Distribution of serum creatine kinase activity in young healthy persons

Creatine kinase serum levels in children revisited: New reference intervals from a large cohort of healthy children and adolescents

BACKGROUND

Creatine Kinase (CK) has become increasingly important in pediatrics as a commonly used laboratory screening parameter for neuromuscular diseases. Recent research suggests that hyperCKemia in children is not always associated with pathology and can occur due to several reasons. Little is known of various clinical factors that may influence CK throughout child development.

OBJECTIVE

This study aimed to establish reliable age- and sex-specific reference ranges for serum CK levels in healthy infants, children, and adolescents. In addition, the effect of puberty, oral contraceptive (OC) use as well as steroid hormones on CK was examined.

MATERIALS AND METHODS

The data was collected from subjects of the longitudinal population-based "LIFE Child"-cohort between 2011 and 2016 in Leipzig, Germany. 5238 blood samples of 2707 healthy children, aged between 0.14 months and 18 years, were analyzed.

RESULTS

Serum CK levels raised during the first year of life, peaking shortly after age one (P50girls = 2.7 µkat/L, P50boys = 2.90 µkat/L). There was a pronounced difference in the 97.5th percentile between boys and girls during adolescence with its maximum at age 18 (P97.5girls = 5.74 µkat/L, P97.5boys= 14.48 µkat/L). Also, mean CK serum levels were significantly higher in boys (bboys = 0.29, pboys < 0.001). Intake of oral contraceptives (OC), extreme underweight, underweight and obesity revealed a significant inverse correlation with CK serum levels.

CONCLUSION

Age, sex, OC intake and weight status affect serum CK levels, particularly during infancy and puberty. We recommend the use of age- and sex-specific reference values for CK serum levels to assess the clinical relevance of measurements.

Characterization of Creatine Kinase Levels in Tofacitinib-Treated Patients with Ulcerative Colitis: Results from Clinical Trials

BACKGROUND

Tofacitinib is an oral, small-molecule JAK inhibitor for the treatment of ulcerative colitis (UC). Creatine kinase (CK) levels and CK-related adverse events (AEs) in tofacitinib-treated patients with UC were evaluated.

METHODS

Data were analyzed for three UC cohorts: Induction (phase 2 and 3 induction studies); Maintenance (phase 3 maintenance study); Overall [patients who received tofacitinib 5 or 10 mg twice daily (b.d.) in phase 2, phase 3, or open-label, long-term extension studies; data at November 2017]. Clinical trial data for tofacitinib-treated patients with rheumatoid arthritis, psoriasis, and psoriatic arthritis are presented for contextualization.

RESULTS

Week 8 mean change from baseline CK with tofacitinib 10 mg b.d. induction therapy was 91.1 U/L (95% CI, 48.1-134.1) versus 19.2 U/L (8.5-29.9) with placebo. Among patients completing induction with 10 mg b.d. and re-randomized to 52 weeks of maintenance therapy, mean increases from induction baseline to the end of maintenance were 35.9 (8.1-63.7), 90.3 (51.9-128.7), and 115.6 U/L (91.6-139.7), with placebo, 5 and 10 mg b.d., respectively. The incidence rate (unique patients with events per 100 patient-years) for AEs of CK elevation in the tofacitinib-treated UC Overall cohort was 6.6 versus 2.2, 6.5, and 3.7 for tofacitinib-treated patients with rheumatoid arthritis, psoriasis, and psoriatic arthritis, respectively. No serious AEs of CK elevation or AEs of myopathy occurred in UC studies.

CONCLUSIONS

In patients with UC, CK elevations with tofacitinib appeared reversible and not associated with clinically significant AEs. UC findings were consistent with tofacitinib use in other inflammatory diseases.

TRIAL REGISTRATION

NCT00787202; NCT01465763; NCT01458951; NCT01458574; NCT01470612; NCT01262118; NCT01484561; NCT00147498; NCT00413660; NCT00550446; NCT00603512; NCT00687193; NCT01059864; NCT01164579; NCT00976599; NCT01359150; NCT02147587; NCT00960440; NCT00847613; NCT00814307; NCT00856544; NCT00853385; NCT01039688; NCT02187055; NCT00413699; NCT00661661; NCT01710046; NCT00678210; NCT01276639; NCT01309737; NCT01241591; NCT01186744; NCT01163253; NCT01877668; NCT01882439; NCT01976364.

