Selenium and zinc plasmatic levels in intensive care patients

The study was aimed at investigating plasmatic levels of zinc (Zn) and selenium (Se) in critical care patients, and the influence of standard supplementation of those elements on such levels.

Materials and methods

One hundred and eighty-one measurements were made in 55 patients. They were divided into two groups: CARDIO group, 18 patients after cardiovascular surgery, well nourished, without supplementation of trace elements; ICU group, 37 patients in acute protein catabolism with daily average suplementation of 0.89 mmol (70 mg) Se and of 107 mmol (7 mg) Zn. On days 0, 2, 3 and 7 of the hospitalization the following factors were monitored: (1) plasmatic levels of Se and Zn using atomic absorption spectrophotometry and electrothermic atomisation, and (2) prealbumin, albumin and CRP turbidimetrically, orosomucoid nephelometrically. By means of the last four parameters the prognostic nutritonal index (PINI) was calculated.

Reference values

Se 0.58–1.82 mmol/l, Zn 10.9–18.4 mmol/l, PINI ≤ 1.0, CRP 0–10 mg/l.

Statistical methods

Multiple regression analysis, one-way ANOVA, Bonferroni multiple comparison test, Kruskal–Wallis multiple comparison Z value test.

Results

Mean values and standard deviations for both groups of patients on days 0, 2, 3, and 7 were as follows. CARDIO group: Zn (mmol/l): 13.1 ± 2.8, 5.5 ± 2.0, 8.1 ± 1.8, 9.4 ± 2.5, Se (mmol/l): 0.39 ± 0.22, 0.24 ± 0.15, 0.24 ± 0.14, 0.29 ± 0.16. ICU group: Zn mmol/l: 8.2 ± 2.6, 8.6 ± 2.3, 8.7 ± 2.7, 8.7 ± 3.3, Se (mmol/l): 0.26 ± 0.20, 0.28 ± 0.15, 0.30 ± 0.14, 0.42 ± 0.24. The markers of inflamation were as follows: CARDIO group: PINI: 9.0 ± 32, 28 ± 36, 103 ± 69, 36 ± 25, CRP (mg/l): 18 ± 38, 78 ± 41, 160 ± 89, 70 ± 41. ICU group: PINI: 236 ± 284, 181 ± 188, 115 ± 218, 110 ± 181, CRP (mg/l): 193 ± 145, 177 ± 127, 116 ± 193, 101 ± 112.

Zinc In the CARDIO group significant elevation of CRP and PINI prove the acute metabolic response to trauma, and their changes corespond to dynamics of Se and Zn levels. The decrease of Zn between the first and second investigation was significant (P < 0.001). The inverse dependence between Zn:CRP was also significant (P < 0.001, r = -0.387). For the ICU group the decrease of Zn levels is characteristic, lasting under Zn substitution. Neither the Zn:CRP relation, nor Zn:PINI were significant.

Selenium Levels in both groups were significantly decreased. In the CARDIO group the inverse dependency between Se:CRP (P < 0.01, r = 0.306) was again significant. In the ICU group there was significant dependence for the Se:CRP relation (P < 0.001, r = -0.293) and Se:PINI (P < 0.001, r = -0.308).

Conclusions

With respect to low Se and Zn levels in critical patients, their monitoring and higher than usually recommended substitution in indicated cases seems raesonable and directs our future work.