glasses/day. Compared with an intake of 0.5 glass/day (100 mL/day), non-fermented milk intake of 2 glasses/day in women conferred a multivariable-adjusted hazard ratio (HR) of 1.05 (95% CI 1.01-1.08) for IHD, an intake of 3 glasses/day an HR of 1.12 (95% CI 1.06-1.19), and an intake of 4 glasses/day an HR of 1.21 (95% CI 1.10-1.32). Findings were similar for whole, medium-fat, and low-fat milk. We did not detect higher risks of IHD with increasing milk intakes in men. Fermented milk intake was unrelated to the risk of IHD or MI in either sex. Increasing non-fermented milk intake in women was robustly associated with a higher concentration of plasma ACE2 and a lower concentration of FGF21.

CONCLUSIONS

We show a positive association between high amounts of non-fermented milk intake and IHD in women but not men. We suggest metabolic pathways related to ACE2 and FGF21 potentially underlie the association.

Lifetime Impact of Cow's Milk on Overactivation of mTORC1: From Fetal to Childhood Overgrowth, Acne, Diabetes, Cancers, and Neurodegeneration

The consumption of cow's milk is a part of the basic nutritional habits of Western industrialized countries. Recent epidemiological studies associate the intake of cow's milk with an increased risk of diseases, which are associated with overactivated mechanistic target of rapamycin complex 1 (mTORC1) signaling. This review presents current epidemiological and translational evidence linking milk consumption to the regulation of mTORC1, the master-switch for eukaryotic cell growth. Epidemiological studies confirm a correlation between cow's milk consumption and birthweight, body mass index, onset of menarche, linear growth during childhood, acne vulgaris, type 2 diabetes mellitus, prostate cancer, breast cancer, hepatocellular carcinoma, diffuse large B-cell lymphoma, neurodegenerative diseases, and all-cause mortality. Thus, long-term persistent consumption of cow's milk increases the risk of mTORC1-driven diseases of civilization. Milk is a highly conserved, lactation genome-controlled signaling system that functions as a maternal-neonatal relay for optimized species-specific activation of mTORC1, the nexus for regulation of eukaryotic cell growth, and control of autophagy. A deeper understanding of milk´s impact on mTORC1 signaling is of critical importance for the prevention of common diseases of civilization.

Synergistic Effects of Milk-Derived Exosomes and Galactose on α-Synuclein Pathology in Parkinson's Disease and Type 2 Diabetes Mellitus

Epidemiological studies associate milk consumption with an increased risk of Parkinson's disease (PD) and type 2 diabetes mellitus (T2D). PD is an α-synucleinopathy associated with mitochondrial dysfunction, oxidative stress, deficient lysosomal clearance of α-synuclein (α-syn) and aggregation of misfolded α-syn. In T2D, α-syn promotes co-aggregation with islet amyloid polypeptide in pancreatic β-cells. Prion-like vagal nerve-mediated propagation of exosomal α-syn from the gut to the brain and pancreatic islets apparently link both pathologies. Exosomes are critical transmitters of α-syn from cell to cell especially under conditions of compromised autophagy. This review provides translational evidence that milk exosomes (MEX) disturb α-syn homeostasis. MEX are taken up by intestinal epithelial cells and accumulate in the brain after oral administration to mice. The potential uptake of MEX miRNA-148a and miRNA-21 by enteroendocrine cells in the gut, dopaminergic neurons in substantia nigra and pancreatic β-cells may enhance miRNA-148a/DNMT1-dependent overexpression of α-syn and impair miRNA-148a/PPARGC1A- and miRNA-21/LAMP2A-dependent autophagy driving both diseases. MiRNA-148a- and galactose-induced mitochondrial oxidative stress activate c-Abl-mediated aggregation of α-syn which is exported by exosome release. Via the vagal nerve and/or systemic exosomes, toxic α-syn may spread to dopaminergic neurons and pancreatic β-cells linking the pathogenesis of PD and T2D.

Implications of liver donor age on ischemia reperfusion injury and clinical outcomes

The aging process causes detrimental changes in a variety of organ systems. These changes include: lesser ability to cope with stress, impaired repair mechanisms and decreased cellular functional reserve capacity. Not surprisingly, aging has been associated with increased susceptibility of donor heart and kidneys grafts to ischemia reperfusion injury (IRI). In the context of liver transplantation, however, the effect of donor age seems to be less influential in predisposing the graft to IRI. In fact, a widely comprehensive understanding of IRI in the aged liver has yet to be agreed upon in the literature. Nevertheless, there have been many reported implications of increased liver donor age with poor clinical outcomes besides IRI. These other poor outcomes include: earlier HCV recurrence, increased rates of acute rejection and greater resistance to tolerance induction. While these other correlations have been identified, it is important to re-emphasize the fact that a unified consensus in regard to liver donor age and IRI has not yet been reached among researchers in this field. Many researchers have even demonstrated that the extent of IRI in aged livers can be ameliorated by careful donor selection, strict allocation or novel therapeutic modalities to decrease IRI. Thus, the goals of this review paper are twofold: 1) To delineate and summarize the conflicting data in regard to liver donor age and IRI. 2) Suggest that careful donor selection, appropriate allocation and strategic effort to minimize IRI can reduce the frequency of a variety of poor outcomes with aged liver donations.

Intake of Milk or Fermented Milk Combined With Fruit and Vegetable Consumption in Relation to Hip Fracture Rates: A Cohort Study of Swedish Women

Milk products may differ in pro-oxidant properties and their effects on fracture risk could potentially be modified by the intake of foods with antioxidant activity. In the population-based Swedish Mammography Cohort study, we aimed to determine how milk and fermented milk combined with fruit and vegetable consumption are associated with hip fracture. Women born in 1914-1948 (n = 61,240) answered food frequency and lifestyle questionnaires in 1987-1990 and 38,071 women contributed with updated information in 1997. During a mean follow-up of 22 years, 5827 women had a hip fracture (ascertained via official register data). Compared with a low intake of milk (<1 glass/day) and a high intake of fruits and vegetables (≥5 servings/day), a high intake of milk (≥3 glasses/day) with a concomitant low intake of fruits and vegetables (<2 servings/day) resulted in a hazard ratio (HR) of 2.49 (95% CI, 2.03 to 3.05). This higher hip fracture rate among high consumers of milk was only modestly attenuated with a concomitant high consumption of fruit and vegetables (HR, 2.14; 95% CI, 1.69 to 2.71). The combination of fruits and vegetables with fermented milk (yogurt or soured milk) yielded a different pattern with lowest rates of hip fracture in high consumers: HR, 0.81 (95% CI, 0.68 to 0.97) for ≥2 servings/day of fermented milk and ≥5 servings/day of fruits and vegetables compared with low consumption of both fruit and vegetables and fermented milk. We conclude that the amount and type of dairy products as well as fruit and vegetable intake are differentially associated with hip fracture rates in women. © 2017 American Society for Bone and Mineral Research.