Is it necessary to adjust current creatine kinase reference ranges to reflect levels found in professional footballers?

Objective

We aimed to explore the validity of applying current reference ranges of the enzyme creatine kinase (CK) when analysing the medical status of professional footballers and to offer a more functional CK reference range for professional footballers.

Methods

A sample of 27 professional male footballers competing in The Football League Championship was analysed. The single sample Wilcoxon signed-rank test was used to compare the CK distribution of the study group with that of a control group of military personnel reported in the literature.

Results

The median values for study group and the published control group were 284 U/L and 124 U/L, respectively (P<0.001) suggesting that the average CK activity of professional footballers is higher than that of the normal healthy military population.

Conclusion

Ethnicity, sex, age and physical exercise are factors that likely influence CK levels among various populations. From our analysis, we recommend a new 95% reference interval of 64.9 U/L to 1971.7 U/L for professional footballers.

Approach to asymptomatic creatine kinase elevation

How to manage a patient who has an elevated serum creatine kinase (CK) level but no or insignificant muscle-related signs and symptoms is a clinical conundrum. The authors provide a systematic approach, including repeat testing after a period of rest, defining higher thresholds over which pursuing a diagnosis is worthwhile, and evaluating for a variety of nonneuromuscular causes. They also outline a workup for neuromuscular causes.

Statins and the neuromuscular system: a neurologist's perspective

Statins intolerance is mainly due to their side effects on the neuromuscular system (primarily muscle). It has become an important issue because of the major cardiovascular risk reduction of this class of drugs. However, the facts related to these side effects are sometimes under-recognized or controversial. A literature review of the recent developments in the field is given. The clinical definition of statin myopathy and its presentation are not suitable for the myology field. Management and prevention are not validated. More genetic risk factors need to be established. Neurologists should become more involved in statin intolerance evaluation and management.

Influence of glucose-lowering rate on CKMB and myoglobin serum levels in type-2 diabetes patients with coronary heart disease

OBJECTIVE

To analyze the level of creatine kinase isoenzyme (CKMB), myoglobin, to explore the influence of different glucose-lowering rate on cardiac enzyme in type 2 diabetes mellitus patients with coronary heart disease (T2DMC), to search for the rational glucose-lowering rate.

METHODS

A total number of 293 type 2 diabetic patients who were hospitalized in the First Affiliated Hospital of Harbin Medical University from May 2008 to December 2009 were recruited. Two groups were divided according to the coronary angiography. 142 subjects of type 2 diabetes mellitus (T2DM) and 151 subjects of T2DMC received intensive glucose therapy. After CKMB and myoglobin being measured, variation and correlation factors were evaluated.

RESULTS

In T2DM group, the level of CKMB was significantly lower at follow-up than that before intensive therapy. Then, we got four subgroups according to the glucose-lowering rate. In T2DM group, when the fasting or postprandial glucose-lowering rate was no more than 6 mmolL(-1)d(-1), the level of CKMB and myoglobin were significantly lower than that before intensive therapy (P<0.05). When the fasting glucose-lowering rate is faster than 6 mmolL(-1)d(-1), the level of CKMB is significantly higher after intensive therapy than that before glucose-lowering (P<0.05). In T2DMC group, when the fasting or postprandial glucose-lowering rate was not more than 4 mmolL(-1)d(-1), the level of CKMB and myoglobin was significantly lower than that before intensive therapy (P<0.05, P<0.01). When the fasting glucose-lowering rate was faster than 4 mmolL(-1)d(-1), the level of CKMB and myoglobin was significantly higher at follow-up than that before intensive therapy (P<0.05). Before intensive therapy, high density lipoprotein cholesterol (HDL-C) has a negative linear regression relationship with CKMB (P<0.01). Low density lipoprotein cholesterol (LDL-C) and triglyceride (TG) and glycosylated hemoglobin A1c (HbA1c) have a positive linear regression relationship with CKMB (P<0.05). HDL-C has a negative linear regression relationship with myoglobin (P<0.01). LDL-C and TG have a positive linear regression relationship with myoglobin (P<0.01).

CONCLUSIONS

T2DM patients, no matter with CHD or not, all have a rational fasting glucose-lowering rate; the fasting glucose-lowering rate is more susceptible to myocardial damage anticipation than the postprandial glucose-lowering rate.

Statin-induced rhabdomyolysis: a comprehensive review of case reports

PURPOSE

To identify case reports of statin-induced rhabdomyolysis and summarize common predisposing factors, symptoms, diagnostic findings, functional outcomes, characteristics, treatment, and rehabilitation.

