Gastrointestinal and Liver Function in Old Age

PMK-S005 Alleviates Age-Related Gastric Acid Secretion, Inflammation, and Oxidative Status in the Rat Stomach

Background/Aims

The aim of this study was to evaluate the effect of the synthetic S-allyl-l-cysteine (SAC) PMK-S005 on gastric acid secretion, inflammation, and antioxidant enzymes in aging rats.

Methods

The rats were divided into four groups at 31 weeks of age and were continuously fed a diet containing a vehicle control, PMK-S005 (5 or 10 mg/kg), or lansoprazole (5 mg/kg). Gastric acid secretion and connective tissue thickness of the lamina propria were evaluated at 74 weeks and 2 years of age. Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and COX-2 levels were measured by using enzyme-linked immunosorbent assays (ELISAs) or Western blot assays. Levels of antioxidant enzymes, including heme oxyganase 1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO-1), were also measured.

Results

As the rats aged, gastric acid secretion significantly decreased, and the connective tissue of the lamina propria increased. However, 74-week-old rats in the PMK-S005 group exhibited greater levels of gastric acid secretion than those of the control and lansoprazole groups. The increase of TNF-α, IL-1β, and COX-2 expression in 74-week and 2-year-old control rats were inhibited by PMK-S005. In addition, the decrease in HO-1 and NQO-1 protein expression that occurred with aging was inhibited by PMK-S005 in the 74-week-old rats.

Conclusions

These results suggest that PMK-S005 has therapeutic potential as an antiaging agent to ameliorate age-related gastric acid secretion, inflammation, and oxidative stress in the stomach.

Kidney and liver transplantation in the elderly

BACKGROUND

Transplant surgery is facing a shortage of deceased donor organs. In response, the criteria for organ donation have been extended, and an increasing number of organs from older donors are being used. For recipients, the benefits of transplantation are great, and the growing ageing population has led to increasing numbers of elderly patients being accepted for transplantation.

METHODS

The literature was reviewed to investigate the impact of age of donors and recipients in abdominal organ transplantation, and to highlight aspects of the fine balance in donor and recipient selection and screening, as well as allocation policies fair to young and old alike.

RESULTS

Overall, kidney and liver transplantation from older deceased donors have good outcomes, but are not as good as those from younger donors. Careful donor selection based on risk indices, and potentially biomarkers, special allocation schemes to match elderly donors with elderly recipients, and vigorous recipient selection, allows good outcomes with increasing age of both donors and recipients. The results of live kidney donation have been excellent for donor and recipient, and there is a trend towards inclusion of older donors. Future strategies, including personalized immunosuppression for older recipients as well as machine preservation and reconditioning of donor organs, are promising ways to improve the outcome of transplantation between older donors and older recipients.

CONCLUSION

Kidney and liver transplantation in the elderly is a clinical reality. Outcomes are good, but can be optimized by using strategies that modify donor risk factors and recipient co-morbidities, and personalized approaches to organ allocation and immunosuppression.

Liver function following extended hepatectomy can be accurately predicted using remnant liver volume to body weight ratio

BACKGROUND

Standardised measurement of remnant liver volume (RLV), where total liver volume (TLV) is calculated from patients' body surface area (RLV-sTLV), has been advocated. Extrapolating the model of living donor liver transplantation, we showed in a pilot study that the simplified RLV/body weight ratio (RLVBWR) was accurate in assessing the functional limit of hepatectomy. The aim of the study was to compare in a prospective series of extended right hepatectomy the predictive value of the RLVBWR and the RLV-sTLV at a cut-off of 0.5% (RLVBWR0.5%) and 20% (RLV-sTLV20%), respectively.

METHODS

We studied the impact of RLVBWR0.5% and of RLV-sTLV20% on three months morbidity and mortality in 74 non-cirrhotic patients operated on for malignant tumours. Of these, 47 patients who were not included in the initial pilot study were enrolled in a prospective validation cohort to reappraise the predictive value of each method.

