Plasma and red blood cell zinc in cystic fibrosis

Zinc status in cystic fibrosis patients; a systematic review and meta-analysis

Background

Cystic fibrosis (CF) is an autosomal recessive hereditary disease causes concentration of secretions and this affects the lungs and digestive system. These patients are exposed to zinc (zn) deficiency. In this review, we decided to investigate the status of zn in CF patients compared to control group. Also, the clinical trials that have so far performed zinc supplementation in these patients are examined.

Method

ISI Web of Science, Scopus, PubMed/Medline, and Cochrane database were searched, up to December 2023, for studies that reported the association between zn levels of CF patients compared to a healthy control group. A random-effect model was used to compute the pooled weighted mean difference (WMD) with 95 % confidence intervals (CI). Subgroup analysis was done for region, sample and method of measurement, zinc supplementation and age.

Result

Overall, meta-analysis of 9 studies (n = 383 participants) revealed that the zn levels were significantly lower in children and adolescents with CF compared with healthy subjects (WMD = -11.97 μg/dL, 95 % CI: -22.57 to -1.37; I2 = 92.83 %). Meta-analysis of 8 studies (n = 320 participants) revealed that the serum and plasma level of zn was significantly lower in CF patients compared with healthy subjects (WMD = -14.31 μg/dL, 95 % CI: -25.09 to -3.53; I2 = 88.14 %, P-heterogeneity <0.001) While the zn level in saliva and sputum was significantly higher in CF patients.

Conclusion

CF patients have decreased zn levels in circulatory reservoirs. zn may effective for the diminish the respiratory and gastrointestinal symptoms in CF patients, further well-designed clinical trial studies is required to prove these effects.

Evaluation of imprecision in the different detection methods of Zn based on 5 years of data from an external quality assessment program in China

BACKGROUND

This study examines the imprecision of zinc (Zn) measurements across various clinical detection methods by analyzing the external quality assessment (EQA) data from 2018 to 2022. The findings of this study aim to offer recommendations for enhancing Zn measurements.

METHODS

Participating laboratories were grouped into peer categories based on the detection methods. The robust mean and coefficient of variation (CV) of the samples were calculated following ISO 13528 guidelines. The evaluation criteria for optimal, desirable, and minimum allowable imprecision in Zn estimation are 2.50%, 5.05%, and 7.55%, respectively, based on biological variation. Furthermore, the study examined inter-lab CVs, inter-method bias, and the passing rate. The impact of sample concentration on CVs and the pass rate was also investigated.

RESULTS

Over the past five years, 4283 laboratories participated in the EQA program, showing a high pass rate that improved as sample concentration increased. Differential pulse polarography (DPP) demonstrated stable and low CVs (0.61-1.86%). Although differential pulse stripping (DPS) was less stable than DPP, it still exhibited a low CV (0.71-3.10%). Graphite furnace atomic absorption spectrometry (GFAAS) and flame atomic absorption spectrometry (FAAS) performed similarly and displayed stable CVs (2.39-4.42%) within the acceptable range of desirable imprecision (5.05%). However, the CVs for ICP-MS were unacceptable in three out of the five years (5.28-6.20%). In 2022, the number of participating laboratories for DDP, DPS, GFAAS, FAAS and ICP-MS is 131, 35, 35, 820 and 72, respectively.

CONCLUSION

This study provides reliable insights into the imprecision of Zn measurements in clinical laboratories. The findings indicate that additional efforts are required to reduce the imprecision of ICP-MS in Zn measurements.

