Prediction of abdominal CT body composition parameters by thoracic measurements as a new approach to detect sarcopenia in a COVID-19 cohort.

As most COVID-19 patients only receive thoracic CT scans, but body composition, which is relevant to detect sarcopenia, is determined in abdominal scans, this study aimed to investigate the relationship between thoracic and abdominal CT body composition parameters in a cohort of COVID-19 patients. This retrospective study included n = 46 SARS-CoV-2-positive patients who received CT scans of the thorax and abdomen due to severe disease progression. The subcutaneous fat area (SF), the skeletal muscle area (SMA), and the muscle radiodensity attenuation (MRA) were measured at the level of the twelfth thoracic (T12) and the third lumbar (L3) vertebra. Necessity of invasive mechanical ventilation (IMV), length of stay, or time to death (TTD) were noted. For statistics correlation, multivariable linear, logistic, and Cox regression analyses were employed. Correlation was excellent for the SF (r = 0.96) between T12 and L3, and good for the respective SMA (r = 0.80) and MRA (r = 0.82) values. With adjustment (adj.) for sex, age, and body-mass-index the variability of SF (adj. r2 = 0.93; adj. mean difference = 1.24 [95% confidence interval (95% CI) 1.02-1.45]), of the SMA (adj. r2 = 0.76; 2.59 [95% CI 1.92-3.26]), and of the MRA (adj. r2 = 0.67; 0.67 [95% CI 0.45-0.88]) at L3 was well explained by the respective values at T12. There was no relevant influence of the SF, MRA, or SMA on the clinical outcome. If only thoracic CT scans are available, CT body composition values at T12 can be used to predict abdominal fat and muscle parameters, by which sarcopenia and obesity can be assessed.

[Microbiota and multiple sclerosis]. / Mikrobiota und Multiple Sklerose.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system driven by autoreactive lymphocytes. Due to its close contact with the gut-associated lymphoid tissue, the intestinal microbiota and/or their metabolites may be one of the factors that influence the activation of autoreactive lymphocytes. This article summarizes and discusses the current research efforts to characterize the microbiome of MS patients using human material. In addition, we present research studies that utilized classical or humanized animal models to determine the influence of certain microbiota species or compositions of microbiota on the immune system and disease progression and to define possible causal associations.

Nutritional evaluation of the legume Macrotyloma axillare using in vitro and in vivo bioassays in sheep.

This study consisted of two experiments with the following objectives: to evaluate the effects of tannins from the tropical legume macrotiloma (Macrotyloma axillare) on total gas and methane (CH4 ) production, as well as on ruminal fermentation parameters by performing an in vitro bioassay, with samples incubated with and without polyethylene glycol (PEG) in a semi-automatic system; and secondly in a 17 day in vivo experiment, to determine apparent total tract digestibility (ATTD) of dietary nutrients and ruminal fermentation parameters of 12 intact 8- to 9-month-old Santa Inês (averaging 24.95 ± 1.8 kg body weight) ewes fed tropical grass hay supplemented with macrotiloma hay. The ewes were divided into two treatment groups depending on their diet: chopped aruana grass hay (Panicum maximum cv. Aruana) (control-CON); and aruana grass hay supplemented with chopped macrotiloma hay (macrotiloma-MAC). The animals were kept for 5 consecutive days in metabolic cages for the ATTD assay, and at the end of this period, samples of rumen fluid were collected from each ewe to determine ammoniacal nitrogen (NH3 -N) and short-chain fatty acid (SCFA) production, and protozoa count. For the in vitro assay, a decrease in total gas and CH4 production was observed for samples incubated without PEG (p < .05). No differences were observed for the other parameters evaluated (p > .05). In the in vivo experiment, increased intake and ATTD of crude protein were observed for the animals fed MAC when compared to CON (p < .05). For rumen fermentation parameters, increased NH3 -N, total SCFA and isobutyrate concentrations, as well as reduced protozoa count were observed for MAC when compared to CON (p < .05). The results observed here indicated the potential of macrotiloma for use as a ruminant feed, and antimethanogenic potential of this plant was noted.

Investigation of sex-specific effects of apolipoprotein E on severity of EAE and MS.

