|Year : 2015 | Volume
| Issue : 2 | Page : 377-381
Study of serum zinc in vitiligo
Mohammed A Basha1, Rania M Azmy2, Ola A Amin1, Seham R Abd El-Khalik M.B.B.Ch 1
1 Department of Dermatogy, Andrology and S.T.Is, Menoufiya University, Menoufiya, Egypt
2 Department of Medical Biochemistry, Faculty of Medicine, Menoufiya University, Menoufiya, Egypt
|Date of Submission||15-May-2014|
|Date of Acceptance||22-Aug-2014|
|Date of Web Publication||31-Aug-2015|
Seham R Abd El-Khalik
Department of Dermatogy, Andrology and S.T.Is, Ashmoon Hospital, Ashmoon, Menoufiya 32811
Source of Support: None, Conflict of Interest: None
The aim of the study was to measure serum zinc level as a free radical scavenger in vitiligo patients to help us understand the pathogenesis of this disease entity.
Vitiligo is a common and chronic skin disease. A deficiency of antioxidant substances is found in vitiliginous skin. Zinc is considered an antioxidant that also plays an important role in the process of melanogenesis. In addition, studies have shown a variation in zinc level in patients with vitiligo.
Patients and methods
This study was conducted on 60 patients with vitiligo who were selected from the Dermatology Outpatient Clinic, Faculty of Medicine, Menoufia University Hospital, during the period from April 2013 to October 2013, and on 60 healthy controls. Serum zinc level was measured in both groups using a Flame Atomic Absorption Spectrophotometer.
Results showed that the mean zinc level of vitiligo patients was 104.0 ± 20.1 mg/100 ml and that of controls was 93.2 ± 19.5 mg/100 ml. The mean zinc level in both groups was found to be within the normal reference range and in vitiligo patients the mean zinc level was observed to be statistically significantly higher than that of controls (P < 0.05). There was a statistically significant association between serum zinc level in the studied cases and course of the disease as patients with progressive vitiligo showed significantly lower values.
In our study, serum zinc levels in patients with vitiligo were found to be within the normal range but higher than that of controls. Further studies may reveal a more significant relation between serum zinc and vitiligo.
Keywords: serum zinc, vitiligo, antioxidants
|How to cite this article:|
Basha MA, Azmy RM, Amin OA, Abd El-Khalik SR. Study of serum zinc in vitiligo. Menoufia Med J 2015;28:377-81
| Introduction|| |
Vitiligo is an acquired, noncontagious disease in which progressive, patchy, multifocal loss of pigmentation of skin, overlying hair, and often mucous membranes result from loss of melanocytes from the involved area  . Vitiligo lesions present as one or more amelanotic macules or patches that appear chalk-white or milk-white in color, surrounded by a normal or hyperpigmented border. Sometimes, the lesions have a red inflammatory border  . It occurs worldwide without racial, regional, or sex-related differences  . Approximately 50% of vitiligo cases have their onset before the age of 20 years and 25% before the age of 14 years  . Various physiological, biochemical, histochemical, and enzymatic studies have been carried out to determine the cause of the disease  . A plethora of evidence shows that the entire epidermis of patients with vitiligo has multiple signs of oxidative stress, including the presence of allantoin, massive amounts of hydrogen peroxide (H 2 O 2 ), and low catalase  . Research at the molecular level has demonstrated deficiency of antioxidant substances in vitiliginous skin. This leads to cytotoxic action of reactive oxygen species such as superoxide anion and hydroxyl radical, which are generated by the ultraviolet-damaged epidermis. The free radicals are also cytotoxic to melanocytes and inhibit tyrosinase  . Zinc is considered an antioxidant because of the dependency of the extracellular enzyme superoxide dismutase on zinc  . Zinc plays a vital role in the protection against free radical damage and takes part in the process of melanogenesis. Zinc catalyzes the rearrangement of dopachrome to form 5, 6-dihydroxy indole-2Ͳ-carboxylic acid (DICA) in the process of melanogenesis  .
| Patients and methods|| |
This study was conducted on 60 patients suffering from different types of vitiligo (focal, segmental, acrofacial, and generalized) and 60 healthy volunteers as the control group. Cases were selected from the Dermatology outpatient clinic, Faculty of Medicine, Menoufia University Hospital, during the period from April 2013 to October 2013. Written consent was obtained from every individual. Approval was obtained from the Ethical Committee of Human Rights in Research of Menoufia University before study initiation. The selected patients had newly developed lesions with no previous treatment for vitiligo and no intake of drugs containing zinc.