The Role of Zinc in Developed Countries in Pediatric Patients: A 360-Degree View

Zinc is an important trace element for growth and health at pediatric ages. Zinc is fundamental in inflammatory pathways, oxidative balance, and immune function. Zinc exhibits anti-inflammatory properties by modulating Nuclear Factor-kappa (NF-κB) activity and reducing histamine release from basophils, leukocytes, and mast cells. Furthermore, its antioxidant activity protects against oxidative damage and chronic diseases. Finally, zinc improves the ability to trigger effective immune responses against pathogens by contributing to the maturation of lymphocytes, the production of cytokines, and the regulation of apoptosis. Given these properties, zinc can be considered an adjunctive therapy in treating and preventing respiratory, nephrological, and gastrointestinal diseases, both acute and chronic. This review aims to deepen the role and metabolism of zinc, focusing on the role of supplementation in developed countries in pediatric diseases.

CFTR is required for zinc-mediated antibacterial defense in human macrophages

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion transporter required for epithelial homeostasis in the lung and other organs, with CFTR mutations leading to the autosomal recessive genetic disease CF. Apart from excessive mucus accumulation and dysregulated inflammation in the airways, people with CF (pwCF) exhibit defective innate immune responses and are susceptible to bacterial respiratory pathogens such as Pseudomonas aeruginosa. Here, we investigated the role of CFTR in macrophage antimicrobial responses, including the zinc toxicity response that is used by these innate immune cells against intracellular bacteria. Using both pharmacological approaches, as well as cells derived from pwCF, we show that CFTR is required for uptake and clearance of pathogenic Escherichia coli by CSF-1-derived primary human macrophages. CFTR was also required for E. coli-induced zinc accumulation and zinc vesicle formation in these cells, and E. coli residing in macrophages exhibited reduced zinc stress in the absence of CFTR function. Accordingly, CFTR was essential for reducing the intramacrophage survival of a zinc-sensitive E. coli mutant compared to wild-type E. coli. Ectopic expression of the zinc transporter SLC30A1 or treatment with exogenous zinc was sufficient to restore antimicrobial responses against E. coli in human macrophages. Zinc supplementation also restored bacterial killing in GM-CSF-derived primary human macrophages responding to P. aeruginosa, used as an in vitro macrophage model relevant to CF. Thus, restoration of the zinc toxicity response could be pursued as a therapeutic strategy to restore innate immune function and effective host defense in pwCF.

Update on the management of vitamins and minerals in cystic fibrosis

Advancements in respiratory and nutrition management have significantly improved the survival of patients with cystic fibrosis (CF). With the availability of several nutrition interventions such as oral/enteral nutrition supplements, enteric‐coated pancreatic enzymes, and water‐miscible CF‐specific vitamin supplements, frank vitamin deficiencies—with the exception of vitamin D—are rarely encountered in current clinical practice. Whereas they were previously considered as micronutrients, our current understanding of fat‐soluble vitamins and minerals as antioxidants, immunomodulators, and disease biomarkers has been evolving. The impact of highly effective modulators on the micronutrient status of patients with CF remains elusive. This narrative review focuses on the updates on the management of fat‐soluble vitamins and other micronutrients in CF in the current era and identifies the gaps in our knowledge.

The Role of Zinc in the Pathogenesis of Lung Disease

Lung diseases, such as asthma, chronic obstructive pulmonary diseases (COPD), and cystic fibrosis (CF), are among the leading causes of mortality and morbidity globally. They contribute to substantial economic burdens on society and individuals. Currently, only a few treatments are available to slow the development and progression of these diseases. Thus, there is an urgent unmet need to develop effective therapies to improve quality of life and limit healthcare costs. An increasing body of clinical and experimental evidence suggests that altered zinc and its regulatory protein levels in the systemic circulation and in the lungs are associated with these disease’s development and progression. Zinc plays a crucial role in human enzyme activity, making it an essential trace element. As a cofactor in metalloenzymes and metalloproteins, zinc involves a wide range of biological processes, such as gene transcription, translation, phagocytosis, and immunoglobulin and cytokine production in both health and disease. Zinc has gained considerable interest in these lung diseases because of its anti-inflammatory, antioxidant, immune, and metabolic modulatory properties. Here we highlight the role and mechanisms of zinc in the pathogenesis of asthma, COPD, CF, acute respiratory distress syndrome, idiopathic pulmonary fibrosis, and pulmonary hypertension.