Milk, Fruit and Vegetable, and Total Antioxidant Intakes in Relation to Mortality Rates: Cohort Studies in Women and Men

High milk consumption might shorten life span through increased oxidative stress. We aimed to determine whether higher mortality rates with high milk consumption are modified by fruit and vegetable intake or total antioxidant intake (oxygen radical absorbance capacity). We used information from food frequency questionnaires completed by 61,420 women in a Swedish cohort (22,391 deaths from the 1987–1990 baseline onward), 36,714 women from a second survey (1997) of this cohort, and 45,280 Swedish men (15,478 deaths from the 1998 baseline onward). Compared with low consumption of milk (<1 glass/day) and high consumption of fruits/vegetables (≥5 servings/day), time-updated information revealed an adjusted hazard ratio for death of 2.79 (95% confidence interval (CI): 2.42, 3.21) in women who consumed ≥3 glasses of milk/day and <1 serving/day of fruit/vegetables and a hazard ratio of 1.60 (95% CI: 1.40, 1.82) in women who consumed the same amount of milk but ≥5 servings/day of fruits/vegetables. The same comparisons in men, based on a single food frequency questionnaire, displayed hazard ratios of 1.31 (95% CI: 1.14, 1.51) and 1.07 (95% CI: 0.97, 1.18), respectively. Total antioxidant consumption showed similar patterns as fruit/vegetable intakes. Dietary antioxidant intake, especially in women, seems to modify the elevated death rate associated with high milk consumption.

Serum Metabolite/Caffeine Ratios as a Test for Liver Function

The aim of this study was to test the usefulness of the metabolite/caffeine ratio for the evaluation of hepatic dysfunction. Subjects with liver cirrhosis and chronic hepatitis, as well as healthy volunteers, were given the oral dose of 300 mg caffeine. Blood samples were collected after 4, 8, and 12 hours. Concentrations of caffeine (CA) and its three metabolites-paraxanthine (PX), theobromine (TB), and theophylline (TP)-were determined by high-performance liquid chromatography. Pharmacokinetic parameters of caffeine and PX/CA, TB/CA, and TP/CA ratios were calculated. Elimination of caffeine was decreased in cirrhotics in comparison with healthy volunteers, as proved by the values of clearance (0.035 vs. 0.094 L/h/kg), elimination coefficient (0.061 vs. 0.153 h(-1)), and half-life (11.4 vs. 4.3 h). Serum metabolite/caffeine ratios were significantly reduced in cirrhotic patients: PX/CA by more than 80%, TB/CA by 50% to 70%, and TP/CA by 40% to 70%. The reduction of the ratios in chronic hepatitis patients was lower and did not occur at all time points. A high correlation was found between caffeine clearance and metabolite/caffeine ratios. Metabolite/caffeine ratios calculated in a single blood sample collected 8 or 12 hours after caffeine administration could provide a practical assessment of hepatic function in cirrhotic patients. The value of the test for the chronic hepatitis patients is limited.

Liver grafts from selected older donors do not have significantly more ischaemia reperfusion injury

BACKGROUND

There is a general concern that aged organs are more susceptible to ischaemia. In the light of recent proposals to change the liver allocation system by expanding regional sharing, it is feared that increased cold ischaemia time of grafts from older donors may reduce graft survival. The aim of this study was to correlate donor age and the patterns of ischaemia reperfusion injury and synthetic function early after liver transplantation.

METHODS

We performed a retrospective study of first transplants using a single-centre electronic database. Patterns of liver injury (based on transaminases and post-reperfusion biopsy), synthetic function (international normalized ratio [INR]), and graft and patient survival in recipients receiving liver grafts from donors aged ≥ 65 years (group 1, n= 50) were compared with equivalent patterns in a matched cohort of recipients transplanted with grafts from donors aged <65 years (group 2, n= 50).

RESULTS

There was no significant difference in transaminase levels from day 0 to day 6 after transplantation. When groups 1 and 2 were subdivided into two subgroups based on the duration of graft cold ischaemia time (<8 h and ≥ 8 h), there was no statistical difference in transaminase levels during the first 7 days. There were two cases (4%) of primary non-function in group 1 and one (2%) in group 2. Initial poor function did not differ significantly between the groups (26% vs. 24%; P= 0.81). In addition, there was no difference in histological changes in post-reperfusion biopsies (21% vs. 34%; P= 0.078) and rate of acute rejection episodes in the first year (30% vs. 32%; P= 0.99). There was no significant difference between groups 1 and 2 in 1-year patient and graft survivals (78% vs. 90% [P= 0.17]; 88% vs. 94% [P= 0.48], respectively).

CONCLUSIONS

Judiciously selected livers from aged donors are not associated with major increased susceptibility to ischaemia reperfusion injury.

Age-dependency of galactose elimination capacity in healthy children and children with chronic liver disease

OBJECTIVE

Galactose elimination capacity (GEC) is used as a quantitative measure of liver metabolic function with prognostic value in adults with acute and chronic liver failure. Almost no data are available regarding GEC in children, however. This study thus aims to meet the previously unmet clinical need for age-related data on GEC in children.

MATERIAL AND METHODS

We studied galactose elimination in 10 healthy children (median age 10.7 years; range 7 months to 16 years) and 30 children with chronic liver disease (median age 8.6 years; range 3 months to 16 years). GEC was estimated from the linear decrease in concentration of galactose in arterialized capillary blood from the ear following intravenous infusion of galactose.

RESULTS

In both groups of children, GEC (μmol/min/kg body weight) was highest in the youngest children and decreased with age, although at a significantly lower level in the children with liver disease (p = 0.05). GEC was significantly higher in healthy children than in healthy adults, diminishing to the adult level by the age of 16 years.

CONCLUSIONS

GEC was found to be higher in children than in adults until the age of 16 years. Moreover, GEC was significantly lower in children with chronic liver disease than in healthy children, underlining that GEC testing also has potential clinical usefulness as a quantitative measure of liver metabolic function in children.

