Excretion

Less than 1% of absorbed riboflavin is eliminated with bile. About half can be recovered as riboflavin or known riboflav in metabolites from urine (Zempleni etai. 1996). The remainder leaves the body by as yet unknown pathways (Zempleni et al., 1996). The ponton of riboflavin and its various circulating metabolites that is not bound to albumin or other proteins readily passes into primary filtrate in the renal glomerulus and depends for reuptake 111 the proximal renal tubule on sodium-independent, carrier-mediated transport (Kumar eta!., 199X). In addition, riboflavin is secreted into the tubular lumen. At high intakes the secreted amount far exceeds the reabsorbed amount. Less than a third of ingested riboflavin al normal intake levels is excreted with urine (Zempleni el al„ I99fi). Urine normally contains mainly riboflavin (60-70%), and much smaller amounts of 7-hydrom ethyl riboflavin (10 15%), 8-hydromelhylriboilavin (4 7%). and X-alpha-su! tony I riboflavin (Chastain and McCormick. 19X7; McCormick. 1994).

Riboflavin O

Riboflavin O

8-..-Hydroxy methyl riboflavin

8-..-Hydroxy methyl riboflavin

7-«-Hydroxy methyl riboflavin

HO-S-OH

HO-S-OH

8-ii-Sultonyl riboflavin

Figur« 10.15 Major urinary metabolrtes related to riboflavin ingestion

8-ii-Sultonyl riboflavin

Figur« 10.15 Major urinary metabolrtes related to riboflavin ingestion

Regulation

Several hormones, including triiodothyronine. At 111, and aldosterone tightly control FMN synthesis by enhancing riboflavin kinase activity, FMN synthesis declines in severe malnutrition, apparently due to diminished triiodothyronine production (Capo-chichi et ai, 2000).

Understanding And Treating Autism

Understanding And Treating Autism

Whenever a doctor informs the parents that their child is suffering with Autism, the first & foremost question that is thrown over him is - How did it happen? How did my child get this disease? Well, there is no definite answer to what are the exact causes of Autism.

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