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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2014  |  Volume : 25  |  Issue : 5  |  Page : 998-1003
The evaluation of relationship between vitamin D and muscle power by micro manual muscle tester in end-stage renal disease patients

1 Department of Nephrology, Loghmanhakim Hospital, Shahid Beheshti University, Tehran, Iran
2 Department of Internal Medicine, Loghmanhakim Hospital, Shahid Beheshti University, Tehran, Iran
3 Department of Nephrology, Dr. Taleghani Hospital, Shahid Beheshti University, Tehran, Iran

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Date of Web Publication2-Sep-2014


Muscle force of lower limb is a major factor for sustaining physical activity. Decreased muscle force can limit physical activity, which can increase mortality and morbidity in end-stage renal disease (ESRD) patients. Muscle force depends on several factors. One of the most important factors is 25-hydroxy vitamin D (25-OHD) that affects muscle function in both uremic and non-uremic patients. The aim of this study was to investigate the association between serum level of 25-OHD and muscle force of lower extremities in hemodialysis patients estimated by a Micro Manual Muscle Tester, a digital instrument that measures muscle force in kilograms This cross-sectional study was performed on 135 adult patients, 69 male (51%) and 66 female (69%) (mean: 1.4, standard deviation: 0.5), undergoing hemodialysis. Standard biochemistry parameters were measured before hemodialysis, including 25-OHD, calcium, albumin, para­hyroid hormone and C-reactive protein (CRP). Based on the result of serum level of 25-OHD, patients were classified into the following three groups: 85 patients (63%) were 25-OHD deficient (25-OHD <30), 43 patients (32%) had a normal level of 25-OHD (30-70) and seven patients (5%) had a toxic level of 25-OHD (>70) (mean: 1.42, standard deviation: 0.59). Also, based on the result of muscle force, patients were classified into the following three groups: 84/133 patients (62%) had weak muscle force (<5 kg), 46/133 patients (34%) had normal muscle force (5-10 kg) and three patients (21%) had strong muscle force (>10 kg) (mean: 1.39, standard deviation: 0.53). There was a significant relation between 25-OHD level and muscle force (P = 0.02), between age and muscle force (P = 0.002) and between gender and muscle force (P <0.001). In our opinion, 25-OHD can be a useful drug in ESRD patients to improve muscle force and physical activity.

How to cite this article:
Zahed N, Chehrazi S, Falaknasi K. The evaluation of relationship between vitamin D and muscle power by micro manual muscle tester in end-stage renal disease patients. Saudi J Kidney Dis Transpl 2014;25:998-1003

How to cite this URL:
Zahed N, Chehrazi S, Falaknasi K. The evaluation of relationship between vitamin D and muscle power by micro manual muscle tester in end-stage renal disease patients. Saudi J Kidney Dis Transpl [serial online] 2014 [cited 2021 Dec 3];25:998-1003. Available from: https://www.sjkdt.org/text.asp?2014/25/5/998/139885

   Introduction Top

Muscle wasting and weakness are common in patients with end-stage renal disease (ESRD), and are major causes of limitation of physical activity, [1] which may lead to disability and diminished quality of life, [2] and are associated with increased morbidity and mortality in the ESRD population. Major causes of muscle wasting in ESRD are malnutrition, uremia, inadequate hemodialysis, chronic inflamma­tion, underlying disease (diabetes) and vitamin D deficiency. [4]

Vitamin D plays an essential role in muscle growth and development [5] as well as regulating muscle contractility. Numerous studies in humans and animals have demonstrated the effect of Vitamin D deficiency on various as­pects of muscle cell function. [7],[8],[9],[10] Vitamin D deficiency is associated with decreased muscle size [11],[12],[13] and strength, [14],[15] particularly in the large extensor and flexor muscles of the lower limbs, [15] which by itself result in reduced phy­sical activity and increased falls in the el­derly. [14] There is an evidence that these deficits can be improved by vitamin D supplemen­tation. [15]

The level of 1,25 dihydroxy vitamin D (1,25 (OH) 2 D) begins to decline early in the course of chronic kidney disease (CKD), [16] owing to the decline in proximal tubular production of 1 α-hydroxylase, resulting in the development of secondary hyper-parathyroidism. [16],[17],[18],[19]

In addition to 1,25(OH) 2 D, uremic patients may also have 25-hydroxy vitamin D (25-OHD) deficiency. 25-OHD deficiency causes muscle dysfunction in non-uremic patients, [20],[21],[22],[23],[24] but the effect on muscle function in uremic patients is not well known.