Zinc status and growth in infants and young children with cystic fibrosis

BACKGROUND

Zinc deficiency is associated with poor growth in children without cystic fibrosis (CF), but its impact on growth in children with CF is unknown.

OBJECTIVE

To determine the prevalence of low serum Zn (sZn) and its relationship with growth in the first 3 years of life in children with CF.

METHODS

We utilized data from infants with CF who were enrolled in a longitudinal study of nutrition and lung health and had sZn measured as part of clinical care. Cross-sectional correlations between sZn levels and growth z scores were assessed by Pearson's correlation coefficient. To identify factors associated with sZn status and its association to longitudinal growth patterns, multiple regression analysis with repeated measures were performed using generalized estimating equations.

RESULTS

A total of 106 sZn measurements from 53 infants were identified. Seventeen infants (32%) had intermittent Zn insufficiency, defined as at least one sZn <70 mcg/dl in their first 3 years of life. There were no significant cross-sectional associations between sZn and growth z scores. However, analysis of longitudinal growth patterns revealed that weight- and length-for-age z scores in children with intermittent Zn insufficiency were lower during early infancy and their weight-for-length z scores at age 3 years were also lower compared to those who were always Zn sufficient.

CONCLUSION

Low sZn occurs in one-third of children with CF in the first 3 years of life. Cross-sectional and longitudinal analyses revealed discrepant associations between sZn and growth. Therefore, prospective studies are needed to understand the role of Zn in growth in CF.

Laboratory Test Ordering Patterns in Pediatrics From Naturopaths and General Practitioners

OBJECTIVES

Naturopathic medicine emphasizes prevention and the self-healing process through natural therapies. Naturopathic doctors (NDs) use clinical laboratories as frequently as traditionally trained physicians. Here we evaluated the test-ordering patterns of NDs and general practitioners (GPs).

METHODS

A retrospective analysis was performed from a tertiary pediatric hospital. We analyzed tests ordered by NDs who used laboratory services and compared the test ordering patterns with GPs from adolescent medicine, family medicine, or pediatric clinics. Requests were categorized into 10 groups. We determined the tests with the highest ordering frequencies, as well as the percentage of tests that had an abnormal result.

RESULTS

NDs ordered more tests per patient per date of specimen collection compared with GPs. The most frequently ordered tests by NDs were trace elements and toxic metals (23.2% of total), allergens (21.8%), and general chemistry (15.3%). For the same test, the percentage of tests with an abnormal result was significantly lower for NDs than GPs.

CONCLUSIONS

We observed different ordering patterns between NDs and GPs. NDs ordered more esoteric tests and had lower rates of abnormal test results compared with GPs. Understanding the patterns of testing from different providers' specialties is useful to choose effective laboratory stewardship interventions.

Increased zinc and albumin but lowered copper in children with transfusion-dependent thalassemia

BACKGROUND

Measurements of copper and zinc in transfusion-dependent thalassemia (TDT) show contradictory results.

AIM OF THE STUDY

To examine serum levels of these minerals in TDT in relation to iron overload indices and erythron variables.

METHODS

This study recruited 60 children with TDT and 30 healthy controls aged 3-12 years old.

RESULTS

Zinc was significantly higher in TDT children than in controls, while copper and the copper to zinc ratio were significantly lowered in TDT. Serum zinc was significantly associated with the number of blood transfusions and iron overload variables (including serum iron and TS%) and negatively with erythron variables (including hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin). Serum copper was significantly and negatively associated with the same iron overload and erythron variables. The copper to zinc ratio was significantly correlated with iron, TS%, ferritin, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin. Albumin levels were significantly higher in TDT children than in control children.

