Micronutrients in critically ill patients with severe acute kidney injury – a prospective study

Abstract

Malnutrition is common in patients with acute kidney injury (AKi) and the risk of mortality is high, especially if renal replacement therapy is needed. Between April 2013 through April 2014, we recruited critically ill adult patients (≥18 years) with severe AKI in two University hospitals in London, UK, and measured serial plasma concentrations of vitamin B 1 , B 6 , B 12 , c and D, folate, selenium, zinc, copper, iron, carnitine and 22 amino acids for six consecutive days. In patients receiving continuous renal replacement therapy (CRRT), the concentrations of the same nutrients in the effluent were also determined. cRRt patients (n = 31) had lower plasma concentrations of citrulline, glutamic acid and carnitine at 24 hrs after enrolment and significantly lower plasma glutamic acid concentrations (74.4 versus 98.2 μmol/L) at day 6 compared to non-CRRT patients (n = 24). All amino acids, trace elements, vitamin C and folate were detectable in effluent fluid. In >30% of CRRT and non-CRRT patients, the plasma nutrient concentrations of zinc, iron, selenium, vitamin D 3 , vitamin c, trytophan, taurine, histidine and hydroxyproline were below the reference range throughout the 6-day period. In conclusion, altered micronutrient status is common in patients with severe AKi regardless of treatment with cRRt.

Acute Kidney Injury Incidence in Hospitalized Patients and Implications for Nutrition Support

“…In a study of critically ill patients with AKI, >30% of patients had tryptophan, taurine, histidine, and hydroxyproline levels below normal at 6 days post‐CRRT, supporting the concept that patients with AKI have altered amino acid balance. In the same study, patients undergoing CRRT had lower plasma levels of glutamic acid, carnitine, and citrulline at day 1 after starting CRRT and lower levels of glutamic acid at 6 days after starting CRRT 98 …”

“…99,100 Multiple studies have documented the loss of micronutrients, such as copper, zinc, selenium, folic acid, magnesium, vitamin C, vitamin E, thiamin, chromium, and iron. [98][99][100][101][102] In one study of patients undergoing CVVHD, different dialysis doses did not result in clinically relevant losses of folic acid, vitamin B 12 , zinc, magnesium, and inorganic phosphate. 100 This study specifically involved CVVHD and not other types of CRRT, so this may not be generalizable across all CRRT modalities.…”

“…In the same study, patients undergoing CRRT had lower plasma levels of glutamic acid, carnitine, and citrulline at day 1 after starting CRRT and lower levels of glutamic acid at 6 days after starting CRRT. 98…”

Clearance of micronutrients during continuous renal replacement therapy

“…We recently measured serial plasma concentrations of vitamins, trace elements, carnitine and 22 amino acids (AAs) for up to six consecutive days in 55 critically ill adult patients with severe AKI [5]. The main findings were that patients treated with continuous renal replacement therapy (CRRT) had significantly lower plasma concentrations of citrulline, glutamic acid and carnitine at 24 h after enrolment and significantly lower plasma glutamic acid concentrations at day 6 compared to non-CRRT patients.…”

“…Here, we report the SCs and daily total losses of AAs, vitamins, trace elements and carnitine of all 33 CRRT patients recruited to the study mentioned above [5]. Total daily loss was calculated as C pl × SC × effluent volume per day.…”