Zinc absorption in haemodialysis patients

Prevalence and determinants of low plasma zinc levels in adult peritoneal dialysis patients

OBJECTIVE

Zinc is an essential trace element, being a cofactor for almost 300 enzymes. As zinc is widely available in the diet, the European Best Practice Guidelines do not recommend routine supplementation in dialysis patients. However, some medicines prescribed to dialysis patients may potentially reduce absorption, and there may be increased losses with dialysis. As older and co-morbid patients are now treated by peritoneal dialysis (PD) we wished to determine the prevalence of patients with low plasma zinc levels.

DESIGN AND METHODS

We prospectively measured plasma zinc in 550 PD patients attending for their first peritoneal membrane assessment using atomic absorption spectroscopy. Body composition was determined by bioimpedance.

RESULTS

Plasma zinc was measured in 550 patients, mean age 58.7 years, 60.6% male, mean value 10.8 ± 2.2 umol/L, with 66.5% having low zinc levels (<11.5 umol/L). Normal plasma zinc was associated with haemoglobin (odds ratio (OR) 1.41 (95% confidence limits (95%CL) 1.22-1.63), serum albumin (OR 1.04 (95%CL 1.002-1.087), higher glucose dialysates L/day (OR 1.06 (1.001-1.129), and negatively with 24-hour urinary protein losses (OR 0.786 (95%CL 0.673-0.918) and age (OR 0.985 (95%CL 0.972-1.0). There was no association with dialysis adequacy, original renal disease or dietary protein estimation. Prescription of phosphate binders had no effect on zinc levels (10.7 ± 2.2 vs 10.8 ± 2.3 umol/L).

CONCLUSIONS

Most PD patients had low plasma zinc levels, associated with older age, probably reflecting reduced intake, urinary protein losses, and lower albumin and haemoglobin most likely linked to greater co-morbidity, low grade inflammation and volume expansion requiring higher glucose dialysates.

Association Between the Blood Copper-Zinc (Cu/Zn) Ratio and Anemia in Patients Undergoing Maintenance Hemodialysis

Copper (Cu) and zinc (Zn) imbalances are common in dialysis patients. This study aimed to investigate the relationship between the blood Cu/Zn ratio and anemia in patients undergoing maintenance hemodialysis (MHD) treatment. This cross-sectional study included patients undergoing MHD at our center in September 2019. Clinical and demographic data and blood samples were collected before the hemodialysis sessions, and the blood levels of Zn and Cu were measured by inductively coupled plasma mass spectrometry. Multivariable linear and binary logistic regression analyses were performed to study the relationship between blood Cu/Zn ratio and anemia. A total of 144 MHD patients were enrolled in this study. The patients had a mean age of 64.33 ± 13.39 years, a median dialysis vintage of 33.50 (16.25-57.50) months, with 66 being females (45.8%). The median blood Cu/Zn ratio was 15.55 (interquartile range: 12.47-20.31). Anemia was present in 99 patients (68.8%). Groups with higher hemoglobin levels had decreased blood Cu/Zn ratios (p < 0.05). After adjustments for confounding factors, higher blood Cu/Zn ratios were independently associated with lower hemoglobin levels and anemia in MHD patients based on multivariate linear and multivariate binary logistic regression, respectively, in different models. Our study found that the blood Cu/Zn ratio is independently associated with anemia in MHD patients, but prospective multicenter studies with larger sample sizes are still needed to determine the appropriate cutoff values for blood zinc, blood copper, and blood Cu/Zn levels in this patient population.