RESULTS

RLVBWR and RLV-sTLV were highly correlated (Pearson correlation coefficient, 0.966). Three months overall and severe morbidity (grade 3b-5) and mortality were significantly increased in groups RLVBWR ≤ 0.5% and RLV-sTLVs ≤ 20% compared to groups >0.5% and >20%, respectively. The sensitivity and specificity in predicting death from liver failure were 100 and 84.1% for RLVBWR0.5% and 60 and 94.2% for RLV-sTLV20%, respectively. Similar results were observed in the validation cohort for the RLVBWR0.5% (lack of statistical power for RLV-sTLV as only 2 patients showed a RLV-sTLV ≤ 20%).

CONCLUSIONS

The RLVBWR0.5% is a method of assessing the remnant liver that is simple and as reliable as the standardised RLV-sTLV20%.

Advanced age remains an achilles heel for liver resections

BACKGROUND

As the general population is aging, surgery in elderly patients has become a major public health issue. This basic question is especially true for liver resection (LR). The aim of this study was to evaluate the operative risks of LR in the elderly.

METHODS

Retrospective analysis of a large recent and monocentric database of LR was performed between January 1, 2005 and May 31, 2011. Patients were categorized into three groups (<60, 60-74, and ≥75 years old) to analyze postoperative outcomes and 1-year mortality. Clinicopathologic factors likely to influence outcomes were assessed by univariate and multivariate analysis.

RESULTS

Altogether, 1,001 consecutive LRs were performed in 912 patients (mean age 62 ± 13 years). The distribution of the LR by age was 372 (37.2 %), 477 (47.6 %), and 152 (15.2 %) in patients <60, 60-74, and ≥75 years, respectively. The overall morbidity and mortality rates were 33.3 and 2.5 %, respectively. Age ≥75 years was independently associated with postoperative mortality [odds ratio (OR) 4.75, 95 % confidence interval (CI) 1.5-15.1; p = 0.008] and 1-year mortality (OR 2.8, 95 % CI 1.2-6.6; p = 0.015). The postoperative complication rate (p = 0.216) was not increased, even for major complications (p = 0.09). The other independent risk factors for mortality were a cirrhotic liver (p = 0.017), preoperative arterial chemoembolization (p = 0.001), caval vein clamping (p = 0.001), and intraoperative blood transfusion (p = 0.044).

CONCLUSIONS

Age beyond 75 years represent a risk factor of death after LR and should be avoided after chemoembolization or in cirrhotic patients. A specific assessment using geriatric indexes might be the key to success in this population.

Liver resection for colorectal metastases in older adults: a paired matched analysis

OBJECTIVES

To assess the safety and long-term results of hepatic resection of colorectal liver metastases (CLM) in older adults.

DESIGN

Case-control.

SETTING

Single liver and multivisceral transplant center.

PARTICIPANTS

Individuals with CLM: 32 aged 70 and older (older group) and 32 younger than 70 (younger group) matched in a 1:1 ratio according to sex, primary tumor site, liver metastases at diagnosis, number of metastases, maximum tumor size, infiltration of cut margin, type of hepatic resection, and hepatic resection timing.

MEASUREMENTS

Postoperative complications and survival rates.

RESULTS

There was no significant difference in preoperative clinical findings between the two study groups. The incidence of cumulative postoperative complications was similar in the older (28.1%) and younger (34.4%) groups (P = .10). One-, 3-, and 5-year disease-free survival rates were 57.6%, 32.9%, and 16.4%, respectively, in the younger group and 67.9%, 29.2%, and 19.5%, respectively, in the older group (P = .72). One-, 3-, and 5-year participant survival rates were 84.1%, 51.9%, and 33.3%, respectively, in the older group and 93.6%, 63%, and 28%, respectively, in the younger group (P = .50).

CONCLUSIONS

Resection of colorectal liver metastases in older adults can be performed with low mortality and morbidity and offers a long-time survival advantage to many of these individuals. Based on the results of this case-control study, older adults should be considered for surgical treatment whenever possible.

Safety and efficacy of hepatectomy for colorectal metastases in the elderly

BACKGROUND AND OBJECTIVES

The aim of this study was to determine the safety and efficacy of hepatic metastasectomy in elderly patients with colorectal liver metastases (CLM).