BACKGROUND: Despite pleiotropic immunomodulatory effects of apolipoprotein E (apoE) in vitro, its effects on the clinical course of experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS) are still controversial. As sex hormones modify immunomodulatory apoE functions, they may explain contentious findings. This study aimed to investigate sex-specific effects of apoE on disease course of EAE and MS. METHODS: MOG(35-55) induced EAE in female and male apoE-deficient mice was assessed clinically and histopathologically. apoE expression was investigated by qPCR. The association of the MS severity score (MSSS) and APOE rs429358 and rs7412 was assessed across 3237 MS patients using linear regression analyses. RESULTS: EAE disease course was slightly attenuated in male apoE-deficient (apoE (-/-) ) mice compared to wildtype mice (cumulative median score: apoE (-/-) = 2 [IQR 0.0-4.5]; wildtype = 4 [IQR 1.0-5.0]; n = 10 each group, p = 0.0002). In contrast, EAE was more severe in female apoE (-/-) mice compared to wildtype mice (cumulative median score: apoE (-/-) = 3 [IQR 2.0-4.5]; wildtype = 3 [IQR 0.0-4.0]; n = 10, p = 0.003). In wildtype animals, apoE expression during the chronic EAE phase was increased in both females and males (in comparison to naïve animals; p < 0.001). However, in MS, we did not observe a significant association between MSSS and rs429358 or rs7412, neither in the overall analyses nor upon stratification for sex. CONCLUSIONS: apoE exerts moderate sex-specific effects on EAE severity. However, the results in the apoE knock-out model are not comparable to effects of polymorphic variants in the human APOE gene, thus pinpointing the challenge of translating findings from the EAE model to the human disease.

Familial Mediterranean fever-associated mutation pyrin E148Q as a potential risk factor for multiple sclerosis.

BACKGROUND: Familial Mediterranean fever (FMF) is an inherited autoinflammatory disease caused by mutations in the MEFV gene and characterized by recurrent febrile polyserositis. A possible association of FMF and multiple sclerosis (MS) has been suggested in cohorts from Turkey and Israel. OBJECTIVE: The objective of this study was to investigate the prevalence of MEFV mutations in subjects with MS and in controls in Germany. METHODS: One-hundred and fifty seven MS patients with at least one symptom or without symptoms suggestive of FMF from our outpatient clinic were investigated for mutations in exons 2, 3, and 10 of the MEFV gene (group 1). 260 independent MS patients (group 2) and 400 unrelated Caucasian controls (group 3) were screened selectively for the low-penetrance pyrin mutations E148Q and K695R RESULTS: In group 1, 19 MS patients (12.1%) tested positive for a mutation in the MEFV gene, mainly the E148Q (n=7) substitution. Fifteen of the 19 mutation-positive individuals reported at least one symptom suggestive of FMF. In three cases, we could identify additional family members with MS. In these pedigrees, the E148Q exchange co-segregated with MS (p=0.026). Frequencies of the pyrin E148Q and K695R mutations were not statistically different between MS group 2 and controls but they occurred with a surprisingly high frequency in the German population. CONCLUSION: The MEFV gene appears to be another immunologically relevant gene locus which contributes to MS susceptibility. In particular, the pyrin E148Q mutation, which co-segregated with disease in three MS families, is a promising candidate risk factor for MS that should be further explored in larger studies.

Meta-analysis on anxiety and depression in adult celiac disease.

OBJECTIVE: We used meta-analysis to test hypotheses concerning whether adult celiac disease is reliably linked with anxiety and/or depression. METHOD: We examined published reports on anxiety and depression in adult celiac disease. RESULTS: Eighteen studies on depression and eleven studies on anxiety in adult celiac disease met selection criteria. They show that depression is reliably more common and/or more severe in adults with celiac disease than in healthy adults (overall meta-analysis effect size: 0.97). The fail-safe margin of unpublished reports that would be required to negate the finding exceeds 8000. Adults with celiac disease do not, however, differ reliably in terms of depression from adults with other physical illnesses, nor do they differ reliably from healthy adults or adults with other physical illnesses in terms of anxiety. CONCLUSION: Depression is common in adult celiac disease and resembles the condition in other physical illnesses. We view the findings as support for the notion that non-specific mechanisms mediate emotional disorders in adult celiac disease.

Long-term follow-up of patients with neuromyelitis optica after repeated therapy with rituximab.

