Biological variation of methylmalonic acid in urine in spanish population.

Background-aim: Methylmalonic acid (MMA) is currently the best biomarker of functional vitamin B12 deficiency. However, for a correct interpretation of the patient's results it is necessary to know its biological variation (BV). No BV data are available for urine MMA values, as measured by mass spectrometry.

Optimization of the Diagnostic Capacity of Traditional Biomarkers in Muscle Damage and Its Use in the Diagnosis of Dermatomyositis and Polymyositis.

Background-aim: Creatine kinase (CK) and aldolase are markers traditionally used in the study of muscle damage (MD). As CK determination is more specific to muscle damage, the demand for both determinations in routine laboratory tests would entail an extra cost.

Methods: Retrospective observational study conducted between 2019-2020.