Trace copper, zinc levels predict patients on hemodialysis who may be at nutritional risk
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Blood trace element levels, specifically copper, zinc and selenium, showed associations with nutritional risk for patients undergoing maintenance hemodialysis in China.
Conducting assessments of these levels could, according to Yun Liu, MD, PhD, of the department of nephrology at Guangzhou Red Cross Hospital at Jinan University, and colleagues, aid in more accurate risk predictions of malnutrition and protein-energy wasting in this patient population.
Blood trace elements
“Trace elements account for less than 0.01% of the human body weight,” Liu and colleagues wrote. “Patients undergoing maintenance hemodialysis (MHD) are potentially at risk for a deficiency of essential trace elements and an excess of toxic trace elements, both of which have a negative impact on health.”
To evaluate the relationship between blood trace element levels and nutritional status, researchers obtained blood samples from 118 patients who had been on dialysis for a median of 34 months (considered elements included manganese, lead, selenium, zinc and copper).
Malnutrition and protein-energy wasting were assessed utilizing the geriatric nutritional risk index, the nutritional risk screening 2002 and the seven-point subjective global assessment.
“Protein-energy wasting (PEW), as defined by the International Renal Nutrition and Metabolism Association, describes the state of protein and energy metabolism disorders in patients with acute and chronic renal dysfunction and is proven to be a strong risk factor for poor prognosis in MHD patients,” the researchers wrote. “Studies have shown that the incidence of PEW ranges from 18% to 75% in dialysis populations, depending on the assessment method. The seven-point subjective global assessment (SGA) and nutritional risk screening 2002 (NRS 2002) are widely used tools to define PEW for nutritional risk assessment. The geriatric nutritional risk index (GNRI) has been evaluated in adult patients undergoing MHD and was found to be suitable for the preliminary screening of PEW.”
Nutritional risk
Based on these screening tools, researchers determined 26.3% (NRS 2002), 28% (GNRI) and 49.2% (SGA) of the cohort were malnourished.
With nutritional risk defined by having a GNRI of 91.2 or below, study findings indicated higher blood copper levels and lower blood zinc or selenium levels were independently associated with nutritional risk (odds ratios of 1, 0.63 and 0.96, respectively). Further, when assessing nutritional status using the NRS 2002, patients who had a blood zinc level of less than 4.22 mg per L or a blood selenium level of less than 85 g per L showed an increased nutritional risk (ORs of 3.723 of 5.57).
“This study found that higher levels of blood copper, lower levels of blood zinc and lower levels of blood selenium are independently associated with a higher nutritional risk in patients undergoing MHD, establishing a theoretical basis for future studies,” Liu and colleagues concluded of the findings. “Prospective studies with larger sample sizes and oral supplementation should be conducted to define the ranges of blood or serum trace elements in patients undergoing MHD. The results of our study, combined with those of future studies, will allow for the appropriate oral supplementation of trace elements to provide patients undergoing MHD with a significant nutritional benefit.”
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