METHODS

A retrospective review of a hepatobiliary database was performed on consecutive patients treated with metastasectomy for CLM. Patients were stratified by age (<70 years old vs. ≥70). Patient and tumor characteristics as well as operative factors were compared, as were morbidity, mortality, and length of stay. Logistic regression and Cox proportional hazards were used to evaluate the association of age and postoperative outcomes.

RESULTS

There were 59 elderly (median age 75) and 220 non-elderly (median age 58) patients analyzed over a 13 year period. The Charlson comorbidity index was higher in the elderly group (mean 4.7 vs. 4.4 P = 0.005). Postoperative morbidity and mortality were 52.5 and 0% vs. 48.2 and 4.1% in the elderly and non-elderly groups, respectively (P = 0.56 and P = 0.21). There were no differences in median DFS (21.8 months vs. 28.9 months; P = 0.157) or OS (36 months vs. 47.7 months; P = 0.070) between the elderly and non-elderly groups, respectively.

CONCLUSIONS

Age itself does not appear to be a significant contraindication to liver resection, including major hepatectomy, when patients are appropriately selected.

Effect of aging on gastric mucosal defense mechanisms: ROS, apoptosis, angiogenesis, and sensory neurons

Aging changes in the stomach lead to a decreased capacity for tissue repair in response to gastric acid. The aim of this study was to determine the mechanism associated with the increased susceptibility to injury of aging mucosa including reactive oxygen species (5), apoptosis, angiogenesis, and sensory neuron activity. Fischer 344 rats at four different ages (6, 31, 74 wk, and 2 yr of age) were studied. The connective tissue indicators [salt-soluble collagen and sulfated glycosaminoglycan (sGAG)], lipid hydroperoxide (LPO), myeloperoxidase (MPO), and hexosamine were assessed. We also evaluated the expression of early growth response-1 (Egr-1), phosphatase and tension homologue deleted on chromosome 10 (PTEN), caspase-9 (index of apoptosis), VEGF (index of angiogenesis), calcitonin gene-related peptide (CGRP, index of sensory neurons), and neuronal nitric oxide synthase (nNOS). The histological connective tissue area in the lower part of rat gastric mucosa increased with aging, with increase of salt-soluble collagen and sGAG. LPO and MPO in old rats were significantly greater than in the young rats, whereas hexosamine was significantly reduced. The old gastric mucosa had increased expression of Egr-1, PTEN, and caspase-9, whereas the VEGF, CGRP, and nNOS expression were significantly reduced. These results indicate that the lower part of rat gastric mucosa was found to be replaced by connective tissue with accumulation of oxidative products with aging. In addition, impairment of apoptosis, angiogenesis, and sensory neuron activity via the activation of Egr-1 and PTEN might increase the susceptibility of gastric mucosa to injury during aging.

Major resection of hepatic colorectal liver metastases in elderly patients – An aggressive approach is justified

AIMS

With a progressively ageing population, increasing numbers of elderly patients will present with colorectal metastases and be referred for surgical resection. The aim of this study was to assess the safety of hepatic resection in patients over 70 years of age by comparing outcomes with those of a younger cohort of patients.

METHODS

Forty-nine patients over 70 years of age who underwent hepatic resection of colorectal liver metastases were compared to 142 patients less than 70 years of age in terms of pre-, peri- and post-operative results, as well as long-term survival.

RESULTS

Major resections were performed in 61% of the elderly group and 68% of the younger group. The two groups were comparable in terms of operative duration, transfusion rate, length of HDU stay and post-operative hospital stay. The elderly group had a non-significant increase in post-operative morbidity. The 30-day and 60-day/inpatient mortality rates were similar between the two groups (elderly 0% and 4%; younger 2% and 3%). Long-term disease-free survival was similar between elderly and younger patients.

CONCLUSION

This study confirms that an aggressive surgical policy towards colorectal metastases in elderly patients is associated with low peri-operative morbidity and mortality, as well as good long-term outcomes.

The impact of advanced age on hepatic resection of colorectal liver metastases

BACKGROUND

The aim of this study was to evaluate the impact of patient age on surgical therapy for colorectal liver metastases.