CONCLUSION

Our results suggest that the increase in zinc in children with TDT may be explained by iron loading anemia and hemolysis and the consequent shedding of high amounts of intracellular zinc into the plasma. Increased albumin levels and treatment with Desferral may further contribute towards higher zinc levels in TDT. We suggest that the elevations in zinc in TDT are a compensatory mechanism protecting against infection, inflammation, and oxidative stress. Previous proposals for prophylactic use of zinc supplements in TDT may not be warranted.

ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with cystic fibrosis

BACKGROUND

Malnutrition is both a frequent feature and a comorbidity of cystic fibrosis (CF), with nutritional status strongly associated with pulmonary function and survival. Nutritional management is therefore standard of care in CF patients. ESPEN, ESPGHAN and ECFS recommended guidelines to cover nutritional management of patients with CF.

METHODS

The guidelines were developed by an international multidisciplinary working group in accordance with officially accepted standards. The GRADE system was used for determining grades of evidence and strength of recommendation. Statements were discussed, submitted to Delphi rounds, reviewed by ESPGHAN and ECFS and accepted in an online survey among ESPEN members.

RESULTS

The Working Group recommends that initiation of nutritional management should begin as early as possible after diagnosis, with subsequent regular follow up and patient/family education. Exclusive breast feeding is recommended but if not possible a regular formula is to be used. Energy intake should be adapted to achieve normal weight and height for age. When indicated, pancreatic enzyme and fat soluble vitamin treatment should be introduced early and monitored regularly. Pancreatic sufficient patients should have an annual assessment including fecal pancreatic elastase measurement. Sodium supplementation is recommended and a urinary sodium:creatinine ratio should be measured, corresponding to the fractional excretion of sodium. If iron deficiency is suspected, the underlying inflammation should be addressed. Glucose tolerance testing should be introduced at 10 years of age. Bone mineral density examination should be performed from age 8-10 years. Oral nutritional supplements followed by polymeric enteral tube feeding are recommended when growth or nutritional status is impaired. Zinc supplementation may be considered according to the clinical situation. Further studies are required before essential fatty acids, anti-osteoporotic agents, growth hormone, appetite stimulants and probiotics can be recommended.

CONCLUSION

Nutritional care and support should be an integral part of management of CF. Obtaining a normal growth pattern in children and maintaining an adequate nutritional status in adults are major goals of multidisciplinary cystic fibrosis centers.

Serum zinc concentration in cystic fibrosis patients with CFTR I1234V mutation associated with pancreatic sufficiency

OBJECTIVE

To determine serum zinc (Zn) level among cystic fibrosis (CF) patients with homozygous CFTR I1234V mutation associated with pancreatic sufficiency (PS).

METHODS

A cross-sectional study was conducted including both pediatric and adult CF patients. Data on age, weight, height, body mass index (BMI), BMI Z-score, FEV1, and chronic Pseudomonas aeruginosa infection were collected. Serum Zn, albumin, and total proteins were measured and analyzed.

RESULTS

Forty-five CF patients with homozygous CFTR I1234V mutation belonging to a large Arab kindred tribe and eight CF patients with other mutations associated with pancreatic insufficiency (PI). Patient's age ranged from 2 to 49 years with a mean age of 15.1 ± 9.1 years and mean plasma Zn of 0.78 ± 0.15 mcg/mL. Seven (13.2%) patients with CFTR I1234V and PS had low Zn levels (<0.6 mcg/mL). Mean age among Zn deficient group was significantly older. The mean FEV1 in the deficient group was found to be insignificant low. Persistent P. aeruginosa colonization was more prevalent in Zn deficient group. BMI Z-scosre of CF patients were positively correlated with Zn levels. Forty-five healthy subjects belonging to the same Arab tribe were selected in order to assess their Zn levels and their mean plasma Zn of 0.84 ± 0.11 mcg/mL (range 0.65-1.1 mcg/mL) with mean age 20.4 ± 10.1 years (range 6-40 years).

CONCLUSION

These findings suggest that Zn deficiency can occur in CF patients with PS. The association of Zn levels and the frequency of P. aeruginosa isolated in CF patients need further investigation.