In the recent studies, evaluation of muscle function have been performed by magnetic resonance imaging (MRI), EMG and ques­tionnaires. MRI T1 (1.5 Tesla) measures the muscle size. [25],[26] There are 36 questions in the questionnaire about physical functions that will be filled out based on the patients' state­ments. [27] Methods of evaluation for physical performance are as follows:

  1. Gait speed (walking a distance of 20 feet at a comfortable walking pace and again at their maximal speed).
  2. The 6-min walk (walking for 6 min at maximal speed). [28]
  3. Sit-to-stand time (sitting in a chair of stan­dard height and stand up completely and repeating for ten times). [29]
  4. Static balance (standing on one leg for up to 30 s and repeating it with the other leg). [30]

Evaluation of muscle strength is performed by assessing isotonic, isokinetic and isometric strength of the flexor and extensor muscles of the knee and ankle dorsiflexor muscles (tibialis anterior). [31]

The technique of manual muscle testing (MMT), a system for grading the strength of muscles, began with Lovett in 1912. [32],[33] Using the MMT for disability evaluation in polio and other neuromuscular disease was presented in 1936. [33] MMT may be a tool for measuring the neuromuscular dysfunction and changes occur­ring in the treatment process. The data show that it is better to use MMT as an adjunct rather than as an alternative to other standard diagnostic measures. [34],[35] The study carried out in 2008 by Walter H. Schmitt Jr et al suggests that there are some factors that may affect the outcome of MMT, for example the number of muscles being examined, tester's hand contact and tester's body position. They recommend guidelines to increase the accuracy of MMT. [36] Now, we can use micro manual muscle tester (MMMT) as an alternative to the MMT.

MMMT is a digital instrument that measures muscle force in kilograms. MMMT measures peak force, time to reach peak force and total test time. MMMT is performed with the clini­cian applying force to the limb of a patient. The objective of the test is for the clinician to overcome or "break" the patient resistance. The MMMT records the peak force and the time required to achieve the "break," providing reliable, accurate and stable muscle strength readings that confirm to most manual muscle testing protocol.

Because most of the ESRD patients in Iran are not physically fit to perform MMT, and we do not have modern MRI equipments, we used the MMMT, which has not been practiced in Iran before.

   Materials and Methods Top

This cross-sectional study was performed from May until September 2012 in hemo-dialysis centers of the Loghman Hakim Hospital and Ashrafi Esfahani Hospital in Tehran, Iran. Men and women undergoing maintenance hemodialysis three times per week (4 h each time) were eligible to participate in this study.

Inclusion criteria were adequate dialysis deli­very with KT/V ≥1.2 and good compliance with dialysis treatment (not missing more than two dialysis treatments in the month), age ≥15 years and serum albumin ≥3.5 g/dL. Those pa­tients who had been on dialysis for less than three months or had reasons to be in a cata-bolic state (including HIV, malignancy, infec­tion requiring intravenous antibiotic within two months prior to enrollment) were excluded from the study.

KT/v was calculated by a software. Calcium (Ca), phosphorous (p), 25-OHD (ng/mL), albu­min (g/dL), C-reactive protein (CRP) (quan­tities) (mg/dL), parathyroid hormone (pg/L, hemogolobin, platelets and white cell count have all been tested in a single laboratory before dialysis. All data like body mass index (BMI), etiology of CKD, diabetes, etc has been saved. Muscle force of the lower extremity of all patients was measured with an MMMT by a single physician.

In this method, the day after hemodialysis, the patient is made to sit on a chair. The physician then places the MMMT on the lower one-third of the patient's leg (one of the legs) and asks the patient to push his leg up against physician resistance. The instrument records the patient muscle force after 15 s. The phy­sician examines both legs and take the average of both readings.

The study participants were divided into three groups based on the muscle force:

  1. Weak: Decreased muscle force (<5 kg).
  2. Normal: Normal muscle force (5-10 kg).
  3. Strong: Strong muscle force (>10 kg).

Statistical analyses were performed using SPSS version 16. Using descriptive statistics, we evaluated the mean and standard deviation and, according to inferential statistics, we cal­culated chi-square and crosstabs.

   Results Top

In this study, we examined 135 patients, including 69 male (51%) and 66 female (69%) (mean: 1.4, standard deviation: 0.5) patients. The patients were divided into two groups: The first group included 21 patients (16%) aged 15-45 years and the second group included 114 pa­tients (84%) aged 45-85 years (mean: 1.84, standard deviation: 0.36). Of these 135 pa­tients, 59 cases (44%) had diabetes.