STUDY DESIGN

Between 1992 and 2004, 212 consecutive patients underwent potentially curative hepatic resection. Sixty-two patients were 70 years or older at the time of resection (older group) and 150 patients were less than 70 years at the time of resection (younger group).

RESULTS

A proportion of older patients had a history of severe cardiopulmonary disease (32.3%) and respiratory insufficiency (6.5%). Intraoperative variables, such as resected liver volume, operation time, estimated blood loss, and blood transfusion, were not notably different between older and younger patients. Postoperative complications after resection occurred in 19.7% of older patients and at a similar rate (23.3%) in the younger group. Resection mortality was 0% in older patients and 0.49% in younger patients. The 5-year survival rates of older and younger patients were 34.1% and 53.1%, respectively. Compared with younger patients, the overall survival rate of older patients was markedly lower (p<0.01).

CONCLUSIONS

Advanced chronologic age cannot be regarded as a medical contraindication for hepatic resection of colorectal liver metastases in patients who are more than 70 years of age.

Preliminary report on surgical technique in hepatic parenchymal transection for liver tumors in the elderly: a lesson learned from living-related liver transplantation

BACKGROUND AND OBJECTIVES

Availability of hi-tech surgical devices has elaborated the technique of parenchymal transection during hepatectomy from classic crushing clamp technique 1,2 to a combination of an ultrasonic dissection with special type of cautery 3,4. We have developed a new technique to resect hepatic parenchyma using an ultrasonic surgical aspirator in association with a monopolar floating ball. This combination has been utilized in 42 liver resections.

METHODS

A retrospective analysis of perioperative mortality, length of hospitalization, and blood transfusion during surgery in two patient groups who underwent liver resection was carried out. We divided the patient population into Group A (42 patients), who underwent the new technique, and Group B (107 patients), who experienced the crushing clamp technique. A second analysis was performed, where we divided the same patient population group in Group 1 with age less than 65, and Group 2 including patients older than 65 years.

RESULTS

We found that the new technique reduced length of stay, procedure length, and use of perioperative blood. We determined that the two age groups performed similarly in comparison to LOS, length of procedure, blood use, and complications.

CONCLUSION

This enforces the fact that the elderly can receive such surgical treatment without hesitation.

Expression of epidermal growth factor-receptor related protein (ERRP) in human colorectal carcinogenesis

We hypothesize that ERRP (EGFR-related protein), a recently identified negative regulator of EGFR may modulate EGFR function in colorectal carcinogenesis. The expression of ERRP and EGFR in normal and neoplastic colorectal tissue was examined. ERRP was highly expressed in normal colonic mucosa and benign colorectal adenomas, but lower in colorectal cancer. Mean scores for ERRP expression decreased significantly across well differentiated, moderately well differentiated and poorly differentiated (P = 0.002) tumors, respectively. ERRP expression became more attenuated in polyps with increasing grades of dysplasia. In contrast, expression of EGFR was inversely related to ERRP in representative samples of normal and neoplastic tissues.

Cardiovascular drug therapy in the elderly: theoretical and practical considerations

The elderly population is expanding rapidly throughout the world. Hypertension, heart disease and other cardiovascular disorders are prevalent conditions among this age group. Consequently, clinicians will spend a large proportion of their practices managing older adults with cardiovascular disorders. A large proportion of this time will be devoted to using pharmacotherapeutic strategies for the long-term management of chronic conditions. The physiological changes that accompany aging affect cardiovascular function, and the pharmacokinetics and pharmacodynamics of many cardiovascular medications are altered by these physiological changes. The interactions of these changes can have a profound effect on the agents used to treat cardiovascular disorders and may alter their therapeutic outcomes. Several classes of medications are used to treat chronic cardiovascular disorders in older adults. These include the ACE inhibitors and angiotensin II receptor antagonists, calcium channel antagonists, beta-adrenoceptor antagonists (beta-blockers), oral antiarrhythmic agents and warfarin. Drugs such as beta-blockers may aggravate decreased cardiac output and increase peripheral resistance, but are valuable adjuncts in many patients with congestive heart failure. Agents that reduce angiotensin II activity may have several benefits for treating heart failure and hypertension. Successful treatment of cardiovascular disorders in older adults requires the choice of the most appropriate agent, taking into consideration the complex interactions of pharmacokinetics, pharmacodynamics and disease effects.