Presence of leukoderma secondary to other causes.
History of other obvious skin diseases.
Undergoing treatment with zinc or any history of zinc intake for 6 weeks before this study.
Suffering from any other systemic diseases such as cirrhosis of the liver, viral hepatitis, neoplastic condition, myocardial infarction, steatorrhea, or renal failure.
Pregnancy or consumption of oral contraceptive pills.
The diagnosis of vitiligo was made clinically using a Wood's lamp  .
Collection and preparation of serum samples
A volume of 5 ml of venous blood was collected from cases and control groups in special sterile tubes and centrifuged for 15 min at 2000 rpm. The supernatant serum was transferred to a separate sterile tube (Eppendorf tube) and kept at -20°C in the deep freezer until analysis. The serum zinc level was measured by 'Atomic Absorption Spectrophotometry (Flame method)  .
Student's t-test for continuous quantitative parametric variables and the Mann-Whitney U-test for nonparametric variables were conducted. Pearson's correlation coefficient for testing the association between variables was also applied. A P-value less than 0.05 was considered statistically significant. Analyses were conducted with an IBM personal computer and statistical package SPSS version 15 (Chicago, USA).
| Results|| |
The age of the selected patients ranged between 11 and 60 years, with a mean of 28.8 ± 20.0 and a median of 17.9. There were 26 male (43.3%) and 34 female (56.7%) patients, with a male to female ratio of 13 : 17. Forty patients presented with nonsegmental vitiligo (66.7%) and 20 with segmental vitiligo (33.3%). Thirty-two patients presented with lesions on the extremities (53.3%), eight had lesions on the head and neck (13.3%), and 20 presented with lesions on the trunk (33.3%). Four patients had a positive family history of vitiligo (6.7%) and six presented with leukotrichia (10%).
The duration of disease ranged between 2 and 124 months, with a mean of 34.6 ± 36.4 and a median of 20.0. Thirty-six patients had a stationary course (60.0%), 22 had a progressive course (36.7%), and two patients had a regressive course (3.3%).
The study result showed that the serum zinc level of patients ranged between 37 and 119 mg/100 ml, with a mean of 104.0 ± 20.1 and a median of 112.0. The mean ± SD of serum zinc level of controls was 93.2 ± 19.5 mg/100 ml. There was a statistically higher mean serum zinc level in cases compared with controls (P = 0.003). No correlation was found between serum zinc level and age or duration of disease in the studied cases (P = 0.04, 0.65). The mean value of the serum zinc level in the studied male patients was 103.1 ± 20.8 (mg/100 ml), whereas that in female patients was 104.7 ± 19.9 (mg/100 ml). Statistical analysis showed no significant difference (P = 0.76). There was no significant association between serum zinc level in the studied cases and site of the lesion of the disease (P = 0.59). There was no significant association between serum zinc level in the studied cases and clinical types of vitiligo (P = 0.37). There was no significant association between serum zinc level in the studied cases and positive family history (P = 0.54).
There was a statistically significant association between serum zinc level in the studied cases and course of the disease, as cases with progressive vitiligo showed significantly lower values (P<0.001). There was no significant association between serum zinc level in the studied cases and leukotrichia (P = 0.22). There was a statistically significant association between leukotrichia and duration of the disease in the studied cases where cases with leukotrichia showed significantly lower zinc level (P = 0.04) [Table 1] [Table 2] [Table 3] [Table 4] [Table 5].
|Table 2 Comparison between cases and controls with respect to serum zinc level|
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|Table 3 Comparison between course of disease and serum zinc level in the studied cases|
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|Table 5 Comparison between leukotrakia and serum zinc level in the studied cases|
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| Discussion|| |
Vitiligo is an acquired pigmentary disorder characterized by the presence of well-circumscribed depigmented milky white macules and patches  resulting from the loss of melanocytes from the epidermis, mucous membrane, inner ears, eyes, hair, and occasionally from the hair bulbs  . The pathogenesis of vitiligo is poorly understood. The main reason lies in the multifactorial nature of the disease, which progresses as a result of the interplay between multiple genes and environmental factors  . One of the recent hypotheses for explaining the triggering event of melanocyte destruction in vitiligo is the oxidative stress induced by reactive oxygen species  . Although a system of enzymatic and nonenzymatic antioxidants scavenge these free radicals and provide protection, an imbalance between oxidants and antioxidants leads to accumulation of free radicals, which damages cellular components such as protein, carbohydrate, DNA, and lipids  . Zinc is a trace element in biological systems. Numerous aspects of cellular metabolism are zinc-dependent. Zinc plays important roles in growth and development, the immune response, neurological function, and reproduction. At the cellular level, the function of zinc can be divided into three categories: catalytic, structural, and regulatory  . Zinc deficiency impairs growth and development, decreases the resistance to local infection, delays wound healing, and may produce hyperkeratotic skin lesions, apathy, depression, behavioral changes, and taste disturbances  .
