Serum Transcobalamin Concentration in Cats-Method Validation and Evaluation in Chronic Enteropathies and Other Conditions.

Hypocobalaminemia is common in cats with chronic enteropathy (FCE). However, the disruptions in cobalamin metabolism are not fully understood and may vary across species. Cobalamin is distributed to target tissues via binding to transcobalamin (TC) in blood, which has not been evaluated in cats.

Heterozygous Mutations in Both the and Genes: Double Haploinsufficiency as an Unusual Cause of Vitamin B Deficiency-A Case Report.

Vitamin B deficiency is usually simple to diagnose. However, our patient demonstrates that in difficult cases, the ordinary clinician may need a transdisciplinary approach. The finding of a double haploinsufficiency as a possible cause of vitamin B deficiency in our patient, illustrates the usefulness of performing large panel clinical exome sequencing.

Vitamin B12-Related Biomarkers.

Background: Adult vitamin B12 (B12) deficiency may present itself with nonspecific mainly neurological symptoms, and thus plasma biomarkers are often judged to be of major importance in the further diagnostic process. Four biomarkers are of special relevance: total B12, holotranscobalamin (the part of B12 bound to the active transport protein, transcobalamin, also named holoTC or active B12) and the 2 so-called metabolic markers that accumulate if B12 is lacking, methylmalonic acid (MMA) and homocysteine.

Objective: This article briefly reviews the inherent limitation of biomarkers, discusses its use in establishing the diagnosis and cause of B12 deficiency, and when following or discontinuing treatment with B12.

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No international treatment standard for B12 deficiency exists. Current practice predominantly relies on more than 50 years old data. Consequently, this review investigates that we still recommend five injections with 1 mg B12 over 10 days followed by maintenance therapy with 1 mg oral B12 daily or injections, of which the interval is guided by symptom relief rather than normalization of biomarkers.

Macro-B12 and Unexpectedly High Levels of Plasma B12: A Critical Review.

A low total plasma vitamin B12 supports a clinical suspicion of B12 deficiency, while the interpretation of an unexpectedly normal/high level is marred by controversies. Here, we critically review current knowledge on B12 in blood plasma, including the presence of the so-called "macro-B12". The latter form is most often defined as the fraction of B12 that can be removed by precipitation with polyethylene glycol (PEG), a nonspecific procedure that also removes protein polymers and antibody-bound analytes.