Lower Levels of Blood Zinc Associated with Intradialytic Hypertension in Maintenance Hemodialysis Patients

Intradialytic hypertension (iHTN) has been related with an increased risk of mortality, with imbalances in trace elements being frequent in maintenance hemodialysis (MHD) patients. The aim of this study was to analyze the relationships between the levels of blood trace elements and iHTN in MHD patients. A total of 144 MHD patients were enrolled in September, 2019 (66 females; 5616 hemodialysis treatments), with a mean age of 64.33 ± 13.39 years and median vintage of 33.50 (16.25-57.50) months. Patients exhibited an average peridialytic systolic blood pressure (SBP) change of - 4.18 ± 20.22 mm Hg in the next 3 months. Thirty-four (23.6%) patients had persistent iHTN (piHTN). These patients were characterized by older age, higher rate of hypozincemia, and modified Charlson comorbidity score, whereas lower blood zinc and hemoglobin, at the time of their recruitment. No significant difference in the levels of other blood trace elements was observed between groups. A general linear mixed (GLM) model showed that with every mg/L point lower mean blood zinc at baseline, the peridialytic SBP change was increased by 4.524 mm Hg (P < 0.001). Binary logistic model in modulate of the GLM model revealed that the lower level of blood zinc was associated with piHTN (OR = 0.433, 95 % CI 0.295 to 0.637, P < 0.001). Multivariate analysis confirmed both above results. Our study indicated that lower blood zinc was independently associated with piHTN in patients undergoing MHD, but prospective studies with larger population are still needed.

Serum Zinc Concentration Correlates With Ferritin Concentration in Patients Undergoing Peritoneal Dialysis: A Cross-Sectional Study

Background: Zinc deficiency is common and is associated with erythropoietin resistant anemia, dysgeusia, and hypogonadism in patients undergoing hemodialysis. However, the prevalence and clinical effects of zinc deficiency in patients undergoing peritoneal dialysis (PD) have not been determined. Methods: This was a retrospective, cross-sectional study. The prevalence of serum zinc deficiency and the clinical factors related to serum zinc concentration were determined in 49 patients undergoing PD [mean age 59.5 years (±14.8 years), 38/49 were men (78.6%), median PD period 24.0 months (12.5-45.0 months)]. A serum zinc concentration <60 μg/dL was defined as serum zinc deficiency, and a serum zinc concentration between 60 and 80 μg/dL as possible serum zinc deficiency. Results: Serum zinc deficiency was present in 51% (25/49) of the patients, and possible serum zinc deficiency was present in 45% (22/49) of patients undergoing PD. Multivariate analysis showed that serum zinc concentration significantly correlated with serum ferritin concentration (β = 0.357, P < 0.01). Conclusions: The prevalences of serum zinc deficiency and possible serum deficiency are high and serum zinc concentration correlates with serum ferritin concentration in patients undergoing PD.

Association between dietary zinc intake and abdominal aortic calcification in US adults

BACKGROUND

In animal studies, zinc supplementation inhibited phosphate-induced arterial calcification. We tested the hypothesis that higher intake of dietary zinc was associated with lower abdominal aortic calcification (AAC) among adults in the USA. We also explored the associations of AAC with supplemental zinc intake, total zinc intake and serum zinc level.

METHODS

We performed cross-sectional analyses of 2535 participants from the National Health and Nutrition Examination Survey 2013-14. Dietary and supplemental zinc intakes were obtained from two 24-h dietary recall interviews. Total zinc intake was the sum of dietary and supplemental zinc. AAC was measured using dual-energy X-ray absorptiometry in adults ≥40 years of age and quantified using the Kauppila score system. AAC scores were categorized into three groups: no AAC (AAC = 0, reference group), mild-moderate (AAC >0-≤6) and severe AAC (AAC >6).

RESULTS

Dietary zinc intake (mean ± SE) was 10.5 ± 0.1 mg/day; 28% had AAC (20% mild-moderate and 8% severe), 17% had diabetes mellitus and 51% had hypertension. Higher intake of dietary zinc was associated with lower odds of having severe AAC. Per 1 mg/day higher intake of dietary zinc, the odds of having severe AAC were 8% lower [adjusted odds ratio 0.92 (95% confidence interval 0.86-0.98), P = 0.01] compared with those without AAC, after adjusting for demographics, comorbidities and laboratory measurements. Supplemental zinc intake, total zinc intake and serum zinc level were not associated with AAC.