Diagnosis and management of chronic liver disease in older people

Chronic liver disease is increasingly prevalent and, as the population ages, geriatricians will see an increasing burden. We present an overview of the investigation and management of older adults with chronic parenchymal liver disease and highlight the potential roles of transjugular intrahepatic portosytemic shunts and orthotopic liver transplantation.

The galactose elimination capacity and mortality in 781 Danish patients with newly-diagnosed liver cirrhosis: a cohort study

Background

Despite its biologic plausibility, the association between liver function and mortality of patients with chronic liver disease is not well supported by data. Therefore, we examined whether the galactose elimination capacity (GEC), a physiological measure of the total metabolic capacity of the liver, was associated with mortality in a large cohort of patients with newly-diagnosed cirrhosis.

Methods

By combining data from a GEC database with data from healthcare registries we identified cirrhosis patients with a GEC test at the time of cirrhosis diagnosis in 1992–2005. We divided the patients into 10 equal-sized groups according to GEC and calculated all-cause mortality as well as cirrhosis-related and not cirrhosis-related mortality for each group. Cox regression was used to adjust the association between GEC and all-cause mortality for confounding by age, gender and comorbidity, measured by the Charlson comorbidity index.

Results

We included 781 patients, and 454 (58%) of them died during 2,617 years of follow-up. Among the 75% of patients with a decreased GEC (<1.75 mmol/min), GEC was a strong predictor of 30-day, 1-year, and 5-year mortality, and this could not be explained by confounding (crude hazard ratio for a 0.5 mmol/min GEC increase = 0.74, 95% CI 0.59–0.92; adjusted hazard ratio = 0.64, 95% CI 0.51–0.81). Further analyses showed that the association between GEC and mortality was identical for patients with alcoholic or non-alcoholic cirrhosis etiology, that it also existed among patients with comorbidity, and that GEC was only a predictor of cirrhosis-related mortality. Among the 25% of patients with a GEC in the normal range (≥ 1.75 mmol/min), GEC was only weakly associated with mortality (crude hazard ratio = 0.79, 95% CI 0.59–1.05; adjusted hazard ratio = 0.80, 95% CI 0.60–1.08).

Conclusion

Among patients with newly-diagnosed cirrhosis and a decreased GEC, the GEC was a strong predictor of short- and long-term all-cause and cirrhosis-related mortality. These findings support the expectation that loss of liver function increases mortality.

PATIENT AGE IS A STRONG INDEPENDENT PREDICTOR OF 13C-AMINOPYRINE BREATH TEST RESULTS: A COMPARATIVE STUDY WITH HISTOLOGY, DUPLEX-DOPPLER AND A LABORATORY INDEX IN PATIENTS WITH CHRONIC HEPATITIS C VIRUS INFECTION

1. Noninvasive tests for the staging of chronic hepatitis C virus (HCV) infection would be an attractive alternative to liver biopsy. The 13C-aminopyrine breath test (ABT) has been proposed for the noninvasive assessment of hepatic function and partly correlates with fibrosis. We aimed to investigate causes for the lack of discriminatory power for different degrees of hepatic fibrosis. 2. Eighty-three patients (median age 49 years (28-78 years)) with chronic HCV infection underwent the ABT after an oral load of 75 mg N,N-dimethyl-13C-aminopyrine. Portal vein flow was assessed by duplex-Doppler and a laboratory index (aspartate aminotransferase to platelet ratio index or APRI) was calculated. Parameters were compared with liver histology. 3. The cumulative 13C-recovery differed significantly between patients without relevant fibrosis (fibrosis score 0-2) and cirrhosis (5-6), beginning after 30 min of sampling (P < 0.05). The ABT did not discriminate patients with fibrosis scores 3-4 from the remaining two patient groups. Sensitivity and specificity for the prediction of cirrhosis was 73.4-82.8% and 63.2-68.4%, depending on the sampling time. Compared with the fibrosis score (P = 0.04), patient age was a highly significant independent predictor for the 13C-recovery (P < 0.0001). Aspartate aminotransferase to platelet ratio index and duplex-Doppler predicted cirrhosis with 76.6%vs. 87.5% sensitivity and 63.2%vs. 68.4% specificity. 4. Our data suggest an age-dependent decrease of cytochrome P450 activity which probably accounts for the large overlap of ABT results that preclude clear differentiation. This is also consistent with former pharmacodynamic trials. Age-adapted reference ranges could improve ABT results.

Aging biology and geriatric clinical pharmacology

Population aging evokes doomsday economic and sociological prognostication, despite a minority of older people suffering significant dependency and the potential for advances in therapeutics of age-related disease and primary aging. Biological aging processes are linked mechanistically to altered drug handling, altered physiological reserve, and pharmacodynamic responses. Parenteral loading doses need only be adjusted for body weight as volumes of distribution are little changed, whereas oral loading doses in some cases may require reduction to account for age-related increases in bioavailability. Age-related reduction of hepatic blood flow and hepatocyte mass and primary aging changes in hepatic sinusoidal endothelium with effects on drug transfer and oxygen delivery reduce hepatic drug clearance. Primary renal aging is evident, although renal clearance reduction in older people is predominantly disease-related and is poorly estimated by standard methods. The geriatric dosing axiom, "start low and go slow" is based on pharmacokinetic considerations and concern for adverse drug reactions, not from clinical trial data. In the absence of generalizable dosage guidelines, individualization via effect titration is required. Altered pharmacodynamics are well documented in the cardiovascular system, with changes in the autonomic system, autacoid receptors, drug receptors, and endothelial function to modify baseline cardiovascular tone and responses to stimuli such as postural change and feeding. Adverse drug reactions and polypharmacy represent major linkages to avoidable morbidity and mortality. This, combined with a deficient therapeutic evidence base, suggests that extrapolation of risk-benefit ratios from younger adults to geriatric populations is not necessarily valid. Even so, therapeutic advances generally may convert healthy longevity from an asset of fortunate individuals into a general social benefit.

