Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 33  |  Issue : 1  |  Page : 122--126

Assessment of vitamin D in hemodialysis patients


Ahmed R El-Arbagy1, Khaled M. A El-Zorkany1, Mohamed A Helwa2, Eslam A.M El-Khalifa3,  
1 Department of Internal Medicine, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Clinical Pathology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
3 Department of Internal Medicine, Shebin El-Kom Fever Hospital, Menoufia, Egypt

Correspondence Address:
Eslam A.M El-Khalifa
El-Batanon, Shebin El-Kom, Menoufia 32717
Egypt

Abstract

Objective To evaluate vitamin D status among our prevalent dialysis population to help rapid treatment and prevent complications. Background Hemodialysis patients have markedly higher rates of severe vitamin D deficiency and reduced ability to convert 25(OH) vitamin D into the active form 1, 25-dihydroxyvitamin D. Patients and methods This cross-sectional study includes 70 patients randomly selected from prevalent dialysis population in Elshohda Hospital in Menoufia, and 20 healthy participants with no chronic illness enrolled as a control group. Their 25(OH) vitamin D level was estimated, and individuals who had 25(OH) vitamin D level less than or equal to 30 ng/ml were considered 25(OH) vitamin D deficient and individuals who had 25(OH) vitamin D level more than 30 ng/ml were considered 25(OH) vitamin D sufficient. Patients were subjected to complete history taking and full clinical examinations, and peripheral blood samples were analyzed for complete blood picture, serum albumin, serum calcium, serum phosphorus, intact parathyroid hormone, and serum 25-hydroxyvitamin D. Results This study showed that 74.3% of patients had 25(OH) vitamin D level less than or equal to 30 ng/ml and 25.7% had 25 (OH) vitamin D level more than 30 ng/ml. The control group showed that 70% had 25(OH) vitamin D level less than 30 ng/ml and 30% had 25(OH) vitamin D more than 30 ng/ml. No significant association was found between 25-hydroxyvitamin D and age, sex, parathyroid hormone, BMI, duration of dialysis, calcium, and phosphorus. Conclusion Our study showed that most of our hemodialysis patients (74.3%) had vitamin D deficiency. This percentage is more than the deficiency in control group. No significant association was found between 25-hydroxyvitamin D and age, sex, intact parathyroid hormone (iPTH), calcium, phosphorus, BMI, and duration of dialysis.



How to cite this article:
El-Arbagy AR, El-Zorkany KM, Helwa MA, El-Khalifa EA. Assessment of vitamin D in hemodialysis patients.Menoufia Med J 2020;33:122-126


How to cite this URL:
El-Arbagy AR, El-Zorkany KM, Helwa MA, El-Khalifa EA. Assessment of vitamin D in hemodialysis patients. Menoufia Med J [serial online] 2020 [cited 2020 Sep 29 ];33:122-126
Available from: http://www.mmj.eg.net/text.asp?2020/33/1/122/281301


Full Text



 Introduction



One of the most important functions of the kidney is activation of vitamin D. It is synthesized in the epidermis of the skin after UVB exposure or ingested in diet and is transported to the liver by vitamin D-binding protein where it is hydroxylated in the 25 position to yield 25 hydroxyl vitamin D (calcidiol or calcifediol). Exposure to sunlight or dietary intake of vitamin D increases serum levels of 25-hydroxyvitamin D. 25-hydroxyvitamin D constitutes the major circulating form of vitamin D, and it is hydroxylated by the enzyme 1-alpha hydroxylase in the kidney to yield 1,25dihydroxy vitamin D, which is the active form of vitamin D, and this metabolite is responsible for the effect of vitamin D on calcium and phosphorus metabolism, bone health, and regulation of parathyroid function[1].

In chronic kidney disease (CKD), there are several mechanisms involved in decreased levels of 1-25-dihydroxyvitamin D, such as (a) decrease in renal mass will limit the quantities of 1-alphahydroxylase that are available for production of the active vitamin D metabolite and (b) counter-regulatory effects of increasing levels of fibroblast growth factor-23[2].

In addition to the classical pathway for activation of 25-(OH) vitamin D to 1, 25-(OH) 2 vitamin D, a peripheral autocrine pathway exists and results in calcitriol synthesis in a variety of peripheral extrarenal tissues[3].

Lower levels of serum vitamin D are associated with significant changes in mineral metabolism that adversely affect vascular function. Furthermore, lower levels of vitamin D are associated with upregulation of the renin–angiotensin system and subsequently lead to vasoconstriction and increased blood pressure, vascular stress, and ultimately, a higher degree of cardiovascular stress and workload. In relation to this, impaired hemodynamic control, baroreflex dysfunction, and poor autonomic nervous system control have been observed in the CKD population[4].