BACKGROUND: Neuromyelitis optica (NMO) is a severe autoimmune disease targeting optic nerves and spinal cord. The monoclonal anti-CD20 B-cell antibody rituximab is an emerging therapeutic option in NMO. However, neither long-term efficacy or safety of rituximab, nor the correlation between B-cell counts, B-cell fostering cytokines, aquaporin-4 antibodies (AQP4-ab), and disease activity in NMO, have been investigated prospectively. METHODS: We performed a prospective long-term cohort study of 10 patients with NMO who were treated up to 5 times with rituximab as a second-line therapy. Clinical examinations, B-cell counts, and serum concentrations of BAFF (B-cell activating factor of the TNF family; also called TNFSF13b), APRIL (a proliferation-inducing ligand; also called TNFSF13), AQP4-ab, and immunoglobulin levels were measured every 3 months. RESULTS: Repeated treatment with rituximab led to sustained clinical stabilization in most patients with NMO. Disease activity correlated with B-cell depletion, but not clearly with AQP4-ab or levels of APRIL. BAFF levels increased after application of rituximab and indicated persisting efficacy of the drug but did not correlate with disease activity. Overall, rituximab was well-tolerated even after up to 5 consecutive treatment courses; however, we observed several severe adverse reactions. CONCLUSION: Our data indicate that long-term therapy with rituximab is effective in NMO as a second-line therapy and has an acceptable safety profile. Retreatment with rituximab should be applied before reappearance of circulating B cells. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that repeated doses of rituximab result in stabilization in most patients.

Drug-induced Sweet's syndrome after mitoxantrone therapy in a patient with multiple sclerosis.

We report a 55-year-old male patient with secondary progressive multiple sclerosis who developed an acute febrile syndrome with fever, neutrophilia and tender erythematous plaques and papules on his upper extremities after his fifth mitoxantrone infusion. Infectious, haematological and rheumatological diseases were ruled out, but skin biopsy showed neutrophilic infiltrations in the dermis consistent with Sweet's syndrome. Treatment with oral corticosteroids led to prompt improvement of systemic and cutaneous symptoms. To our knowledge, this is the first report of a patient with Sweet's syndrome after mitoxantrone therapy. Clinicians should be aware of Sweet's syndrome in patients with otherwise unexplained acute febrile illness and erythematous skin rash in association with mitoxantrone therapy. Skin biopsy helped to exclude other diseases and confirmed Sweet's syndrome.

Trends in lifestyle coronary risk factors in the Danish MONICA population 1982-1992.

Myocardial infarction incidence rate declined 3-5% per year during 1982-1992 in the Danish study population of the WHO MONICA Project. We examined whether smoking habits, alcohol intake, dietary habits and physical activity levels changed in the population during the same period. Data from 6695 men and women of ages 30, 40, 50 and 60 y, examined in 1982-4, in 1986-7, and in 1991-2, were analysed to estimate trends. A summary healthy eating index and six scores derived by factor analysis were used to analyse food frequency data. The percentage of smokers declined 1.6% per year in men, and 1.0% per year in 30-, 40- and 50-y-old women, but increased 0.9% per year in 60-y-old women. The percentages of heavy cigarette smoking men and women nevertheless remained constant and close to 30%. Total alcohol intake declined among 30-y-olds, but appeared constant in other age groups. However, among 60-y-old men and among women over 30, the percentage of wine-drinkers rose from 6-11% in 1982-4 to 9-18% in 1991-2. Only 60-y-old men became more physically active at work and only 30-y-old women more so in leisure times. The percentage of individuals with a low healthy eating index decreased and the percentage with a high index increased. More importantly, dietary factor scores showed trends suggesting that very profound and potentially beneficial changes in dietary habits occurred. Lifestyle in the DAN-MONICA population changed in several ways that may have contributed to the declining incidence of myocardial infarction during the 1980s.

Survival and cause of death after myocardial infarction: the Danish MONICA study.

As part of the Danish WHO MONICA study, a register of patients with myocardial infarction was established in 1982, covering 11 municipalities in the western part of Copenhagen County, Denmark. During the period 1982-91, all cases of myocardial infarction among citizens aged 25-74 years were registered and validated according to the criteria set up for the WHO MONICA project. Short-term (28 days) and long-term (up to 15 years) survival in three periods were compared. The rate of mortality after a non-fatal myocardial infarction was compared with that of the general population, and causes of death were analyzed. Short-term survival did not change during the study period, whereas long-term survival improved for men but did not change for women. The excess mortality rate among female patients over that of the general population was due to ischemic heart disease, other cardiovascular diseases, cancer and other diseases. The excess mortality among male patients was due only to cardiovascular diseases.