Differential pharmacokinetics of theophylline in elderly patients

The clinical use of theophylline as a first-line bronchodilator has declined during the last two decades. However, in many clinical settings, such as an emergency bronchial asthma attack, theophylline may have a first-line role, in combination with beta(2)-adrenoreceptor agonists and corticosteroids, for improving the asthmatic status. Furthermore, many therapeutic mechanisms of theophylline for bronchial asthma have been reported, and recent studies have suggested that theophylline therapy may have a beneficial role in the management of chronic stable asthma as well as exacerbated disease. However, theophylline has a low therapeutic index because the bronchodilation it produces has a linear relationship with logarithmic increases in serum concentration for the therapeutic range of 5-20 mg/L. Thus, the knowledge of its basic pharmacokinetics and the factors that can alter its clearance is clinically relevant for physicians. Especially when used in elderly asthmatic patients, dosage adjustment of theophylline is a requisite since the elderly have several risk factors that may increase the plasma theophylline level, such as reduced clearance, various underlying diseases and multiple coadministered drugs. After theophylline treatment has been initiated, therapeutic drug monitoring is required.

Study of liver function in healthy elderly subjects using the 13C-methacetin breath test

BACKGROUND

The issue of whether or not liver function is compromised in the healthy elderly population remains unsolved.

AIM

To investigate the putative age-related modifications of hepatic function using the 13C-methacetin breath test. Because endogenous CO2 production changes with age, motor activity and nutrition, a different form of processing the results was investigated.

PATIENTS AND METHODS

Twenty-nine elderly subjects (mean age, 79.8 +/- 7.9 years; female/male ratio, 17/12) and 28 adult subjects (mean age, 40.6 +/- 12.3 years; female/male ratio, 13/15) underwent 13C-methacetin breath test and trans-abdominal echosonography with Doppler pulsed wave analysis of the coeliac axis and portal vein.

RESULTS

Although the 13CO2 peak occurred within 15-30 min in both elderly and adult subjects, it was significantly decreased in the former (30.66% +/- 9.2% vs. 38.33% +/- 6.05%; P < 0.001), as was the cumulative excretion (33.07% +/- 7.06% vs. 39.81% +/- 5.68%; P < 0.001). When correcting for the effects of CO2 excretion by age, the age-related modification of the cumulative dose became more evident (elderly group 30.15% +/- 6.46% vs. adult group 37.97% +/- 5.92%; P < 0.0001). The elderly group also showed an increase in the intra-hepatic resistance index using Doppler pulsed wave analysis, which inversely correlated with the results of the breath test.

CONCLUSIONS

Hepatic function is not well preserved in healthy humans throughout life and may be due to an increase in vascular resistance.

Review article: breath testing for human liver function assessment

Carbon-labelled breath tests were proposed as tools for the evaluation of human liver function 30 years ago, but have never become part of clinical routine. One reason for this is the complex role of the liver in metabolic regulation, making it difficult to provide essential information for the management of patients with liver disease with a single test and to satisfy the hepatology community. As a result, a battery of breath tests have been developed. Depending on the test compound administered, different metabolic pathways (microsomal, cytosolic, mitochondrial) can be examined. Most available data come from microsomal function tests, whilst information about cytosolic and mitochondrial liver function is more limited. However, breath tests have shown promise in some studies, in particular to predict the outcome of patients with chronic liver disease or to monitor hepatic function after treatment. Whilst we await new substrates that can be used to measure liver function in a more valid manner, and large prospective studies to assess the usefulness of available test compounds, the aim of this review is to describe how far we have come in this controversial and unresolved issue.

Liver function and phase I drug metabolism in the elderly: a paradox

Aging is accompanied by marked changes in the physiology of many organs, as well as in their constituent cells. These nonpathological alterations in structure and/or function may affect normal physiological processes in the elderly (individuals > 65 years), for example drug disposition. The liver plays a major role in drug clearance and aging has been reported to diminish this hepatic capacity, particularly the clearance of drugs that undergo mandatory oxidation by the microsomal cytochrome P450-dependent mono-oxygenase systems. Liver volume and blood flow decline with age in humans and, no doubt, this contributes to the diminished clearance of drugs that exhibit first-pass kinetic profiles. Changes in liver morphology with aging that have been described in rodents are limited to the hepatocytes, for example accumulation of dense bodies and loss of smooth surfaced endoplasmic reticulum. There is no evidence that the increase in intracellular lipofuscin adversely affects hepatocyte functions. A number of studies have documented significant age-related declines in the amounts, specific activities and rates of induction of liver microsomal mono-oxygenases in inbred male rats. On the basis of a variety of clinical tests, most liver functions in humans appear to be well preserved. The most remarkable characteristic of liver function in the elderly is the increase in interindividual variability, a feature that may obscure age-related differences. Most in vitro studies using nonhuman primate or human liver tissue did not detect age-related deficiencies in cytochrome P450-dependent microsomal mono-oxygenases. On the other hand, there have been recent reports of age-related, but not gender-related, declines in the in vitro activities of several human liver mono-oxygenases, for example the cytochrome P450 isoform CYP3A. Nevertheless, reduced liver volume and blood flow in the elderly permit the reconciliation of: the in vivo clinical pharmacokinetic data indicative of reduced hepatic drug clearance; and the absence of significant age-related declines in the amounts or in vitro activities of liver microsomal mono-oxygenases.

Drug treatment of the complications of cirrhosis in the older adult

Several age-related changes occur in the structure and functions of the liver. The volume of the liver decreases, despite an increase in the size of hepatocytes, suggesting loss of liver cells. There are decreases in hepatic blood flow, the synthesis of urea and cholesterol, and the metabolism of drugs. Moreover, the regenerative capacity of liver becomes less efficient. Certain caveats are important when treating older patients with liver disease. Strict dietary restrictions, such as a low protein diet, should be avoided in the elderly (unless the patient is encephalopathic) because these patients are often undernourished to start with. Similarly, strict salt restriction should be enforced with caution, since it makes food less palatable and may take away what little desire such patients have to eat. Diuretic doses should be adjusted carefully because of greater risks of azotaemia and electrolyte disturbances in the elderly. Extra vigilance should be exercised in the early detection of infections that are more likely to occur in patients with cirrhosis. For example, spontaneous bacterial peritonitis can be missed in the elderly because of poor systemic (fever, abdominal tenderness) and laboratory responses (leucocytosis). In patients presenting with acute variceal bleeding, it is better to err on the side of underhydration than overhydration because of the risk of congestive heart failure. Vasopressin should be avoided in the elderly, since this drug has a high probability of precipitating an ischaemic event. Older patients do not tolerate beta-blockers as well as younger individuals and may require other treatment strategies for the prevention of variceal rebleeding episodes. Hepatic encephalopathy, especially the milder form, needs careful assessment because it can be easily confused with senile dementia syndromes. Cirrhosis is a premalignant condition and patients are at increased risk of developing hepatocellular carcinoma (HCC), a tumour seen predominantly in the elderly. All patients with cirrhosis should be maintained on a lifelong screening programme consisting of a 6-monthly assessment of alpha-fetoprotein and an imaging study, since early detection provides the only hope for cure of HCC. The only definitive treatment of cirrhosis is liver transplantation. Advanced age is not a contraindication to transplantation, and survival in older patients (aged >60 years) is comparable to that in younger individuals.