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.

Reduction of hepatic acute phase response after partial hepatectomy in elderly patients

The hepatic capacity for acute phase protein synthesis after partial hepatectomy in the elderly patients was prospectively studied. Forty-one patients who consecutively underwent a partial hepatectomy were grouped according to age of greater or less than 70 years; 12 were in the older group and 29 in the younger. The changes in the levels of serum interleukin-6, alpha 1-antitrypsin, alpha 1-acid glycoprotein, haptoglobin, and plasma fibrinogen were measured after surgery. The postoperative changes in standard liver function tests were also measured. The incidence of postoperative infected complications was 25% in the older group and 7% in the younger (P = 0.28). Although postoperative levels of serum interleukin-6 were similar between the two groups, those of serum alpha 1-antitrypsin, alpha 1-acid glycoprotein, and haptoglobin were significantly lower in the elderly (P < 0.05). Postoperative levels of serum alpha 1-antitrypsin and plasma fibrinogen showed an increase of about 30% compared with the preoperative values (P < 0.05) in the younger group, but no significant increase in the older. Postoperative deterioration of serum albumin levels and hepaplastin test values was also significantly more severe in the older group (P < 0.05). We conclude that in the older patients, a reduction of acute phase protein synthesis occurs after partial hepatectomy as a result of a global deterioration of liver function, and may render patients liable to infection.

Elective hepatic resection in the elderly

This retrospective review assessed the safety and validity of elective liver resection in patients older than 64 years of age. In all, 293 patients underwent elective liver resection over a 23-year period (1967-1990). Fifty-two patients (18 per cent) were older than 64 (maximum 84, mean 70.4) years and all but four of these did not have cirrhosis. In this older subgroup, indications for resection were liver metastases in 30 patients, primary malignancy in 16, benign tumours in five and multiple abscesses in one. There were 21 major resections, with two deaths from hepatic failure, and 31 minor resections, with one death from cardiac failure (total mortality rate 6 per cent). During the same period, there were seven deaths after elective resections performed in 222 patients without cirrhosis who were younger than 64 years (P = 0.39). Mortality rate and duration of postoperative hospital stay were not related to the extent of liver resection nor to patients' grading according to the American Society of Anesthesiologists' criteria. Intraoperative blood loss was the only parameter found to influence mortality rate (P = 0.008) and duration of hospital stay (P = 0.04). Elective liver resection can be safely undertaken in elderly patients without cirrhosis, provided that intraoperative blood loss is minimized.

Morphological and biochemical changes in gastric mucosa of aging rats

Although previous data from this laboratory have indicated that aging is associated with increased gastric mucosal proliferative activity, no direct assessment of proliferative potential of the tissue has been made during aging. In order to assess this, and to determine whether changes in mucosal proliferative potential would be reflected in growth of the tissue, we have examined the labeling index (LI), height and morphology of the gastric mucosa in young (4-month-old) and aged (24-month-old) Fischer-344 rats. In addition, tyrosine kinase (Tyr-k) activity and the levels of phosphotyrosine proteins were determined to evaluate their relationship to mucosal proliferative activity. Histologic evaluation revealed a marked atrophy of the mucosal glandular component with 32% reduction in height in aged rats when compared with young animals. In aged rats, there was also a decrease in gland density, resulting in a reduction in the number of epithelial cells of all types with evidence of decreased secretory activity. Despite the occurrence of mucosal atrophy in aged rats, LI in these animals was significantly increased by 28%. This was associated with a parallel rise in mucosal Tyr-k activity, and a two- to threefold increase in the relative concentrations of seven phosphotyrosine membrane proteins with Mr of 120, 105, 90, 60, 55, 48 and 32 kDa. We conclude that (1) although aging is associated with increased gastric mucosal proliferative activity, this does not result in mucosal growth and that (2) Tyr-k and tyrosine phosphorylation of certain proteins play a role in the regulation of gastric mucosal cell proliferation during aging.