Regional and hormone-dependent effects of apolipoprotein E genotype on changes in bone mineral in perimenopausal women.

We studied 479 perimenopausal Danish women aged 45-58 years to examine differences between APOE genotypes with respect to (1) baseline total body bone mineral density (BMD) and densities measured in five different regions (ultradistal forearm, proximal forearm, lumbar spine, femoral neck, and total hip region); (2) serum levels of alkaline phosphatase, bone isoenzyme alkaline phosphatase, osteocalcin, parathyroid hormone (PTH), 25-hydroxyvitamin D, and urine hydroxyproline/creatinine excretion ratio; and (3) changes in bone mineral during 5 years of follow-up. Baseline BMDs were identical, whereas serum levels of alkaline phosphatase and its bone isoenzyme were higher in women with APOE 2-2 and APOE 2-3 than in women with APOE 3-3 and APOE 3-4 and lower in women with APOE 4-4. Among women not receiving hormonal-replacement therapy (HRT; n = 262), those with APOE 2-2 and APOE 2-3 had 30-40% lower rates of femoral neck and total hip bone mineral loss than women with APOE 3-3 and APOE 3-4, whereas the rates of mineral loss in other skeletal regions did not differ between these APOE genotypes. Women with APOE 4-4 appeared to have lower rates of bone mineral loss in all regions. Women treated with hormones throughout the follow-up period (n = 113) gained bone mineral, and women with APOE 3-4 and APOE 4-4 gained relatively more mineral than other women. A comparison of untreated and treated women with APOE 2-3, APOE 3-3, and APOE 3-4 suggests a possible modification of the effect of APOE genotype by HRT. In conclusion, the common APOE polymorphism has a complex effect on bone metabolism in perimenopausal Danish women including possible modification by hormone use: (1) among women not receiving HRT, those with APOE*2 have lower bone mineral losses in the femoral neck and hip region than other women, and (2) among women receiving HRT, those with APOE*4 gain more bone mineral than other women.

Dietary patterns and mortality in Danish men and women: a prospective observational study.

The analysis of dietary patterns emerged recently as a possible approach to examining diet-disease relation. We analysed the risk of all-cause and cardiovascular mortality associated with dietary patterns in men and women, while taking a number of potential confounding variables into account. Data were from a prospective cohort study with follow-up of total and cause-specific mortality. A random sample of 3698 men and 3618 women aged 30-70 years and living in Copenhagen County, Denmark, were followed from 1982 to 1998 (median 15 years). Three dietary patterns were identified from a twenty-eight item food frequency questionnaire, collected at baseline: (1) a predefined healthy food index, which reflected daily intakes of fruits, vegetables and wholemeal bread, (2) a prudent and (3) a Western dietary pattern derived by principal component analysis. The prudent pattern was positively associated with frequent intake of wholemeal bread, fruits and vegetables, whereas the Western was characterized by frequent intakes of meat products, potatoes, white bread, butter and lard. Among participants with complete information on all variables, 398 men and 231 women died during follow-up. The healthy food index was associated with reduced all-cause mortality in both men and women, but the relations were attenuated after adjustment for smoking, physical activity, educational level, BMI, and alcohol intake. The prudent pattern was inversely associated with all-cause and cardiovascular mortality after controlling for confounding variables. The Western pattern was not significantly associated with mortality. This study partly supports the assumption that overall dietary patterns can predict mortality, and that the dietary pattern associated with the lowest risk is the one which is in accordance with the current recommendations for a prudent diet.

Trends in incidence, case-fatality and recurrence of myocardial infarction in the Danish MONICA population 1982-1991.

BACKGROUND: Growing awareness of risk factors for myocardial infarction (MI), continuous mass campaigns on lifestyle factors, increasing use of heart rehabilitation and improved treatment should imply decreases in the incidence, case-fatality and recurrence rates of MI. The purpose of the study was to assess trends in the incidence, case-fatality and recurrence rate of MI and to analyse whether any changes seen were due to a period or a cohort effect. METHODS: The Danish MONICA population comprises all men and women aged 25-74 years in the period 1982-1991 living in a suburban area of Copenhagen, Denmark. Fatal and non-fatal attacks classified as definite MI and non-fatal attacks classified as possible MI were included. The incidence rate was analysed by Poisson regression, the case-fatality rate by logistic regression, and the rate of recurrence by Cox regression. Age-period-cohort analyses were carried out according to a method described by Clayton and Schifflers. RESULTS: During the 10-year period a significant decrease in the incidence rate of MI was seen for men and women and for the rate of recurrent MI. The decrease in incidence and recurrence could not unambiguously be ascribed to a period or cohort effect. The rate of case-fatality after a first MI was not changed significantly during the period, whereas men and women had different trends in case-fatality after recurrent MI. CONCLUSIONS: In accordance with results from other Western countries we found a decline in the incidence and recurrence rate of MI. Contrary, the lack of a decrease in the case-fatality rate after a first MI was unexpected and difficult to explain.