Is there evidence for an age-related reduction in metabolic rate?

To determine whether the age-related reduction in basal metabolic rate (BMR) is explained by a quantitative and/or qualitative change in the components of lean tissue, we conducted a cross-sectional study in groups of young (n = 38, 18-35 yr) and older (n = 24, 50-77 yr) healthy individuals. BMR was measured by indirect calorimetry. Body composition was obtained by using dual-energy X-ray absorptiometry (DEXA), which permitted four compartments to be quantified [bone mineral mass, fat mass (FM), appendicular lean tissue mass (ALTM), and nonappendicular lean tissue mass (NALTM)]. Absolute BMR and ALTM were lower, whereas FM was significantly higher in the older, compared with young, subjects. BMR, adjusted for differences in FM, ALTM, and NALTM, was significantly lower in the older subjects by 644 kJ/day. In separate regression analyses of BMR on body compartments, older subjects had significantly lower regression coefficients for ALTM and NALTM, compared with young subjects. Hence, the age-related decline in BMR is partly explained by a reduction in the quantity, as well as the metabolic activity, of DEXA-derived lean tissue components.

The aging liver. Drug clearance and an oxygen diffusion barrier hypothesis

A change in drug clearance with age is considered an important factor in determining the high prevalence of adverse drug reactions associated with prescribing medications for the elderly. Despite this, no general principles have been available to guide drug administration in the elderly, although a substantial body of clearance and metabolism data has been generated in humans and experimental animals. A review of age-related change in drug clearances established that patterns of change are not simply explained in terms of hepatic blood flow, hepatic mass and protein binding changes. In particular, the maintained clearance of drugs subject to conjugation processes while oxygen-dependent metabolism declines, and all in vitro tests of enzyme function have been normal, requires new explanations. Reduction in hepatic oxygen diffusion as part of a general change in hepatocyte surface membrane permeability and conformation does provide one explanation for the paradoxical patterns of drug metabolism, and increased hepatocyte volume would also modify oxygen diffusion path lengths (the 'oxygen diffusion barrier' hypothesis). The reduction in clearances of high extraction drugs does correlate with observed reduction in hepatic perfusion. Dosage guidelines emerge from these considerations. The dosage of high clearance drugs should be reduced by approximately 40% in the elderly while the dosage of low clearance drugs should be reduced by approximately 30%, unless the compound is principally subject to conjugation mechanisms. If the hepatocyte diffusion barrier hypothesis is substantiated, this concept may lead to therapeutic (preventative and/or restorative) approaches to increased hepatocyte oxygenation in the elderly. This may lead to approaches for modification of the aging process in the liver.

Evaluation of pharmacokinetic methods used to estimate caffeine clearance and comparison with a Bayesian forecasting method

Simplified pharmacokinetic methods have been used to estimate caffeine clearance in subjects with liver disease. There is a need to have a reliable, easy to implement method for research and possible clinical use. This study evaluates the use of Bayesian pharmacokinetic forecasting techniques to estimate caffeine clearance and compares its performance to other published methods. Commonly used published methods include the two-concentration overnight salivary clearance method (Jost method) and a method that samples caffeine concentrations over a 4-hour time period (Nagel method). Both have been used in studies incorporating serial measurements of caffeine clearance to predict clinical outcomes in subjects with liver disease, but these approaches have not been proven useful. However, neither method has been formally evaluated for accuracy in estimating caffeine clearance in subjects with cirrhosis. The performance of the Jost, Nagel, and Bayesian methods was compared to a Gold Standard method that accurately measured caffeine clearance in healthy subjects and subjects with cirrhosis using an intravenous infusion of stable isotope-labeled caffeine. The Bayesian method, even when only one measured concentration of caffeine was used, was more accurate, better correlated to the Gold Standard method, and had less intraindividual variation than the two previously published methods. Before the idea of using serial measurements of caffeine clearance for clinical usefulness is rejected, a reevaluation using methods of estimating caffeine clearance that are more accurate than previous paradigms is needed.

Xenobiotic-induced hepatotoxicity: mechanisms of liver injury and methods of monitoring hepatic function

Xenobiotic-induced liver injury is a clinically important etiology of hepatic disease that, if not recognized, can lead to hepatic failure. In this article we discuss the mechanisms of xenobiotic-induced liver injury, various factors that can alter the risk and severity of injury, the clinical and laboratory manifestations of injury, and the methods used to detect the presence of injury and (or) functioning liver mass.

Oxygen consumption in the heart, hepatomesenteric bed, and brain in young and elderly human subjects, and accompanying sympathetic nervous activity

Although the reduction in whole-body energy expenditure with aging has been well documented, there is little information about the changes that individual organs undergo. We therefore measured oxygen consumption in the heart, hepatomesenteric bed, and brain in elderly subjects and young controls, using central venous catheter techniques and the application of Fick's principle. We also measured whole-body, cardiac, and hepatomesenteric sympathetic nervous activity using isotope dilution methodology. Cardiac, hepatomesenteric, and cerebral oxygen consumption was similar in both groups. Whole-body and hepatomesenteric sympathetic nervous activity was also similar in the study groups, whereas cardiac norepinephrine (NE) spillover was significantly higher in the elderly. In contrast to the young, cardiac sympathetic nervous activity as assessed from NE spillover was not related to either cardiac oxygen consumption or cardiac work in the elderly. The data suggest that although oxygen consumption in the heart, hepatomesenteric bed, and brain are not different between young and elderly individuals, the relationship between sympathetic nervous activity and oxygen consumption in individual organs may alter with aging.

Liver function tests

For optimal timing of liver transplantation and for the evaluation of new pharmacotherapeutic options, objective modalities for estimating the liver's functional reserve and prognosis in an individual patient are highly desirable. In the past a number of tests and several scoring systems have been proposed and validated to varying degrees for this purpose. The issues still to be clarified include: (1) any observed prognostic value of individual quantitative function tests and of scoring systems must be validated in independent, large enough and well defined patient populations; (2) it must be prospectively defined which (serially performed) quantitative test(s) add(s) prognostic information for the individual patient to the survival estimates defined by the more universally available scores and in which disease state(s); and (3) existing scoring systems must be validated, or new ones developed, that allow follow-up data to be used in order to adapt the original prognosis estimate to the evolution of the disease, e.g. during therapy.