METHOD

MEDLINE, CINAHL, SCOPUS, and PEDro databases were searched (1990-2013) for relevant case reports using the search terms "Statins," "Rhabdomyolysis," "Myalgia," "Muscle damage," "Muscle injury," and "Myopathy." Relevance (based on title and abstract) was assessed by one investigator; two investigators independently reviewed the relevant articles to determine inclusion in the review.

RESULTS

A total of 112 cases met the inclusion criteria. The majority were in men (70%) and people over 45 years of age (mean 64 [SD 14] years). Simvastatin was the most commonly reported statin (n=55); the majority of cases reported the use of concomitant medications such as fibrates (n=25). Weakness (n=65) and muscle pain (n=64) were the most common symptoms. In 19 cases, the patient was referred to rehabilitation, but the case reports do not include descriptions of the treatment.

CONCLUSION

Statin-induced rhabdomyolysis was more commonly reported when statins were used in conjunction with other drugs, which potentiated its effect. Research is needed to identify the role of exercise and rehabilitation following statin-induced rhabdomyoloysis since muscle damage may be severe and may have long-term effects on muscle function.

Effects of statins on skeletal muscle: a perspective for physical therapists

Hyperlipidemia, also known as high blood cholesterol, is a cardiovascular health risk that affects more than one third of adults in the United States. Statins are commonly prescribed and successful lipid-lowering medications that reduce the risks associated with cardiovascular disease. The side effects most commonly associated with statin use involve muscle cramping, soreness, fatigue, weakness, and, in rare cases, rapid muscle breakdown that can lead to death. Often, these side effects can become apparent during or after strenuous bouts of exercise. Although the mechanisms by which statins affect muscle performance are not entirely understood, recent research has identified some common causative factors. As musculoskeletal and exercise specialists, physical therapists have a unique opportunity to identify adverse effects related to statin use. The purposes of this perspective article are: (1) to review the metabolism and mechanisms of actions of statins, (2) to discuss the effects of statins on skeletal muscle function, (3) to detail the clinical presentation of statin-induced myopathies, (4) to outline the testing used to diagnose statin-induced myopathies, and (5) to introduce a role for the physical therapist for the screening and detection of suspected statin-induced skeletal muscle myopathy.

Should high creatine kinase discourage the initiation or continuance of statins for the treatment of hypercholesterolemia?

Patients with high low-density lipoprotein cholesterol (LDLC) and asymptomatic high creatine kinase (CK) (>or=250 but <2500 IU/L, 10x the laboratory upper normal limit [UNL]) are often not started on statins or have statins stopped because of concern about myositis-rhabdomyolysis. In the current report, we prospectively examined the hypothesis that asymptomatic patients with high CK (>or=250 but <2500 IU/L) tolerate statins well at doses reducing LDLC to target, less than 100 mg/dL, without development of myalgia-myositis. We assessed outcomes of 3 groups of patients referred to us because of asymptomatic high CK (>or=250 but <2500 IU/L)--1 group (n = 29) on statins at referral and continued on statins, 1 group (n = 20) not on statins and started on statins, and 1 group (n = 19) not on statins and not given statins--all restudied 1 month after entry and then every 3 months. Of the 68 patients, 59 (87%) had CK greater than 1 to 3 times the UNL, 7 (10%) had CK greater than 3 to 5 times the UNL, and 2 (3%) had CK greater than 5 to 10 times the UNL. After 1.2 months of follow-up in 29 statin-->statin patients, median CK fell from 353 to 301 (P = .0018) and was 287 (P = .015) after 4 months. After 1.3 months of follow-up in 20 no statin-->statin patients, median CK fell from 397 to 292 (P = .0094) and was 419 after 4.1 months. After 1.1 months of follow-up in 19 no statin-->no statin patients, median CK fell from 392 to 323 (P = .14) and was 271 (P = .029) after 4.2 months. By repeated-measures analysis, there were no differences in entry CK among the 3 treatment groups; CK fell (P = .04) in the no statin-->no statin patients. Despite high baseline CK (48 patients with CK 1-5x the UNL, 1 with CK 5-10x UNL), no patients during follow-up on statins developed CK greater than 10 times the UNL (2500 IU/L), none discontinued statins or reduced statin dose because of myalgia-myositis, and there was no rhabdomyolysis. High pretreatment CK, particularly 1 to 5 times the UNL, should not be an impediment to start or continue statins to lower LDLC.