Nutritional status in children with Shwachman-diamond syndrome

OBJECTIVE

In Shwachman-Diamond syndrome (SDS), pancreatic insufficiency can lead to malabsorption of fat-soluble vitamins and trace elements. The aim of this study was to assess the serum concentrations of vitamins A and E, zinc, copper, and selenium and their deficiencies.

METHODS

This retrospective review was performed in 21 children (12 were male; median age, 7.8 years) with genetically confirmed SDS at a tertiary pediatric hospital. Pancreatic enzyme replacement therapy (PERT) and vitamin or trace elements supplements were documented.

RESULTS

Twenty patients (95%) had pancreatic insufficiency receiving PERT, 10 (47%) had a combined vitamin and trace element deficiency, 6 (29%) had an isolated vitamin deficiency, and 4 (19%) had an isolated trace element deficiency. Vitamins A and E deficiency occurred in 16 (76%) and 4 (19%) of 21, respectively. Low serum selenium was found in 10 (47%), zinc deficiency in 7 (33%), and copper deficiency in 5 (24%). Eleven patients (52%) were on multivitamin supplementation, and 2 (10%) on zinc and selenium supplements. No statistical differences were found between repeated measurements for all micronutrients.

CONCLUSIONS

More than 50% of the children had vitamin A and selenium deficiencies despite adequate supplementation of PERT and supplements. Micronutrients should be routinely measured in SDS patients to prevent significant complications.

Evaluation of micronutrient profile of North Indian children with cystic fibrosis: a case-control study

BACKGROUND

Data on the micronutrient levels in children with cystic fibrosis (CF) are not available from developing countries, wherein the nutritional profile of children is quite different from that of Western countries.

METHODS

Levels of fat-soluble vitamins (A, D, and E) and trace metals (iron, copper, and zinc) were measured in 27 CF cases and 27 controls.

RESULTS

CF cases had significantly low levels of all studied micronutrients compared with controls, and the levels were even lower in cases with exacerbation than in stable CF cases. Prevalence of deficiency of vitamin D, vitamin E, iron, copper, and zinc was significantly higher in cases than in controls, whereas vitamin A deficiency was almost equal in both the groups.

CONCLUSION

The prevalence of deficiency of vitamins A, D, and E and iron, copper, and zinc was high in CF cases, and their levels were significantly lower in cases than controls. CF cases should be regularly monitored for these micronutrients, and appropriate supplementation should be considered.

Plasma zinc in adults with cystic fibrosis: correlations with clinical outcomes

BACKGROUND

Zinc status has been previously documented in cystic fibrosis (CF) infants, children and adolescents. However, despite the increasing life expectancy observed in CF populations, data regarding zinc status of CF adults are surprisingly lacking. The objectives of this study were to (1) characterize zinc status and (2) explore associations between zinc status and clinical outcomes of CF adult patients.

METHODS

A retrospective chart review was performed for patients who had their plasma zinc measured between 2009 and 2012. Data included demographics, clinical characteristics, biochemical parameters and co-morbid conditions.

RESULTS

A total of 304 CF patients were included in the study. These patients displayed a good nutritional status (mean BMI±SD: 22.7±3.5) and moderate lung disease (mean FEV1±SD: 66.3±22.2). Low plasma zinc concentration (<9.2μmol/L) was found in 68 out of 304 CF patients (22.4%). Compared to patients with normal zinc, those with low zinc had significantly lower forced vital capacity and forced expiratory volume in one second. 72% of CF adults with low zinc suffered from bone disease (vs 49% with normal zinc, p=0.037) and 79% had impaired glycemic status (vs 58%, p=0.016). Accordingly, negative correlations were found between plasma zinc and glucose (r=-0.139, p=0.0001), HbA1c (r=-0.237, p=0.0001) and fructosamine (r=-0.134, p=0.034). In multiple linear regression, albumin and glycemic status were significant predictors of plasma zinc.