CONCLUSIONS

Higher intake of dietary zinc was independently associated with lower odds of having severe AAC among noninstitutionalized US adults.

Variation of trace element concentrations in patients undergoing hemodialysis in the north of Spain

BACKGROUND

Trace elements are essential substances for the proper physiological and biochemical functioning of the organism. Hemodialysis patients are potentially at risk of deficiency or excess of these elements. The application of inductively coupled plasma mass spectrometry (ICP-MS) allows the simultaneous quantification of very small amounts of multiple trace elements. The aim was to measure the serum concentration of copper (Cu), zinc (Zn), selenium (Se), and nickel (Ni), and the whole blood concentration of arsenic (As), lead (Pb), and manganese (Mn), in patients undergoing hemodialysis as well as in controls.

METHODS

The study was carried out in 57 hemodialysis patients compared with 57 controls with normal renal function. Serum and whole blood samples from the dialysis group were collected before and after hemodialysis sessions and Cu, Zn, Se, Ni, As, Pb and Mn levels were determined using ICP-MS.

RESULTS

Hemodialysis patients showed significantly lower blood levels of Cu, Zn and Se than controls (p < 0.001) and higher concentrations of Ni, As and Pb (p < 0.0001). The levels of Mn were similar in both groups. After performing hemodialysis, Cu, Zn, Se and Ni concentrations were significantly higher than the pre-hemodialysis levels (p < 0.0001). However, the concentration of As decreased (p < 0.0001) and Pb and Mn levels were not significantly altered after the dialysis session.

CONCLUSION

Hemodialysis patients are at increased risk of trace elements deficiency (especially for Zn and Se) or excess (Ni) in respect to healthy subjects. Monitoring of blood levels and supplementation of some trace elements may be indicated in patients undergoing hemodialysis.

Does the choice of phosphate binder affect trace element levels in chronic kidney disease patients treated by regular haemodialysis?

BACKGROUND

Ion exchange resins have been reported to bind copper and zinc. As the phosphate binder sevelamer hydrochloride is an ion exchange resin, we audited trace element levels in our haemodialysis cohort to determine whether sevelamer prescription affected trace element levels compared with other phosphate binders.

METHODS

Samples for zinc, copper and selenium were taken in special tubes and measured by atomic absorption spectroscopy or inductively coupled plasma-mass spectrometry from 211 patients attending an inner city university hospital main dialysis centre.

RESULTS

Of the patients, 12.9% were prescribed oral or intravenous trace element supplementation. Of the remainder, 5.5% of patients had low plasma copper, 37.4% low zinc and 45.6% low selenium. There was no difference in copper (16.7 ± 0.2 vs 16.8 ± 0.4 μmol/L, respectively) and zinc (12.0 ± 0.3 vs 11.6 ± 0.2 μmol/L) comparing patients prescribed sevelamer compared with other phosphate binders. Despite a high prevalence of statin prescription, total cholesterol (3.42 ± 0.12 vs 3.89 ± 0.08, P < 0.01), LDL-cholesterol (1.46 ± 0.1 vs 2.00 ± 0.07, P < 0.01) and total cholesterol/HDL-cholesterol ratio (2.82 ± 0.15 vs 3.5216.7 ± 0.2 vs 16.8 ± 0.4 μmol/L, P < 0.01) were lower in the sevelamer group compared with those prescribed other phosphate binders. On logistic regression analysis, serum zinc levels were associated with serum albumin (F 20.36, β 0.174, CL 0.086-0.265, P < 0.001) and dialysis vintage (F 8.1, β 0.008, CL 0.002-0.013, P = 0.005), copper levels with log CRP (F 31.4, β 3.04, CL 0-1.97, P < 0.001) and urine volume (F 5.1, β - 0.01, CL - 0.002-0, P = 0.024), and selenium levels with serum albumin (F 23.2, β 0.016, CL 0.02-0.1, P < 0.001) and race (F 31.4, β 3.62, P = 0.032), with selenium levels being greater in non-Caucasoids (0.9 ± 0.02 vs 0.76 ± 0.02 μmol/L, P < 0.01).