Vitamin D presents interesting pleiotropic effects for the patient with CKD (reduction of mortality, antiproteinuric effect, and anti-inflammatory properties). 'Native' vitamin D (cholecalciferol or ergocalciferol) administration in these patients also decreases parathyroid hormone (PTH) levels. Native vitamin D administration in patients with CKD is safe and does not lead to increased risk of vascular calcification, despite the known hypercalcemic and hyperphosphatemic properties of the molecule in its active form[5].

The aim of this work was to evalute the level of 25(OH) vitamin D in hemodialysis patients and its relation with calcium, phosphorus, and PTH.

 Patients and Methods



The work was started after obtaning approval from the Department of Nephrology in Elshohda Hospital and the research ethics committee in Menoufia Faculty of Medicine. A self-report questionnaire was given to participants after obtaining their written consent. The questionnaire was designed by the investigator. Each patient was asked to fill the questionnaire and examined. They were ensured that all gathered information would be kept confidential and the participants would be anonymous. Each questionnaire was handed in an envelope to the patients, and after filling it, the participant sealed the envelope and put it in a basket containing other sealed envelopes.

A total of 70 patients on maintenance hemodialysis (were selected from the dialysis unit of Elshohda Hospital in Menoufia government, during the period from January 2017 to July 2017. The patients' age ranged from 25 to 75 years. There were 41 males and 29 females. The duration of dialysis ranged from 5 month to 15 years. We exculded patients with active infection, with hepatic insufficiency, with uncontrolled thyroid disease, and under chemotherapy treatment.

Controls

A total of 20 age-matched and sex-matched healthy volunteers without any known chronic diseases were used as a control group.

Method

All patients underwent detailed history evaluation, including age, sex, duration of dialysis, dose of dialysis, and full clinical examinations to detect the original disease responsible for the renal failure. Nutritional assessment was done through evaluation of BMI and nutritional parameters such as serum albumin and complete blood picture. Peripheral blood samples were analyzed for complete blood picture. Serum albumin and serum phosphorus were estimated by colorimetry (end point) using available kit (MDSS GmbH, Schiffgraben, Germany), serum calcium was measured by colorimetry using available kit (GmbH, Holzheim, Germany), iPTH by enzyme-linked immunosorbent assay using available kit (Arigo, Gongyuan, Taiwan), and serum 25-hydroxyvitamin D was measured by enzyme-linked immunosorbent assay using available commercial kit (Pelobiotech GmbH, Planegg, Germany). We compared the patients' age, sex, duration of dialysis, BMI, and iPTH, with 25(OH) vitamin D levels.

Statistical analysis

Data were collected, tabulated, and statistically analyzed using a personal computer with statistical package of social science, version 20 and Epi Info 2000 programs (SPSS Inc., Chicago, Illinois, USA). Data were expressed into two phases: descriptive statistics, for example, number, percentage, mean, and SD. Arithmetic mean was used as a measure of central tendency. SD was used as a measure of dispersion. Percentage (%) was any proportion or share in relation to the whole. Analytic statistics were used to find out the possible association between studied factors and the targeted disease. The used tests of significance included the following:

Student t test: it is a test of significant used for comparison between two groups having quantitative variables and with independent parametric dataMann–Whitney test is a test of significant used for comparison between two groups having quantitative variables with independent nonparametric data.

Pearson's correlation

It is used to study the correlation between normally distributed quantitative variables. P value at 0.05 was used to determine significance: P value more than 0.05 to be statistically insignificant, P value less than or equal to 0.05 to be statistically significant, and P value less than or equal to 0.001 to be highly statistically significant.

 Results



Characteristics history of studied patients (N = 70) shows the highest percent of study population was male (58.6%), and the mean duration of dialysis was 4.5 ± 3.2 years [Table 1].{Table 1}

Comparison between cases and control regarding demographic data (N = 70) shows no significant correlation between case and control regarding sex and age, as their P value was not equal to or less than 0.05 [Table 2].{Table 2}

Hepatitis C virus infection and causes of hemodialysis among studied patients (NO = 70) show that the percent of hepatitis C virus in the study group was 47.1% (N = 33). Overall, 15 patients received treatment and 18 were not treated. Moreover, it shows that the highest percent of the disease among the study group was hypertension nephropathy (37.1%), and these hypertensive patients were on calcium channel blocker and beta blocker drugs, followed by 25.7% (N = 18) of study group who had diabetic nephropathy, where eight of them were on insulin therapy and 10 were on oral hypoglycemic drug, 10% of study group have disease of unknown origin, 8.6% have obstructive nephropathy, 5.7% of the study group have analgesic nephropathy and glomerulonephritis, 4.3% have polycystic kidney, and only 1.4% of study group have lupus nephritis and chronic pyelonephritis [Table 3].{Table 3}

Prevalence of 25(OH) vitamin D among studied patients (N = 70) shows that 74.3% of the study group had vitamin D level 30 or less and 25.7% of the study group had vitamin D more than 30 [Table 4].{Table 4}