CONCLUSION

Our data indicated that nearly one quarter of CF adults with good nutritional status and moderate lung disease had low plasma zinc concentration and that low zinc status was associated with worse clinical outcomes.

Nutrition management of pediatric patients who have cystic fibrosis

Since the identification of cystic fibrosis (CF) in the 1940s, nutrition care of patients who have CF has been a challenge. Through optimal caloric intake and careful management of malabsorption, patients are expected to meet genetic potential for growth. Yet factors beyond malabsorption, including nutrient activity at the cellular level, may influence growth and health. This article reviews nutrition topics frequently discussed in relationship to CF and presents intriguing new information describing nutrients currently being studied for their impact on overall health of patients who have CF.

Effect of zinc supplementation on respiratory tract infections in children with cystic fibrosis

Zinc (Zn) has significant anti-oxidant and anti-inflammatory activity. Zn deficiency can occur in subsets of patients with cystic fibrosis (CF) especially those with malabsorption and impaired growth. Although supplemental Zn has significantly reduced infections in various disorders, its efficacy has not been thoroughly investigated in CF. We performed a double blind placebo controlled pilot study to investigate the effect of daily 30 mg elemental Zn for 1 year on the rate of respiratory tract infections (RTIs), use of antibiotics and plasma cytokines in 26 children with CF (ages 7-18 years). Plasma Zn, Cu, inflammatory cytokines and ex vivo generation of IL-2 were measured at baseline and at the end of the study. The number of days of oral antibiotics was lower in Zn treated patients compared to placebo (P = 0.05). However, compared to placebo, the effect of Zn was greater in patients who exhibited low plasma Zn at baseline (P = 0.02) than those who had plasma Zn levels identical to normal subjects (P = 0.55). Zn supplementation was marginally effective in reducing percentage increase in plasma IL-6 and IL-8 while increasing the percentage change in ex vivo generation of IL-2 in isolated mononuclear cell. In conclusion, oral intake of 30 mg/day of Zn reduced the number of days of oral antibiotics used to treat RTIs in children with CF. A higher daily Zn dose may be needed to decrease RTIs and modify immune responses.

Serum zinc concentrations in cystic fibrosis patients aged above 4 years: a cross-sectional evaluation

AIM

Assess the risk of zinc (Zn) deficiency in the older cystic fibrosis (CF) population.

METHOD

Cross-sectional investigation of all CF patients above the age of 4 followed at the Ghent University center between 2002 and 2003. Data on age, weight, height z-score, pancreatic and pulmonary functions, chronic Pseudomonas infection, and CF transmembrane conductance regulator (CFTR) mutations were collected. Serum Zn, vitamins (vit) A and E, retinol-binding protein (RBP), albumin, sedimentation rate, total IgG, and cholesterol were determined. Serum Zn was compared with a local healthy control group (Van Biervliet et al., Biol Trace Elem Res 94:33-40, 2003) and with literature data (Hotz C, et al. Am J Clin Nutr 78:756-764, 2003).

RESULTS

101 patients (median age 16 years) were included. There was no difference in serum Zn concentration between CF patients and controls. In CF patients no difference in serum Zn concentration between pancreatic-sufficient or pancreatic-insufficient patients was seen. Serum Zn was not associated to nutritional status or height z-score. A significant association serum Zn to serum albumin (p < 0.0005) and to vit A (p < 0.01) was seen. No associations of serum Zn to serum vit E, RBP, cholesterol, or CFTR were present, but there is a significant association serum Zn to forced vital capacity (p < 0.01). Serum Zn was not associated to inflammatory parameters or chronic Pseudomonas infection.

CONCLUSION

Comparison of CF patients with local controls revealed no significant differences. However, because persisting steatorrhea increases Zn loss (Easley et al., J Pediatr Gastroenterol Nutr 26:136-139, 1998) and 12.6% of our population has a serum Zn below the p value of 2.5 of the NHANES II study (Hotz C, et al. Am J Clin Nutr 78:756-764, 2003), there could remain an increased risk of Zn deficiency in some CF patients. Furthermore, the association with pulmonary function needs more investigation.