CONCLUSIONS

Trace element and micronutrient deficiencies were relatively common in this inner city population of outpatient haemodialysis patients. However, the prescription of different phosphate binders did not have an observable effect on serum copper and zinc levels, but those prescribed sevelamer did have lower lipid profiles compared with those prescribed other phosphate binders. Trace element concentrations were more associated with albumin, a marker of general nutritional status, with some differences according to ethnicity, most likely due to differences in dietary intake.

Trace element status in hemodialysis patients

Patients with chronic kidney disease undergoing hemodialysis (HD) are potentially at risk of deficiency and excess of trace elements. HD exposes patients to large volumes of water (>120 l/week) in the form of dialysate. Although levels of certain ions (such as potassium and calcium) are carefully regulated in dialysate, many others are measured infrequently, if ever. As a result, substances in lower concentrations in the dialysis may be leached from the body. Conversely, toxic trace elements present in water but not in blood may accumulate and cause toxicity. Given that essential trace elements play key roles in multiple biological systems including immunological defense against oxidation and infection, it has been hypothesized that the increased morbidity and mortality seen in HD patients may in part be due to the imbalance of trace elements that has not been recognized. A recent systematic review has shown that compared with healthy controls, HD patients have significantly lower blood levels of zinc, manganese, and selenium, while blood levels of lead are likely to accumulate. Other trace elements, such as mercury and arsenic, are biologically plausible causes of excess mortality in dialysis patients, but available evidence is inconclusive as to whether they consistently accumulate in this population. Whether altered trace element levels are potentially reversible causes of adverse clinical outcomes in dialysis patients remains to be determined. This review highlights key issues related to this hypothesis, with special emphasis on zinc, manganese, selenium, lead, mercury, and arsenic.

Trace elements in hemodialysis patients: a systematic review and meta-analysis

BACKGROUND

Hemodialysis patients are at risk for deficiency of essential trace elements and excess of toxic trace elements, both of which can affect health. We conducted a systematic review to summarize existing literature on trace element status in hemodialysis patients.

METHODS

All studies which reported relevant data for chronic hemodialysis patients and a healthy control population were eligible, regardless of language or publication status. We included studies which measured at least one of the following elements in whole blood, serum, or plasma: antimony, arsenic, boron, cadmium, chromium, cobalt, copper, fluorine, iodine, lead, manganese, mercury, molybdenum, nickel, selenium, tellurium, thallium, vanadium, and zinc. We calculated differences between hemodialysis patients and controls using the differences in mean trace element level, divided by the pooled standard deviation.

RESULTS

We identified 128 eligible studies. Available data suggested that levels of cadmium, chromium, copper, lead, and vanadium were higher and that levels of selenium, zinc and manganese were lower in hemodialysis patients, compared with controls. Pooled standard mean differences exceeded 0.8 standard deviation units (a large difference) higher than controls for cadmium, chromium, vanadium, and lower than controls for selenium, zinc, and manganese. No studies reported data on antimony, iodine, tellurium, and thallium concentrations.

CONCLUSION

Average blood levels of biologically important trace elements were substantially different in hemodialysis patients, compared with healthy controls. Since both deficiency and excess of trace elements are potentially harmful yet amenable to therapy, the hypothesis that trace element status influences the risk of adverse clinical outcomes is worthy of investigation.

