Effect of amino acid infusion on potassium serum levels in neuroendocrine tumour patients treated with targeted radiopeptide therapy

Purpose: Administration of positively charged amino acids has been introduced to reduce the nephrotoxicity of targeted radiopeptide therapy (TRT). However, the amino acid solution may have side effects, including hyperkalaemia. The aim of this study was to evaluate the frequency and the magnitude of hyperkalaemia in neuroendocrine tumour (NET) patients undergoing TRT. Methods: Enrolled in the study were 31 patients with NET eligible for TRT with [90Y-DOTA(0),Tyr(3)]octreotide (90Y-DOTATOC). Their mean age was 54 ± 14years. Of these 31 patients, 21 (67%) were referred for the first treatment cycle, while 10 (33%) were referred for a subsequent therapy cycle. Patients were treated with therapeutic doses of 90Y-DOTATOC ranging from 7,030 to 35,520MBq. To inhibit tubular reabsorption of 90Y-DOTATOC, 1l of physiological saline solution containing 25g of arginine hydrochloride and 25g of lysine hydrochloride was given over 4h starting 1h before 90Y-DOTATOC injection. All patients underwent a standard biochemical blood analysis at baseline, and 4h and 24h after the beginning of the amino acid infusion. Results: ANOVA repeated measures showed a significant overall effect on K+ levels over time (F = 118.2, df = 2, P 0.05) to baseline K+ levels. Intravenous administration of 40mg furosemide 1h after the beginning of the amino acid infusion did not have a significant effect on K+ levels (P>0.05). No clinical characteristic was predictive for the increase in K+ levels (chi-squared test, P > 0.05). Conclusion: Hyperkalaemia is a frequent, potentially life-threatening side effect of basic amino acid infusion during TRT. K+ levels 4h after the beginning of the infusion should be monitored in patients at risk of complications, such as those with heart disease and those with risk factors for nephrotoxicit