Comparison between cases and control regarding vitamin D level shows that the value of vitamin D in studied patients was 22.3 and its value in control group was 28 [Table 5].{Table 5}

Correlation between 25(OH) vitamin D and other parameter shows no significant correlation between vitamin D value and BMI, duration of dialysis, calcium, phosphorus and PTH, as their P value was not equal to or less than 0.05, but there is a significant correlation with albumin, as P value is 0.009 [Table 6].{Table 6}

 Discussion



25(OH) vitamin D deficiency is prevalent in patients with end stage renal disease (ESRD) receiving hemodialysis. The reason for deficiency of 25(OH) vitamin D in these patients is multifactorial; inactivity of patients undergoing replacement therapy, limited exposure to sunlight, a minimal dietary intake of foods containing vitamin D, and the altered skin synthesis of vitamin D related to uremia have been proposed. Inadequate vitamin D level is associated with increased morbidity and mortality in this group of patients. In this study, we are aiming to evaluate the vitamin D status among our prevalent dialysis population. We have noticed that 52 (74.3%) of 70 patients had 25(OH) vitamin D level less than or equal to 30 ng/ml and 18 (25.7%) patients had 25(OH) vitamin D level more than 30 ng/ml.

Our findings were in agreement with Wolf et al.[6], who showed in a cross-sectional study that included 825 consecutive patients from 569 unique hemodialysis centers that only 22% of patients had 25D levels more than 30 ng/ml, whereas 78% were considered vitamin D deficient. Of those who are deficient, 60% had levels between 10 and 30 ng/ml, and the remaining 18% were severely vitamin D deficient (<10 ng/ml).

Moustapha Cisse et al.[7] focused on the prevalence of 25 (OH) vitamin D in black individuals living in a sunny region. This descriptive study took place at three hemodialysis centers in Dakar and included 37 patients whose 25-hydroxyvitamin D levels had been assayed. The patients' mean age was 51 years, and their sex ratio was 1.49. Below-normal 25(OH) vitamin D level was found in 23 (62.2%) patients, especially among those aged 50–75 years.

In our study, we found that there is no significant relationship between sex and the state of 25(OH) vitamin D. Our findings were in agreement with Mirchi et al.[8], who found in a cross-sectional study that no significant association was found between 25-hydroxyvitamin D levels and sex. In contrast to our study, Krause et al.[9] showed a significant relationship between sex and the state of 25(OH) vitamin D. Vitamin D deficiency was more in females than in males, with severe deficiency (level <12.5) being more pronounced in females (49.3%) than in males (35.5%).

In our study, we found that there is no significant correlation between iPTH and the level of 25(OH) vitamin D. Our findings were in agreement with Coen et al.[10], who showed similar findings in a retrospective study. The study was performed on a cohort of 104 patients on hemodialysis for more than 12 months. The patients were divided in three groups, according to the serum levels of 25(OH) vitamin D. The first group, with 25(OH) vitamin D levels between 0 and 15 ng/ml, whereas patients with 25(OH) vitamin levels between 15 and 30 ng/ml and above 30 ng/ml were in a second group and third group, respectively. There was no significant difference between the 25(OH) vitamin groups for what concerns serum iPTH. Wolf et al.[6] found that 25D levels correlated weakly with serum levels of PTH (r = −0.14). Patients with vitamin D deficiency had slightly increased PTH levels compared with patients with normal 25D stores. Nevertheless, 79% of patients with serum PTH less than 150 pg/ml were vitamin D deficient, with 25D levels less than 30 ng/ml.

In our study, we found that there is no significant correlation between duration of dialysis and the level of 25(OH) vitamin D. Our findings were in agreement with Clayton and Singer et al.[11], who measured 25-hydroxyvitamin D levels in 120 hemodialysis and 31 peritoneal dialysis patients and found that there was no correlation between vitamin D levels and duration of dialysis. Moreover, Mirchi et al.[8] showed that there is no significant correlation between duration of dialysis and the level of 25(OH) vitamin D.

In our study, we found there is no significant correlation between the level of 25(OH) vitamin D and serum calcium and phosphorus. Our findings were in agreement with Mirchi et al.[8].

In our study, we found that there is no significant correlation between BMI and the level of 25(OH) vitamin D. Our findings were in agreement with Mirchi et al.[8]. In contrast to our study, Del Valle et al.[12] found that there is a negative correlation with BMI.

 Conclusion



Our study showed that most of our patients undergoing hemodialysis have vitamin D deficiency, representing ∼74.3%. No significant association was found between 25-hydroxyvitamin D and age, sex, iPTH, calcium, phosphorus, BMI, and duration of dialysis. Therefore, vitamin D status of patient with CKD should be considered during their regular follow-up, and treatment for vitamin D should be initiated to reduce the risk of deficiency.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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