Increased levels of what is a hallmark sign of Pyridoxine (B6) deficiency?

Increased levels of homocysteine are a hallmark sign of pyridoxine (vitamin B6) deficiency due to its critical role as a cofactor in the transsulfuration pathway, which helps in the metabolism of amino acids. Specifically, pyridoxine is involved in the conversion of homocysteine to cysteine, a reaction that is catalyzed by the enzyme cystathionine beta-synthase. When there is a deficiency of vitamin B6, the conversion process is impaired, leading to the accumulation of homocysteine in the bloodstream.

Elevated homocysteine levels are associated with various health issues, including cardiovascular diseases, because they may contribute to endothelial dysfunction and promote atherogenesis. Monitoring homocysteine levels can thus be a valuable indicator of pyridoxine status and overall metabolic health.

The other choices, such as methylmalonic acid, ketone bodies, and beta-hydroxybutyrate, are more closely associated with deficiencies of other vitamins or metabolic states rather than specifically highlighting a deficiency of vitamin B6. Thus, homocysteine stands out as a key biomarker for understanding the impact of pyridoxine deficiency.