[Trends in selected biological risk factors of cardiovascular diseases in the Danish MONICA population 1982-1992]. / Udviklingen i udvalgte biologiske risikofaktorer for kardiovaskulaere sygdomme i den danske MONICA-population 1982-1992.

INTRODUCTION: The incidence rate of a first myocardial infarction declined 3-5% annually in the Danish WHO MONICA population in the period from 1982 to 1991. The aim of this study was to investigate whether levels of the most commonly considered biological traits associated with cardiovascular risk have changed in the Danish MONICA population during this period. METHOD: Data from 6,695 men and women of 30, 40, 50 and 60 years of age, examined in the Danish WHO MONICA surveys in 1982-1984, 1986-1987, and 1991-1992, were analysed to estimate temporal trends in body height and weight, blood pressure, and serum total, HDL, and LDL cholesterol, and triglyceride. RESULTS: Body height increased by 0.1% per year and the body mass index by 0.4% per year in women. The diastolic blood pressure increased 0.4% per year in women and 0.6% per year in 60-year-old men. HDL cholesterol declined 0.4% per year. Body mass indices in men, diastolic blood pressures in men < 60 years of age, systolic blood pressures, total and LDL cholesterol and triglyceride did not change. DISCUSSION: The levels of biological risk factors in the Danish WHO MONICA study population did not show trends during the 1980s that contribute to explain the declining incidence of myocardial infarction in the population.

Estimation of apolipoprotein E genotype-specific relative mortality risks from the distribution of genotypes in centenarians and middle-aged men: apolipoprotein E gene is a "frailty gene," not a "longevity gene".

We developed a method to estimate genotype-specific average relative mortality risk, R, from genotype distributions in cross-sectional studies of people belonging to different age-groups, and applied the method to new data from a study of apolipoprotein E genotypes (apoE) in 177 Danish centenarians and data from a study of 40-year-old Danish men. Twenty-one percent of the centenarians were epsilon 2-carriers (genotypes epsilon 2 epsilon 2 and epsilon 3 epsilon 2) and 15% were epsilon 4-carriers (genotypes epsilon 4 epsilon 4 and epsilon 4 epsilon 3) compared to 13 and 29%, respectively, of the young men. The R-values were 0.95 (95% CI 0.88 to 1.02) for epsilon 2-carriers and 1.13 (95% CI 1.05 to 1.22) for epsilon 4-carriers, using epsilon 3 epsilon 3- and epsilon 4 epsilon 2 genotypes as reference. Corresponding values for epsilon 4-carriers were obtained by using published data from a French and a Finnish study of centenarians, whereas the values for epsilon 2-carriers were about 0.90 with these data. The method to estimate mortality risk and the results associate with the view that the apoE gene is a "frailty gene." On the other hand, if odds ratios are used to summarize data from studies of this kind, they are more impressive and may propagate the misconception that apoE is a "longevity gene".

Apolipoprotein E genotype is associated with differential expansion rates of small abdominal aortic aneurysms.

BACKGROUND: The common polymorphism of the apolipoprotein E (APOE) gene is associated with differential risk of atherosclerosis; the gene could be a candidate gene in abdominal aortic aneurysms (AAA). METHODS: APOE genotypes were determined in 57 men aged 65-73 years with a small AAA (30-50 mm). The patients were included in a population ultrasonographic screening programme and were followed with at least two examinations during an interval of 2-4.5 years. The AAA expansion rates in patients with four different APOE genotypes were studied, with adjustment for initial AAA size and smoking. RESULTS: APOE genotype was a significant determinant of AAA expansion rate (P = 0.001). The adjusted mean (95 per cent confidence interval) rate was 2.1 (1.7-2.6) mm/year in 31 men with genotype E3E3, 1.3 (0.7-1.9) mm/year in 17 men with E3E4, 3.1 (2.0-4. 1) mm/year in six men with E2E3 and 4.2 (2.7-5.6) mm/year in three men with E2E4. The mean expansion rate was 2.2 (1.5-2.8) mm/year in non-smokers and 3.0 (2.5-3.6) mm/year in smokers (P = 0.014). CONCLUSION: APOE genotype seems to influence AAA expansion rate, but the effects of the individual genotypes, in particular E3E3 and E3E4, are contradictory when compared with the effects of the genotypes on risk of atherosclerosis.

