Official Journals By StatPerson Publication
Table of Content - Volume 4 Issue 1 - October2017
Levels of serum creatine phosphokinase in thyroid disorders
Priyanka Vaitla1, Sarada Munagavalasa2*, N Vani3
1Resident specialist, Department of Biochemistry,3Professor and HOD, Osmania Medical College, Hyderabad, Telangana, INDIA. 2Assistant Professor, Modern Government Maternity Hospital, Hyderabad, Telangana, INDIA. Email: saradamunagavalasa1@gmail.com
Abstract Objective: The alteration in serum levels of triiodothyroinine (T3) and thyroxine (T4) in thyroid disorders is well established. Few studies have emphasized the role of serum creatine phosphokinase in thyroid disorders and its use as a marker in these disorders which is not well established. The present study was conducted to assess the level ofserum creatine phosphokinase in thyroid disorders Methods: A case control study was done with 100 patients with thyroid disorder. triiodothyroinine (T3), thyroxine (T4), thyroid stimulating hormone (TSH) and serum creatine phosphokinase (CPK) were measured. Results: Serum CPK levelswerefound to behigher in hypothyroid patients compare to healthy control. In contrast serum CPK levels in Hyperthyroid patients is significantly decreased compare to controls Interpretations and conclusion : Serum levels of T3 and CPK have an inverse relation in thyroiddisorders and the estimation of CPK levels will be extremely valuable as an alternate marker for diagnosing. Hypothyroid and Hyperthyroid patients. Keywords: Hypothyroid patients, Hyperthyroid patients, serum creatine phosphokinase
INTRODUCTION Dysfunction and anatomical abnormalities of the thyroid are among the most common diseases of the endocrine glands1. Thyroid gland secretes thyroxine (T4) and triidothyronine (T3) which play a critical role in cell differentiation during development and help to maintain thermogenic and metabolic homeostasis in adults. Production of these hormones is regulated by TSH and thyrotropin releasing hormones. In hypothyroidism there will be low T3 and T4 associated with high circulating TSH levels and in Hyperthyroidism there will be excess circulating free T3 and T4 with supressed TSH levels. Out of these TSH has been accepted as the initial screening test. However, the abnormal TSH level necessitates the use of other indicators of thyroid status including total and FT3 and T4. None of these parameters have proven to be ideal as their measured levels tend to vary in conditions like pregnancy, use of oral contraceptives, protein wasting diseases, liver disease, certain drugs and heparin, etc.2 The inherent limitations of these parameters necessitate the establishment of alternate markers and enzymes like transaminases, lactate dehydrogenase (LDH) and creatine kinase (CK). Among these, CK has shown promising results as a diagnostic tool for thyroid disease. These disorders are common in women than in men at all ages3. In recent years studies have been conducted to establish a relationship between creatine phosphokinase and thyroid disorders4, 5. A majority of patients with hypothyroidism have been shown to have increased serum CPK. Few studies have concluded that serum enzyme activities which are derived from muscle such as CPK, AST, ALT, amylase, alkaline phosphatase and LDH are elevated in thyroid dysfunction. They also mentioned the presence of hypercholesterolemia and hypertriglyceridemia in hypothyroidism6, 7. Mere elevation of CPK, serum cholesterol and triglycerides in hypothyroidism are rarely useful diagnostically. However obtaining serum TSH levels and thereby making a diagnosis of hypothyroidism may explain elevation of CPK, cholesterol and triglycerides. Hence, the present study was carried out to establish relationship of serum CPK levels with T3, T4 and TSH in Hypothyroid and Hyperthyroid patients which can lead to usage of CPK as an alternate marker in diagnosis of thyroid disorders.