Effect of age on tests of intestinal and hepatic function in healthy humans

We studied intestinal function and hepatic microsomal phase I monooxygenase function in healthy, free-living subjects, aged 19-91 yr. In subjects (n = 114) given a diet including 100 g/day of fat, fecal fat in a 72-h collection did not increase with advancing age. D-Xylose excretion (n = 54) following a 25-g oral load significantly declined with increasing age, but a concomitant decline in creatinine clearance suggested a decrease in renal function rather than an absorptive defect. Furthermore, there was no evidence for an age-associated increase in bile salt deconjugation by intestinal bacteria as shown by the glycocholate breath test (n = 60). Finally, there was no evidence for a decrease in hepatic microsomal function with advancing age as measured by the aminopyrine breath test (n = 60). We conclude that digestive/absorptive and hepatic microsomal phase I monooxygenase function are well preserved in healthy humans throughout life.

Age-related changes in the pharmacokinetics and pharmacodynamics of nifedipine

1. The effects of age on the pharmacology of nifedipine were investigated in 11 young and six elderly normotensive volunteers. 2. Following 2.5 mg of nifedipine i.v. the plasma clearance of nifedipine was 348 +/- 83 (s.d.) ml min-1 in the elderly compared with 519 +/- 125 ml min-1 in the young (P less than 0.05) and the AUC in the elderly was significantly greater at 125 +/- 28 ng ml-1 h compared with 83.9 +/- 19 ng ml-1 h (P less than 0.05). The Vss was similar in both age groups. 3. Following 10 mg oral sustained release nifedipine the AUC was 281 +/- 64 ng ml-1 h in the elderly compared with 136 +/- 56 ng ml-1 h in the young (P less than 0.002) and Cmax in the elderly was significantly greater at 36.8 +/- 11.8 ng ml-1 compared with 22.3 +/- 5.8 ng ml-1 (P less than 0.05). The trend towards an increased bioavailability in elderly subjects (36%) was supported by a significantly lower nitropyridine metabolite/nifedipine ratio in the elderly. 4. Absorption rate limited kinetics of the sustained release formulation were indicated by the prolonged t1/2 compared with i.v. administration. In the elderly t1/2 (oral) was significantly greater than in the young (elderly 6.7 +/- 2.2 h, young 3.8 +/- 1.4 h, P less than 0.05). 5. Haemodynamic changes in the young were confined to a tachycardia following i.v. administration. In the elderly, supine BP fell significantly following both oral and i.v. nifedipine while the heart rate remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacogeriatrics

The elderly comprise one of the fastest growing populations in the United States. By the year 2020, an estimated 45 million will be classified as elderly. Aging is a highly variable process as declines occur in physiologic functions. Alterations in cardiovascular, renal and hepatic function have the greatest effect on drug therapy. All pharmacokinetic and pharmacodynamic variables may be altered by age. Adverse drug reactions, drug interactions and poor compliance are frequent and may further complicate drug therapy. A review of those processes that commonly influence pharmacologic response and patient compliance to drug therapy is appropriate.

Vitamin B12 (cobalamin) and folate blood levels in geriatric reference group as measured by two kits

For serum vitamin B12 levels there was little apparent difference between a geriatric healthy reference group and a hospitalized group for the total population studied; however, the hospitalized males did have an increased prevalence of values less than normal range. The frequency distribution for both sexes of the geriatric reference group gave lower range limits than manufacturer's normal range. (68-632 vs 133-708 pmol/L for Becton Dickinson, and 125-609 vs 179-930 pmol/L for Bio-Rad, using 95% non-parametric limits). For folate there was an increased incidence in values of less than normal in the hospitalized group versus the geriatric reference group, but there was no difference in the ranges calculated for the latter compared to either manufacturer's normal range derived from a younger population. Comparison of results by two manufacturers' kit methods confirmed Bio-Rad's claim to increased low-end sensitivity of standard curve in range of clinical interest.