[Validity and reliability of the St George's Respiratory Questionnaire in adults with cystic fibrosis]

OBJECTIVE

To study self-perceived quality of life in adults with cystic fibrosis (CF), and to assess the validity of the St George's Respiratory Questionnaire (SGRQ) for use in these patients.

PATIENTS AND METHODS

We studied 37 adults with CF who were in stable condition as indicated by their respiratory and nutritional status. Disease severity was assessed by spirometry in conjunction with a modified National Institutes of Health (NIH) scoring system and the Bhalla scale. Nutritional status was evaluated by measuring height and weight, calculating body mass index, analyzing bioelectric impedance, and performing various laboratory tests. The patients' quality of life was assessed using the SGRQ.

RESULTS

SGRQ scores were higher (indicating poorer quality of life) among patients with CF than in the general population or among patients with chronic obstructive pulmonary disease. Internal consistency coefficients indicated the SGRQ had good reliability (Cronbach alpha 0.864). Women with CF tended to score higher than men, although this difference was not statistically significantly. A statistically significant relationship was observed between SGRQ score and severity of pulmonary impairment (the more severe the impairment, the worse the patient's quality of life). Statistically significant positive relationships were found between SGRQ domains and age, body mass index, and body fat percentage. Significant negative relationships were found between these domains and the modified NIH score, the Bhalla score, forced expiratory volume in 1 second (expressed as a percentage of predicted), and somatomedin C and zinc levels.

CONCLUSIONS

Self-perceived quality of life is worse among adults with CF than in the general population or among patients with chronic obstructive pulmonary disease. The SGRQ is a valid instrument for analyzing health-related quality of life in adults with CF as it discriminates very well between different degrees of severity of pulmonary impairment and also have an appropriate intern consistency.

Plasma zinc and growth status in preadolescent children with cystic fibrosis

OBJECTIVE

To investigate plasma zinc status in relation to dietary and supplemental zinc intake, growth and pulmonary status in preadolescent children with cystic fibrosis (CF) and pancreatic insufficiency (PI).

METHODS

Fasting plasma zinc was assessed in children (age, 8-11 years) with CF and PI. Food (7-day weighed records) and supplemental zinc intake, serum alkaline phosphatase and albumin, pulmonary function (spirometry), coefficient of fat absorption (%COA, 72-hour fecal fat) and growth status [height adjusted for genetic potential (AHAZ), weight (WAZ) and BMI Z scores (BMIZ)] were assessed.

RESULTS

For the 62 children (32 males), mean plasma zinc (+/-SD) was 16.8 +/- 3.1 micromol/L (110 +/- 20 ug/dL). Sixty-five percent of the subjects had levels above the study reference range of 9.2 to 15.3 micromol/L (60-100 ug/dL); no subjects had low zinc levels. Median (range) total daily zinc intake was 279% (83-988%) recommended dietary allowance, growth status was suboptimal (mean +/- SD: AHAZ, -0.8 +/- 1.0; WAZ, -0.5 +/- 1.2; BMIZ, -0.2 +/- 1.1), and forced expiratory volume at 1 second (FEV1) was 92 +/- 13% predicted. Plasma zinc was not correlated with growth, pulmonary or alkaline phosphatase status. Plasma zinc was correlated with serum albumin (r = 0.25, P < 0.05) and was inversely correlated with coefficient of fat absorption (as %; r = -0.30, P = 0.02).

CONCLUSIONS

Under current patterns of care in CF Centers, total zinc intake and plasma zinc status were adequate. These findings suggest that zinc was not a limiting micronutrient for preadolescent children with CF and PI and mild-to-moderate lung disease, and not likely contributing to their suboptimal growth status.