Prevalence of zinc deficiency and immune response in short-term hemodialysis

Zinc is an essential trace element for many biological functions, including immune functions. The mechanism by which zinc may affect the immune system is certainly multifaceted, due to zinc's widespread action on different enzymes, peptides, transcriptional factors and cytokines involved in the various physiological steps of immune development and reactivity. In this study, prevalence of zinc deficiency and alteration in complement system, immunoglobulins and T cell subsets depending on zinc levels were analyzed in short-term hemodialysis patients and compared with healthy controls. Plasma zinc levels were measured by flame atomic absorption spectrometry. Serum levels of complement C3 and C4, immunoglobulins G (IgG), M (IgM), and A (IgA), and prealbumin were measured by nephelometry depending on antigen-antibody reactions. Percentages of CD4 and CD8+ were calculated using a flow cytometer. Statistically significant decreased zinc levels, especially in the age group > or = 40 years, and increased C4, IgA, IgM, IgG and CD4+ levels were observed in hemodialysis patients. The prevalence of hypozincemia in hemodialysis patients was found to be 40%. A higher CD4+/CD8 ratio was also obtained in patients. We conclude that patients on maintenance hemodialysis for a short time exhibit zinc deficiency and disturbed immune response.

Copper and zinc determination in plasma and corpuscular components of peripheral blood of patients with preterminal and terminal renal failure

Homeostasis of trace elements is an essential condition for the activation and regulation of metabolic processes. Its disturbance results in clinical symptoms. Since most trace elements are eliminated via the renal system, their balance is disturbed in patients with preterminal or terminal renal insufficiency. However, only a low percentage of trace elements can be detected in plasma, so that the intracellular determination of trace elements in corpuscular components in peripheral blood cells might be of interest. After blood was taken from the shunt vessel, the cells were isolated by density gradient centrifugation media. The concentrations of the trace elements copper and zinc in peripheral blood cells and plasma were determined by means of electrothermal atomic absorption spectrometry. Compared with healthy blood donors, in patients with preterminal and terminal renal insufficiency concentrations in plasma and peripheral blood cells were altered but in different directions. In renal insufficiency copper concentration in plasma (median: 13.9 mumol/l) and erythrocytes (median: 0.8 mumol/ 10(9) cells) was normal and in the lower reference range, respectively, whereas copper concentration in the platelets was elevated (median of 20 mumol/1 10(9) cells). As regards zinc, patients with preterminal and terminal renal insufficiency both suffered from low values in plasma (median: 8.6 mumol/l). In contrast, the concentration in erythrocytes and thrombocytes was elevated (medians: 17.9 mumol/10(9) cells and 14.0 mumol/10(9) cells, respectively)). In conclusion, the intracellular determination of the trace elements copper and zinc is of value for diagnosis and monitoring of the trace element deficiency status.

[Effect of zinc substitution on lymphocyte subsets and cellular immune function in hemodialysis patients]

Infection is a major cause of morbidity and mortality in patients undergoing hemodialysis for end stage renal disease. Low plasma zinc levels have been associated with immunodepression in these patients. In a randomized, placebo controlled double-blind cross over study, plasma zinc levels, delayed hypersensivity to 7 Antigens (Merieux-Multitest), absolute lymphocyte counts, T- and B-lymphocytes, suppressor-T and helper T-cells and natural killer cells were studied in 25 hemodialysis patients before, during and after intravenous zinc supplementation for 8 weeks. The hemodialysis patients had significantly lower predialysis plasma zinc concentrations compared to 76 healthy controls (74 +/- 12 vs. 126 +/- 28 mcg/dl, p less than 0.001). The plasma zinc concentrations increased to the normal range during the treatment period. Lymphocyte subtype analysis showed a significant decrease of suppressor-T cells and an increase of the helper-T/suppressor-T ratio (2.09 +/- 0.26 vs. 3.18 +/- 0.48, p less than 0.05) after zinc supplementation. Delayed hypersensivity to intradermal antigens increased significantly only after zinc treatment (2.0 +/- 0.7 vs. 5.8 +/- 1.7, p less than 0.05), not after placebo. The changes were reversible after finishing the zinc treatment. It is concluded, that plasma zinc levels are reduced in hemodialysis patients and that the substitution of zinc restores some of the depressed immune functions in these patients.