Significance of aminopyrine breath test as a parameter of hepatic functional reserve in 40% partial hepatectomy of rats with CCl4-induced liver injury

Rats with CCl4-induced liver injury underwent partial (40%) hepatectomy. The [14C]aminopyrine breath test (ABT) values in rats with CCl4-induced liver injury were reduced by 34% compared with those in rats with normal liver. Preoperative ABT values clearly discriminated between survivors and those that died following 40% partial hepatectomy in rats CCl4-induced liver injury (P < 0.05). Hepatic protein synthesis was remarkably enhanced in CCl4-induced liver injury compared with normal liver (P < 0.001), and this was inversely correlated with ABT values (P < 0.001). These data show that the enhanced hepatic protein synthesis could induce a decrease of hepatic functional reserve. ABT seems to be a useful preoperative test for predicting surgical mortality following hepatectomy.

Occult caffeine as a source of sleep problems in an older population

OBJECTIVE

To evaluate the impact of caffeine in medication on sleep complaints in a community population of persons aged 67 or older.

DESIGN

Cross-sectional analysis.

SETTING

Iowa 65+ Rural Health Study.

PARTICIPANTS

Those who completed their own interview, including a section on the use of medications, during the third annual in-person follow-up in 1984-1985.

MEASUREMENTS

MAIN OUTCOMES

trouble falling asleep or other sleep complaints. Covariates: use of caffeine-containing medication, spasmolytic, or sympathomimetic drug; number of drugs used; depressive symptoms; self-perceived health; comorbidity, hip fracture, arthritis, ulcer of stomach or intestines; and consumption of caffeinated beverages.

RESULTS

The prevalence of caffeinated medication use by participants was 5.4%. Those reporting the use of any caffeine-containing medication were at an increased risk of having trouble falling asleep (Odds Ratio [OR] = 1.79, 95% confidence interval [CI] = 1.19-2.68). There was no significant risk of other reported nighttime or daytime sleep problems associated with use of caffeine-containing drugs. Even after adjusting for other factors that could interfere with initiation of sleep, such as painful disease, depressive symptoms, polypharmacy, use of specific medications known to interfere with sleep, and coffee consumption, the use of caffeine-containing medication still presented a significantly increased risk of having trouble falling asleep (OR = 1.60, CI = 1.04-2.46). Although those participants using over-the-counter analgesic medication containing caffeine had an increased risk of trouble falling asleep (OR = 1.88, CI = 1.22-2.90), there was no significant risk of trouble falling asleep for those who took similar noncaffeinated OTC analgesic drugs (OR = 1.26, CI = 0.87-1.83).

CONCLUSIONS

The use of caffeine-containing medication is associated with sleep problems. Healthcare providers should be aware of potential problems associated with over-the-counter medications containing caffeine and should counsel patients about the potential of sleep problems. Older patients should be encouraged to read the label on medications and to select drugs that are caffeine-free when that is possible.

Kinetics of hepatic amino-nitrogen conversion in ageing man

Previous studies have shown that hepatic function, quantitatively measured by dynamic liver function tests, progressively declines with ageing. Urea synthesis is a specific process taking place in the liver; a reduced urea synthesis in response to a protein-rich metal has previously been demonstrated in the elderly, but the process has never been standardized in relation to amino acid supply. We measured the hepatic conversion of alpha-amino nitrogen into urea nitrogen in response to alanine infusion in 32 subjects, with normal routine liver and renal function tests and without evidence of previous hepatic disorders, belonging to three different age-groups (< or = 55 years, 56-70, > or = 71). The functional hepatic nitrogen clearance was reduced on average by 20% in subjects aged 56-70 years, and by 30% in subjects over 70 years old in comparison to the age-group under 55 years (ANOVA: P = 0.0001), and significantly correlated with age (r = -0.684). No sex differences were observed on the effects of age on hepatic clearance. Also, liver volume, measured by ultrasonography, was reduced with advancing age, but the age-related decrease in hepatic nitrogen conversion was not primarily dependent on decreased liver volume. The measurement of functional hepatic nitrogen clearance has already been validated as a quantitative liver function test in clinical hepatology. In keeping with previous studies, the age-related decline in hepatic nitrogen conversion points to a decreased functional capacity of the ageing hepatic parenchyma.

Microsomal liver function declines steadily after kidney grafting: a three to five year follow-up

We have previously shown that the functioning hepatocyte mass (galactose elimination capacity, GEC) and microsomal liver functions (non-renal clearances of unbound prednisolone and cyclosporin A) are impaired in renal allograft recipients (N = 28) one month and one year after successful transplantation. To assess the natural history of these hepatic functional derangements, we reinvestigated 21 patients with stable renal function three to five years following grafting. GEC remained with 6.07 +/- 0.86 mg/min x kg significantly (P less than 0.001) below that in healthy controls (7.52 +/- 0.78 mg/min x kg), but did not significantly change during follow-up (5.93 +/- 0.96 and 6.26 +/- 0.94 mg/min x kg at 1 year and 1 month, respectively). In contrast, the non-renal clearance of unbound prednisolone declined steadily during follow-up averaging 4.98 +/- 0.71 ml/min x kg at three to five (compared to 5.83 +/- 1.51 and 6.80 +/- 1.73 ml/min x kg at one year and one month, respectively). These values were lower (P less than 0.01) than those observed in healthy control subjects (7.56 +/- 1.59 ml/min x kg). The total body clearance of cyclosporin A decreased similarly with time averaging 4.5 +/- 1.2 ml/min x kg at three to five years (compared to 4.9 +/- 1.2 and 5.9 +/- 2.1 ml/min x kg at 1 year and 1 month, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of caffeine in patients with decompensated type I and type II diabetes mellitus

Diabetes may alter the pharmacokinetics of aminopyrine and antipyrine, which are used to assess liver function. Caffeine has recently been used to test liver function, but the effect of diabetes on caffeine kinetics is not known. The kinetics of caffeine has been examined in patients with decompensated Type I and Type II diabetes and in two age- and sex-matched control groups. In both types of diabetes the apparent caffeine clearance, half-life, and apparent volume of distribution were similar to controls. It is concluded that decompensated diabetes does not influence the cytochrome P-448 mono-oxygenase system responsible for caffeine metabolism.