Based on the result of BMI, the patients were classified into the following five groups:

  1. Thirteen patients (10%) having below-nor­mal BMI (15-20).
  2. Seventy patients (52%) having normal BMI (20-25).
  3. Thirty-two patients (24%) having upper-normal BMI (25-30).
  4. Nineteen patients (14%) having BMI >30 (obesity).
  5. One patient (0.7%) having BMI >40 (severe obesity) (mean: 2.4, standard deviation: 0.87).

Based on the results of the 25-OHD level, patients were classified into three groups:

  1. Eighty-five patients (63%) had 25-OHD deficiency (25-OHD <30)
  2. Forty-three patients (32%) had a normal level of 25-OHD (30-70)
  3. Seven patients (5%) had a toxic level of 25-OHD (>70) (mean: 1.42, standard deviation: 0.59).

As per the result of calcium level, 26 patients (19%) had Ca <8, 99 patients (73%) had a nor­mal level of Ca (8-10) and 10 patients (7%) had Ca >10 (mean: 1.88, standard deviation: 0.5).

We excluded three patients due to amputation below the knee in one limb. Considering lower extremity muscle force, we put the patients into three different groups. Eighty-four pa­tients (62%) had weak muscle power (<5 kg), 46 patients (34%) had normal muscle power (5-10 kg) and three patients (21%) had strong muscle power (>10 kg) (mean: 1.39, standard deviation: 0.53). A significant relation has been found between 25-OHD level and muscle force [Chi-square: (4,133) = 10.75 (P = 0.02)] [Table 1], between age and muscle force [chi-square: (2,135) = 12.838 (P = 0.002)]. In addition to the above, a significant relation has been noticed between gender and muscle force. [Chi-square: (2,133) = 19.22 (P <0.001)]. However, the relationship between serum level of Para­thyroid hormone (PTH and muscle force was not significant.
Table 1: Result of lower extremity force in relation to 25-OHD.

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It is well known that 1, 25(OH) 2 D deficiency is common in ESRD patients due to lack of 1α-hydroxylase activity. Vitamin D deficiency along with other causes such as uremia, in­flammation and malnutrition are major causes of muscle wasting in the ESRD population.

In 2012, Gordon et al carried out a study by evaluating 26 patients and found that 73% of them had 25-OHD deficiency. The level of 1,25(OH) 2 D was also low in those patients, and there was a correlation between level of 1,25 (OH) [2] D with muscle size and physical activity. [26] Another study performed by Heaf et al on 21 patients shows that 25-OHD defi­ciency is common in uremic patients, but there is no correlation between level of 25-OHD and physical activity. [27]

Our study shows that the prevalence of 25-OHD deficiency is high in ESRD patients (63%), which agrees with the recent studies. In our study, there was significant relation bet­ween serum level of 25-OHD and muscle force that is different from the 2012 study by Heaf et al. They evaluated 21 patients using EMG, questionnaire and chair-stand test, whereas Gordon et al evaluated their patients using MRI, static balance and 6-min walk.

The main differences of our study from those of others are: First, we carried out the test on a larger group, which increases the accuracy of the test. Second, we did not use EMG for eva­luating our patients, because diabetes is the most common cause of ESRD in Iran and also in our study. We should also note that the accu­racy of the EMG test is low in diabetes. Third, we used MMMT for evaluating muscle force. The test could be repeated and the result recorded would be useful for follow-up of the patient. We suggest to take the benefit of the MMMT method in line with other methods like MRI and questionnaire.

We found a significant relation between age, gender and muscle power, as is normally expected. We already know that men have more muscle bulk and that muscle wasting is more common in the elderly.

In hemodialysis patients, 25-OHD supple­mentation not only stimulates 1,25(OH) 2 D pro­duction but is also advantageous in providing a substrate for extrarenal effects of 25-OHD independent of renal function and renal 1α-hydroxylase activity in severe uremia. [37],[38],[39] Thus, a normal level of 25-OHD may be im­portant even in the absence of 1α-hydroxylase activity, and indeed low 25-OHD is associated with excess mortality in hemodialysis patients.

Considering the result of our research, which indicates significant relations between 25OH-D deficiency and muscle power in the ESRD population, we suggest to treat the 25-OHD deficiency of the patients and to evaluate the post-treatment muscle power. [40]

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Correspondence Address:
Dr. Nargesosadat Zahed
Department of Nephrology, Loghmanhakim Hospital, Shahid Beheshti University, Tehran
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DOI: 10.4103/1319-2442.139885

PMID: 25193897

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