MATERIALS AND METHODS A case control study was conducted in the Department of Biochemistry, Osmania General Hospital, Hyderabad. The study was conducted over a period of one year. 150 thyroid dysfunction patients and controls were included in the study. The cases and samples were collected from Department of Endocrinology, Osmania General Hospital. Investigations were performed at the Department of Biochemistry, Osmania Medical College/Osmania General Hospital, Hyderabad. Inclusion criteria Group 1 included healthy controls who were matched for age and sex. Group 2 included those individuals with diagnosed with Hypothyroidism Group 3 included those individuals with diagnosed with Hyperthyroidism Exclusion criteria Excluded other causes which alter the CK levels
Data collection Proforma including age, sex, medical history, onset and duration of thyroid disorder was filled. Physical examination was done measuring height, weight, waist circumference was recorded. Fasting venous blood sample was collected from all the subjects. Laboratory parameters including T3, T4, TSH and CPK levels were estimated in the samples. The data was analyzed using GraphPad Prism software version 6.0. Descriptive results are expressed as mean and SD of various parameters in different groups. to assess the significance of the differences observed in the mean values of different parameters observed in different groups studied, the data is subjected to ANOVA test. The significance of difference of mean values of different groups and within the groups is represented by p values and p value ˂0.05 is considered as significant. OBSERVATION AND RESULTS Serum CPK was significantly higher in cases with low T3 and T4 compared to controls (p<0.001). In group 2, Serum CPK values were found to be elevated in hypothyroid patients compared to healthy individuals with a p<0.001. In group 3, CPK was negatively correlated with T3 and T4 but was not statistically significant with a p value < 0.05 Table 3. Results show that serum CPK levels increased significantly in hypothyroid patients. There was also a correlation observed between CPK and thyroid hormones in hyperthyroid patients but it was not significant.
Table 1: Showing mean, SD, SEM and P value of Hypothyroid group
Table 2: Showing mean, SD, SEM and P value of Hyperthyroid group
Table 3: Showing comparison of levels of serum creatine phosphokinase in controls, hypothyroid patients and hyperthyroid patients.
DISCUSSION The study was done to evaluate the role of CPK in individuals with thyroid disorders. The results of this study confirm that elevated serum CPK levels is frequently found in hypothyroidism and decreased in hyperthyroidism. According to our study, the CPK levels also correlated with the degrees of hypothyroidism and hyperthyroidism, as evident by the magnitude of the TSH. These findings are in accordance with those of other studies, which report a 43% to 97% elevation of serum CK activity in hypothyroidism: Beyer et al, 43%8, Giampietro et al, 90%9 and Soufir et al,10 97%. This is in contrast to the findings of Hartl et al, who found an elevation of CK activity in only 2 of its patients11. The CPK levels were found to be decreased in hyperthyroid cases compared to controls. This of decreased CPK levels in patients with hyperthyroidism compared with controls is in accordance with other studies12, 13. Hekimsoy et al in a study conducted in 2005, found that skeletal muscle in overt hypothyroidism is affected more compared to subclinical hypothyroidism. They also found that there was a positive correlation between CK and TSH (r = 0.432;p = 0.04), a negative correlation between FT3 and CK (r = –0.556, p = 0.002)14. Giampietro et al in 1984, suggested that myoglobin and CK are the best indicators of hypothyroid myopathy, since they are sensitive for the early detection of muscle involvement due to metabolic disorder and are closely correlated to the metabolic condition of patients.9 Different mechanisms have been proposed to cause elevated CPK activity in hypothyroidism, although these mechanisms may have varying influence at different stages of the disease15. Hypothyroidism leads to a hypo-metabolic state which can cause a reduction in glycolysis and oxidative phosphorylations and thus reducing adenosine triphosphate (ATP) concentrations beyond a critical limit. Increased cell permeability and the leakage of CK from cells can also be caused due to alteration in sarcolemmal membranes.16, 17. Another possibility is that because of hypothyroidism there occurs a reduced turnover of CK allowing serum activities to rise generating a marked release of CK through the altered sarcolemnalmembranes18. Some authors suggest direct role of T3 at the regulation of gene expression. It has been shown to induce or repress production of different proteins by increasing or decreasing transcription.19, 20 The lower levels of CK activity in hyperthyroidism may be due to the hypermetabolic state which inturn may increase enzyme degradation, which may have contributed to these low CK activity.
CONCLUSION It is clear from the results of the present study that increased serum CPK levels are associated with Hypothyroidism. Though we recommend further studies in this regard, we suggest that serum CPK can be used as an alternate and supportive marker for the diagnosis of Hpothyroidism.
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