Hepatic drug metabolism and aging

Although there is considerable variation in the effect of age on drug biotransformation, the metabolism of many drugs is impaired in the elderly. Age-related physiological changes, such as a reduction in liver mass, hepatic metabolising enzyme activity, liver blood flow and alterations in plasma drug binding may account for the decreased elimination of some metabolised drugs in the elderly. It is difficult, however, to separate an effect of aging from a background of marked variation in the rate of metabolism due to factors such as individual metabolic phenotype, environmental influences, concomitant disease states and drug intake. The prevailing data suggest that initial doses of metabolised drugs should be reduced in older patients and then modified according to the clinical response. In most studies the elderly appear as responsive as young individuals to the effects of compounds which induce or inhibit the activity of cytochrome P450 isozymes. Concurrent use of other agents, which induce or inhibit drug metabolism, mandates dose adjustment as in younger patients. Many questions remain unanswered. For instance, limitations of in vitro studies prevent any firm conclusion about changes in hepatic drug metabolising enzyme activity in the elderly. With aging, some pathways of drug metabolism may be selectively affected, but this has not been adequately scrutinised. The possibility that metabolism of stereoisomers may be altered in the elderly has not been adequately tested. The effect of aging on the distribution of polymorphic drug metabolism phenotypes is still not established, despite potential implications for disease susceptibility and survival advantage.

Age-associated decline of hepatic handling of cholephilic anions in humans is reverted by S-adenosylmethionine (SAMe)

Decreased fluidity of hepatocyte plasma membrane may contribute to the age-associated changes of liver function. This study aimed at investigating whether the hepatic clearance of organic anions declines with age and whether S-adenosylmethionine (SAMe), a substance proven to be effective in reversing the age-related decrease of membrane fluidity, might influence this process. Nicotinic acid (NA) half-life and serum bilirubin pharmacokinetics after NA load (5.9 mumol/kg body weight i.v.) were studied in 10 healthy young males (YM) aged 14-28 years and in 10 healthy elderly males (EM) aged 65-81 years, before and after SAMe administration (800 mg/day intravenously for 10 days). At baseline, EM showed serum total bilirubin (STB) levels significantly higher than YM. Similarly, the bilirubinaemic mean curves, STB peak and STB time curve concentration after NA load, expressed as area under the curve (AUC), were significantly higher in EM than in YM (p less than 0.01). NA half-life was also significantly prolonged in the aged group (p less than 0.001). SAMe treatment was followed by a significant decrease of basal STB, STB peak and AUC of STB after NA load in EM (p less than 0.01 vs pre-treatment values) while NA half-life was significantly shortened in both groups (p less than 0.001). As NA and bilirubin share a common carrier protein for hepatic uptake, bilitranslocase, the changes observed in EM may be attributed to the reduced lateral mobility of hepatocyte plasma membrane proteins occurring with age. SAMe, by improving membrane fluidity, may increase the diffusion coefficient of bilitranslocase restoring the hepatic handling of organic anions.

Exercise-induced hyperammonemia in patients with compensated chronic liver disease

Plasma levels of ammonia and amino acids were measured during and after graded physical exercise in seven ambulatory patients with well-compensated chronic liver disease and in seven healthy controls. Plasma ammonia was similar in both groups at rest but reached significantly higher peak values (124.0 +/- 29.3 (SD) versus 74.7 +/- 17.7 mumol/l) in the patients with liver disease during exercise. The return to base line during the recovery period was delayed in the patients (T1/2 9.9 +/- 5.5 versus 2.3 +/- 1.0 min). Except for plasma taurine, which was significantly lower in the patients at rest and which showed a significant decrease in the controls but not in the patients during exercise, changes in the plasma concentration of amino acids were similar in the two groups. The increased exposure of patients with chronic liver disease to ammonia while performing an identical workload results from an impaired clearance of ammonia plus, possibly, an increased generation of ammonia in muscle working at a higher intensity. Since hyperammonemia may be associated with the sensation of fatigue, increases in plasma ammonia during daily physical activities might in part explain the easy fatigability often reported by patients with chronic liver disease.

Use of quantitative liver function tests--caffeine clearance and galactose elimination capacity--after orthotopic liver transplantation

To establish the potential value of quantitative tests of liver function following orthotopic liver transplantation (OLT), a total of 100 determinations of caffeine clearance (CafCl) and galactose elimination capacity (GEC) were made in ten OLT recipients early in the post-operative course (days 2, 4, 6, 8 and 12) and later when clinically stable (3-12 months). Values were compared with a reference range in six normal volunteers in whom it was shown that the standard doses of caffeine (125 mg) and galactose (0.5 g per kg body weight) could be given together without interference. In orthotopic liver transplantation recipients initial GEC and CafCl measurements showed no correlation with peri-operative blood loss, donor ischaemia time, initial bile flow or survival. Throughout the early post-operative period, there were wide inter- and intra-individual variations in both CafCl (17-fold range from 0.16 to 2.7 ml.min-1.kg-1) and GEC (2.4-fold range from 5.1 to 12 mg.min-1.kg-1), but the only correlation of test values with standard liver function tests results was between GEC and gamma-glutamyltranspeptidase. However, GEC values fell by 19% during periods of acute rejection and there was an inverse correlation of GEC with white cell count probably related to sepsis.(ABSTRACT TRUNCATED AT 250 WORDS)

Liver mitochondrial respiratory functions decline with age

Human liver mitochondrial respiration rates in Chinese populations of various ages were assayed with an oxygraph. In this study, State 3 and State 4 respiration rates, respiratory control ratio (RCR), and ADP/O ratio were measured for 35 Chinese subjects of 31 to 76 years old. We found a significant negative correlation between age and respiratory control and ADP/O ratios tested. Moreover, the respiratory control and ADP/O ratios decreased with the increase of age. These findings suggest that a substantial fall in mitochondrial oxidative capacity in ageing liver may be an important contributor to the ageing process.

Age dependence of rat liver function measurements

Changes in the galactose elimination capacity, the capacity of urea-N synthesis and antipyrine clearance were studied in male Wistar rats at the age of 8, 20 and 44 weeks. Further, liver tissue concentrations of microsomal cytochrome P-450, microsomal protein and glutathione were measured. All liver function measurements increased from the age of 8 to 44 weeks when expressed in absolute values. In relation to body weight, these function measurements were unchanged or reduced from week 8 to week 20. At week 44, galactose elimination capacity and capacity of urea-N synthesis related to body weight were increased by 10% and 36%, respectively, and antipyrine plasma clearance was reduced to 50%. Liver tissue concentrations of microsomal cytochrome P-450 and microsomal protein increased with age when expressed in absolute values, but were unchanged per g liver, i.e., closely related to liver weight in the age range studied. Glutathione showed an increase of 35% from 8 to 44 weeks of age expressed per g liver. Careful age matching of control animals is important for experimental rat studies.