Association of coronary heart disease with age-adjusted aortocoronary calcification in patients with familial hypercholesterolaemia.

OBJECTIVES: Existing algorithms of risk of coronary heart disease (CHD) do not pertain to patients with familial hypercholesterolaemia (FH), whose arteries have been exposed to hypercholesterolaemia since birth. We studied a cohort of FH patients to compare four diagnostic models of CHD: traditional risk factors of CHD (age, sex, cholesterol, hypertension, smoking and body mass index), cholesterol year score, and aortic as well as coronary calcium measured by spiral computed tomography (CT). SUBJECTS: We invited 88 individuals with molecularly defined FH of whom 80 (91%) decided to participate. RESULTS: Analysis of receiver operating characteristic curves showed that the age-adjusted coronary calcium score was more strongly associated with clinical manifestations of CHD than were traditional risk factors (P < 0.002), cholesterol year score (P << 0.0001), and the age-adjusted aortic calcium score (P < 0.0004). CONCLUSIONS: Age-adjusted coronary calcium score shows promise as an indicator of CHD in FH patients.

The marker of cobalamin deficiency, plasma methylmalonic acid, correlates to plasma creatinine.

OBJECTIVE: To examine the relationship between the two diagnostic tests, plasma methylmalonic acid and plasma cobalamins, and their association with plasma creatinine, age and sex. DESIGN: Cross-sectional study of simultaneous laboratory measurements. SETTING: County of Aarhus, Denmark. SUBJECTS: Records on 1689 patients who had their first plasma methylmalonic acid measurement during 1995 and 1996, and who had a simultaneous measurement of plasma cobalamins. Plasma creatinine values measured within a week of measurements of plasma methylmalonic acid and plasma cobalamins were available for 1255 of the patients. MAIN OUTCOME MEASURES: Predictors of variation in plasma methylmalonic acid; plasma cobalamins, plasma creatinine, age and sex. RESULTS: Plasma methylmalonic acid was positively correlated with plasma creatinine, even for plasma creatinine within the normal range. These associations remained in a multiple regression analysis. For plasma cobalamins below 200 pmol L-1, there was a strong negative correlation between plasma methylmalonic acid and plasma cobalamins, whilst the association was weak for higher plasma cobalamin levels. Plasma methylmalonic acid increased and plasma cobalamins decreased with age. CONCLUSIONS: The strong correlation between plasma methylmalonic acid and plasma creatinine suggests that plasma creatinine - also within the normal range - must be taken into consideration when interpreting plasma methylmalonic acid.

Physicians' use of plasma methylmalonic acid as a diagnostic tool.

OBJECTIVES: To investigate physicians' reasons for requesting plasma methylmalonic acid and their reactions to an increased concentration of plasma methylmalonic acid. DESIGN: Study of medical records. SETTING: Three somatic district hospitals in Denmark. SUBJECTS: Medical records of 198 patients with a plasma methylmalonic acid measurement above the reference interval. Information on diagnostic decisions was available for 177 patients. MAIN OUTCOME MEASURES: Reasons for requesting plasma methylmalonic acid and the reactions to the finding of elevated plasma methylmalonic acid. RESULTS: An explicit reason for requesting plasma methylmalonic acid was stated in 57% of 198 examined medical records, known or suspected anaemia being the most frequent reason. No further action was taken in 109 (62%) of the 177 cases available for follow-up. Amongst the remaining 68 patients, the finding of an increased plasma methylmalonic acid led to diagnosis of cobalamin deficiency in 46 patients. Six patients with a markedly increased plasma methylmalonic acid (above 0.99 micromol L-1) and clearly decreased plasma cobalamins (below 200 pmol L-1) were not recognized as having cobalamin deficiency. CONCLUSIONS: This lack of response to an increased plasma methylmalonic acid raises an important question. Is the clinical response inadequate, or is the connection between an increased level of plasma methylmalonic acid and signs of clinical significant cobalamin deficiency less clear?