Serotonin and 5-hydroxyindole-acetic acid

Abstract

Background: In patients suffering from chronic renal insufficiency (CRI) serotonin (5HT) metabolism is impaired, and plasma 5-hydroxyindoleacetic acid (5HIAA) levels (main metabolite of 5HT) are increased.

Aim: In this study we aimed to give a detailed description of peripheral serotonin metabolism in healthy subjects and patients with CRI, and to evaluate the efficacy of hemodialysis in the elimination of cumulated 5HT and 5HIAA.

Methods: 5HT (platelet rich plasma, platelet poor plasma, urine, HPLC with electrochemical detection) and 5HIAA (plasma, urine, HPCL with electrochemical detection) levels were evaluated in 14 conservatively treated (CT) and 12 hemodialysed (HD) patients with CRI and were compared to those of 60 healthy volunteers (HV).

Results: In patients with CRI accumulation of 5HT and 5HIAA in plasma with no changes in platelet 5HT content was revealed. 5HT renal and fractional excretion (FE) was markedly decreased in CRI. FE-5HT was < 1 in all investigated subjects, indicating its reabsorption in proximal tubules, or local degradation to 5HIAA. Due to the increased filtration load renal excretion of 5HIAA was not altered in CT patients, however it was decreased in HD patients. The relative participation of glomerular filtration in 5HIAA renal excretion increased in CRI. FE-5HIAA > 5 was found in 20% of HV and 15% of CT, pointing indirectly to 5HIAA intrarenal production. In CRI FE-5HIAA decreased. HD did not eliminate accumulated 5HT and 5HIAA effectively.

Conclusion: Increased levels of 5HT and 5HIAA might exert metabolic effects contributing to the clinically manifested impairments characteristic for uremic syndrome. (Tab. 3, Fig. 3, Ref. 27.)