No abstract

IntroductionWhile cobalamin (Cbl) deficiency classically causes macrocytic anemia, anemia can occur without macrocytosis, and both neurologic and cognitive dysfunction often develop in the absence of hematologic changes. 1-5 Symptoms consistent with Cbl deficiency, including paresthesias, unsteady gait, fatigue, and impaired memory, are commonly encountered in the ambulatory care setting, and early recognition of Cbl deficiency is important to prevent progressive, irreversible neurologic and cognitive impairment. 6,7 Although treatment with Cbl is often initiated after the finding of a low serum Cbl level, many patients with low Cbl levels are not Cbl deficient. 8,9 As a result, measurements of the Cbl-dependent metabolites, methylmalonic acid (MMA) and homocysteine (HCys), have recently been used to confirm the presence of Cbl deficiency. Retrospective studies of patients at academic medical centers with low serum Cbl levels and clinically overt Cbl deficiency found MMA and/or HCys levels more than 3 standard deviations (SD) above the normal mean in almost all patients. 8,10-12 Thus, algorithms for the diagnosis of Cbl deficiency were developed that suggest initial measurement of serum Cbl followed by determination of MMA and HCys when Cbl levels are intermediate or when suspicion of clinically significant Cbl deficiency is high. 8,[13][14][15][16][17][18][19][20] However, because little attention has been given to the study of patients with clinical findings consistent with Cbl deficiency but normal vitamin and metabolite levels, the negative predictive value of these tests is uncertain. Indeed, Cbl levels are normal in some patients with overt deficiency, 11 and currently available Cbl assay kits may not be reliable. 21,22 Moreover, because studies from academic centers usually employed special diagnostic or research laboratory facilities, their findings may not be representative of those obtainable in other ambulatory care settings.Thus, a retrospective review of patients evaluated for Cbl deficiency during a 10-year period at a staff model HMO utilizing a national commercial laboratory was performed. Initially, only patients with low serum Cbl levels or elevated metabolite levels received therapeutic trials of Cbl. However, in the seventh year of the study period, one patient with total absence of vibratory sensation in the iliac crest, knees, and ankles had complete recovery following 2 months of Cbl therapy despite normal Cbl, MMA, and HCys levels. Thereafter, therapy was offered to all patients with hematologic or neurologic abnormalities consistent with Cbl deficiency regardless of the results of screening studies. Patients, materials, and methods Laboratory methodsSerum Cbl was measured by the ADVIA Centaur chemiluminescence assay (Bayer Diagnostics, Tarrytown, NY). Normal Cbl values were 200 to 1100 pg/mL, but higher reference ranges have been suggested, 11,13,16,17,20,23,24 and the statement "patients with values less than 300 pg/mL may experience unexplained neuropsychiatric or hematologic abnormali...

Up to 46% of patients with NAFLD may have thrombotic risk factors, and the presence of thrombotic risk factors is correlated with the extent of hepatic fibrosis, suggesting a crucial role of the coagulation system in the pathogenesis of hepatic fibrosis.

OBJECTIVEFunctional cobalamin (Cbl) deficiency (i.e., high methylmalonic acid [MMA] values despite normal serum Cbl levels) is common in the elderly and associated with neuropathy and anemia. Because diabetes is also common in the elderly and diabetic neuropathy resembles that of Cbl deficiency, the role of diabetes in functional Cbl deficiency was explored.RESEARCH DESIGN AND METHODSA retrospective review was performed of all ambulatory community-dwelling adults with normal renal function evaluated for Cbl deficiency over a 12-year period in a primary care setting. Functional Cbl deficiency was defined as MMA values >250 nmol/L with Cbl levels >400 pg/mL.RESULTSIn nondiabetic subjects, MMA values varied directly with age and inversely with serum Cbl. In diabetic subjects, MMA values also increased with age but did not fall as Cbl levels increased. Thus, when Cbl levels were >400 pg/mL, mean MMA values and the incidence of functional Cbl deficiency were both significantly greater in elderly diabetic subjects (at least 70 years old) than in elderly nondiabetic subjects. Moreover, neuropathy was present in 62% of diabetic subjects with high MMA values and in only 18% of diabetic subjects with normal MMA values. Finally, pharmacologic doses of Cbl improved MMA values and neuropathy in 88 and 86% of evaluable diabetic subjects, respectively.CONCLUSIONSThese observations suggest that functional Cbl deficiency is common in elderly diabetic individuals, is associated with neuropathy, and is responsive to Cbl therapy. A role for oxidative stress in the pathogenesis of functional Cbl deficiency is proposed.

Pain due to vaso-occlusive crisis is the major cause of hospital use in sickle cell disease. Although available guidelines provide recommendations for opioid administration in this setting, only 4 (21%) of 19 medical textbooks present treatment regimens that are consistent with them. Moreover, only 7 texts (37%) note that addiction is infrequent in this population, while 11 (92%) of 12 texts provide such reassurance for cancer-related pain (P < .005). Finally, hydroxyurea use to decrease the frequency of vasoocclusive crises is completely defined only in 2 textbooks. Thus, most medical texts provide neither adequate information for the treatment or prevention of pain due to vaso-occlusive crisis in sickle cell disease nor reassurance of the unlikelihood of addiction in this population. In contrast, treatment recommendations for less common hematologic disorders are consistent with current standards in 53% to 84% of appropriate texts (P < .05). Limited knowledge regarding the principles and appropriateness of opioid therapy; a lack of evidence-based research on pain control; and misconceptions and prejudices about drug abuse and addiction contribute to this educational void. Thus, research and training on pain control in sickle cell disease are needed to parallel studies of environmental and genetic factors contributing to the known clinical heterogeneity of this disorder. (Blood. 2008;111:997-1003)