In the present study, serum zinc level in both cases and controls was within the normal range but significantly higher serum zinc was found in cases than in controls. This finding was not in agreement with that of Shameer et al.  , who showed some interesting correlations between low zinc levels and vitiligo, nor with the results of Inamadar and Palit  , who reported the appearance of vitiligo-like depigmented cutaneous lesions in two siblings with acrodermatitis enteropathica who developed decreased serum zinc level due to discontinuation of zinc supplements. However, this study was in agreement with that of Helmy et al.  , who showed that serum zinc and copper levels were significantly higher in active vitiligo patients compared with controls because of the higher percentage of apoptotic peripheral blood mononuclear cells in active vitiligo with increased release of zinc and copper in serum. Our results did not agree with those of Arora et al.  , who found no significant alteration in serum zinc level in vitiligo.
In the present study the age of the selected patients ranged between 11 and 60 years with a mean of 28.8 ± 20.0 and a median of 17.9. No correlation was found between serum zinc level and age in the studied cases. In addition, the current study showed female predominance (56.7%). The mean value of the serum zinc level in the studied men was 103.1 ± 20.8 (mg/100 ml), whereas that in women was 104.7 ± 19.9 (mg/100 ml); no correlation was found between serum zinc level and sex. According to Shameer et al.  , the mean age at presentation was 33.8 years and the mean age at onset was 29.2 years. The male to female ratio was 4.5 : 1, showing a male predominance. Analysis of the zinc level revealed a reduced level in 13 (21.6%) of the 60 patients. Eleven (22%) of 49 male patients and two (18%) of 11 female patients showed reduced zinc levels. In the present study, the duration of disease ranged between 2 and 124 months, with a mean of 34.6 ± 36.4 and a median of 20.0. No correlation was found between serum zinc level and duration of disease in the studied cases. In the study by Shameer et al.  , the mean duration of disease was 2 years. The levels of serum zinc were low in the majority of patients with a duration of disease ranging from 2 to 5 years.
In the present study 40 patients presented with nonsegmental vitiligo (66.7%) and 20 with segmental vitiligo (33.3%). There was no significant association between serum zinc level in the studied cases and clinical types of vitiligo. According to Shameer et al.  , 11 of 51 patients with vitiligo vulgaris and two of six patients with mucosal vitiligo showed reduced levels of zinc. In the present study four patients had a positive family history of vitiligo (6.7%). No significant association was found between serum zinc level in the studied cases and positive family history. In the study by Shameer et al.  33% of patients had a positive family history of vitiligo.
In the present study 32 patients presented with lesions on the extremities (53.3%), 8 had lesions on the head and neck (13.3%), and 20 presented with lesions on the trunk (33.3%). No significant association was found between serum zinc level in the studied cases and site of the lesion. In the study by Shameer et al.  , the most common site of involvement was the lower extremity. Of the 40 patients with mucosal involvement, eight (20%) had reduced zinc levels.
In the present study, there was a statistically significant association between serum zinc level in the studied cases and course of the disease as patients with progressive vitiligo showed significantly lower values(P<0.001). In the study by Shameer et al.  , of the 13 patients with reduced zinc levels, six had unstable vitiligo.
In the present study, six cases presented with leukotrichia (10%). No significant association was found between serum zinc level in the studied cases and leukotrichia. In the study by Shameer et al.  , only one of six patients with leukotrichia had reduced zinc levels.
| Conclusion|| |
In some earlier studies a variable degree of correlation was observed between serum zinc level and vitiligo. A recent study conducted in India showed low level of serum zinc to be a significant risk factor for vitiligo. This study, in contrast, has shown significantly higher levels of serum zinc in vitiligo patients compared with controls. Thus, we recommend a study of longer duration with a larger sample size. In addition, a multicenter study should be carried out to reveal the accurate pattern of zinc status in vitiligo.
| Acknowledgements|| |
Conflicts of interest
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]