Effect of phenytoin, carbamazepine, and valproic acid on caffeine metabolism

Three groups of non-smoking epileptic patients without liver disease receiving antiepileptic monotherapy have been compared with 10 healthy non-smoking volunteers. Group 1 received phenytoin (n = 10), Group 2 carbamazepine (n = 10) and Group 3 valproic acid (n = 6). Cytochrome P-450 activity was monitored by measuring urinary 6-beta-hydroxycortisol output and systemic antipyrine clearance. Both, 6-beta-hydroxycortisol output and antipyrine clearance were significantly enhanced in patients on phenytoin and carbamazepine, but not in those on valproic acid. On the other hand, phenytoin alone increased the clearance of caffeine from 1.5 (controls) to 3.6 ml.min-1.kg-1, and reduced its half life from 4.8 to 2.4 h. Carbamazepine and valproic acid had no effect on caffeine metabolism. The results are in keeping with the well known heterogeneity of the hepatic monooxygenase system, as phenytoin and carbamazepine induce different panels of cytochrome P-450 isoenzymes. Phenytoin treatment may impair the validity of the caffeine liver function test.

Preserved cytosolic and synthetic liver function in jaundice of severe extrahepatic infection

We investigated prospectively 9 adult patients with the syndrome of jaundice complicating severe extrahepatic infection both clinically and by quantitative liver function tests. Five patients having severe extrahepatic infection without jaundice were used for comparison. Intraperitoneal infection was found to be a major risk factor for development of jaundice. Jaundice was mainly associated with gram-negative infection, but did not influence survival. Duration of jaundice was dependent on control of the underlying infection. Liver function tests showed a severely deranged organic anion transport, whereas synthetic, cytosolic, and microsomal functions remained preserved. Our study shows that (a) the syndrome of jaundice associated with extrahepatic infection is a functional disorder that is reversible upon control of infection, and that (b) cytosolic, synthetic, and microsomal function is preserved. This may have consequences for both assessing prognosis and clinical management.

Impaired liver function in stable renal allograft recipients

Hepatic failure as a cause of death is increased in stable renal allograft recipients when compared with patients on dialysis. In order to assess the magnitude and the natural history of the hepatic functional derangement, the kinetics of xenobiotics which are metabolized by cytosolic (galactose) or microsomal (prednisolone, cyclosporine A) enzymes were determined in 28 consecutive stable kidney transplant patients 1 month and 1 year after transplantation. Renal transplant patients had a decreased mean (+/- S.D.) galactose elimination capacity at 1 month (6.26 +/- 0.94 mg per min x kg) and at 1 year (5.93 +/- 0.96 mg per min x kg), when compared with a different group of 28 healthy control subjects (7.52 +/- 0.78 mg per min x kg, p less than 0.001) and a decreased total body clearance of prednisolone at 1 month (2.13 +/- 0.34 ml per min x kg vs. 2.71 +/- 0.43 ml per min x kg in controls, p less than 0.001), which further decreased over the following year to 1.76 +/- 0.32 ml per min x kg (p less than 0.001). The clearance of cyclosporine A declined significantly during the first year of successful transplantation (5.9 +/- 2.1 ml per min x kg vs. 4.9 +/- 1.2 ml per min x kg, p less than 0.05). In conclusion, a substantial proportion of stable renal transplant recipients have decreased cytosolic and microsomal liver functions despite the absence of clinical and laboratory evidence of significant liver disease.

The effect of age upon liver volume and apparent liver blood flow in healthy man

The aim of this study was to determine the effect of aging upon liver volume and apparent liver blood flow in healthy man. Sixty-five subjects between 24 and 91 years of age were recruited. Liver volume was quantitated by a gray scale B ultrasound scan method. Apparent liver blood flow was determined from the plasma clearance of indocyanine green, based on an assumption of no change in hepatic extraction of the dye with age. A significant negative correlation was observed between age and both liver volume and apparent liver blood flow (p less than 0.001), whether expressed in absolute terms or per unit body weight. Similarly, a significant negative correlation was observed between apparent liver blood flow per unit volume of liver (liver perfusion) and age (p less than 0.005). The reduction in liver volume, apparent liver blood flow and perfusion may at least partly account for the decline in the clearance of many drugs undergoing liver metabolism which has been noted to occur with aging in man.

Age-related changes in liver size and hepatic blood flow. The influence on drug metabolism in the elderly

The propensity of elderly people to suffer from dose-dependent adverse drug reactions is well known. This may be largely related to reduced drug clearance. Changes in liver size and liver blood flow are probably the main reason for this decline in drug elimination with age. This review focuses on methods of measuring liver size and blood flow, on changes which have been reported in the elderly and on the clinical implications of these changes.

Galactose elimination capacity and liver volume in aging man

The galactose elimination capacity, a measure of the functional liver cell mass, and liver volume were measured in 50 normal subjects of five different age groups (less than 50, 51 to 60, 61 to 70, 71 to 80 and greater than 81 years). The volume of the liver was evaluated by ultrasonography. All subjects had normal routine liver function tests and no history of liver disease. Galactose elimination progressively decreased from 3.05 +/- 0.58 (S.D.) mmoles per min in younger subjects to 1.83 +/- 0.24 mmoles per min in subjects over 81 (p less than 0.00003), without any change in the apparent volume of distribution of the sugar. Similarly, the estimated volume of the liver decreased from 110 +/- 14 units to 75 +/- 13 units with increasing age (p less than 0.0002). Both galactose elimination capacity and the estimated liver volume inversely correlated with age (r = -0.728 and r = -0.579, respectively) whereas a positive correlation was observed between galactose elimination and the estimated liver volume (r = 0.520). Part correlation analysis confirmed that age, when entered in a multiple regression already containing body weight and estimated liver volume as independent variables, had a significant effect on liver function, whereas no significant independent effect of liver volume was present. Both age and body weight had a significant independent effect on the estimated liver volume. The maximum functional capacity of the liver, measured by galactose elimination, is reduced in the elderly. Although several factors may play a role, our data suggest that aging is associated with a slight decline in the intrinsic metabolic activity of the hepatic parenchyma.