The upper values of plasma creatine kinase of professional soccer players during the Brazilian National Championship

The current schedule of the Brazilian Soccer Championship may not give players enough recovery time between games. This could increase the chances of muscle damage and impaired performance. We hypothesized that plasma creatine kinase (CK) activity could be a reliable indirect marker of muscle overload in soccer players, so we sought to identify the reference values for upper limits of CK activity during a real-life elite competition. This study analyzed changes in plasma CK activity in 128 professional soccer players at different times during the Brazilian Championship. The upper limits of the 97.5th and 90th percentiles determined for CK activity were 1.338U/L and 975U/L, respectively, markedly higher than values previously reported in the literature. We also evaluated a team monthly throughout the Championship. The upper limit of the 90th percentile, 975U/L, was taken as the decision limit. Six players showing plasma CK values higher than this were asked to decrease their training for 1 week. These players presented lower CK values afterwards. Only one player with a CK value higher than the decision limit (1800U/L 1 day before a game) played on the field and was unfortunately injured during the game. The CK activity in all the other players showed a significant decrease over the course of the Championship, and the values became more homogeneous at the end. The results presented here suggest that plasma CK upper limit values can be used as a practical alternative for early detection of muscle overload in competing soccer players.

Distribution of creatine kinase in the general population: implications for statin therapy

BACKGROUND

Eligible subjects with mildly elevated serum creatine kinase (CK) activity are often excluded before randomization in statin trials, but patients may potentially be misclassified as having hyperCKemia when inappropriate reference limits are used. Little information is usually given regarding how reference limit data were established, although evidence suggests that the variation of CK activity in the general population is wider than reflected in reference intervals in current use.

METHODS

We determined reference intervals for serum CK according to National Committee on Clinical Laboratory Standards/Nordic Reference Interval Project guidelines, in a stratified random sample of the population, including 1444 individuals, aged 34 to 60 years, after 3 days of rest. Participants were mainly of white European (n = 503), South Asian (n = 292), or African descent (n = 580).

RESULTS

The calculated upper reference limits (97.5th percentile) for nonblack and black women and men were 2 to 5 times higher than recommended by the assay manufacturer. Respectively 13% of the white Europeans, 23% of South Asians, and 49% of the black people had serum CK activities above the manufacturer-provided limits.

CONCLUSION

The variation in CK activity within the population is wider than previously suggested in smaller, nonrandom samples, and relatively high values occur frequently in all subgroups studied after rest. Therefore, we infer that upward adjustment of the upper reference limit is necessary for all population subgroups studied. The use of appropriately established reference intervals may improve the use of statins and particularly benefit the control of dyslipidemia in those with relatively high baseline CK activity.

Reference intervals for serum creatine kinase in athletes

BACKGROUND

The serum concentration of creatine kinase (CK) is used widely as an index of skeletal muscle fibre damage in sport and exercise. Since athletes have higher CK values than non-athletes, comparing the values of athletes to the normal values established in non-athletes is pointless. The purpose of this study was to introduce reference intervals for CK in athletes.

METHOD

CK was assayed in serum samples from 483 male athletes and 245 female athletes, aged 7-44. Samples had been obtained throughout the training and competition period. For comparison, CK was also assayed in a smaller number of non-athletes. Reference intervals (2.5th to 97.5th percentile) were calculated by the non-parametric method.

RESULTS

The reference intervals were 82-1083 U/L (37 degrees C) in male and 47-513 U/L in female athletes. The upper reference limits were twice the limits reported for moderately active non-athletes in the literature or calculated in the non-athletes in this study. The upper limits were up to six times higher than the limits reported for inactive individuals in the literature. When reference intervals were calculated specifically in male football (soccer) players and swimmers, a threefold difference in the upper reference limit was found (1492 vs 523 U/L, respectively), probably resulting from the different training and competition demands of the two sports.

CONCLUSION

Sport training and competition have profound effects on the reference intervals for serum CK. Introducing sport-specific reference intervals may help to avoid misinterpretation of high values and to optimise training.

The bootstrap: a technique for data-driven statistics. Using computer-intensive analyses to explore experimental data

BACKGROUND

The concept of resampling data--more commonly referred to as bootstrapping--has been in use for more than three decades. Bootstrapping has considerable theoretical advantages when it is applied to non-Gaussian data. Most of the published literature is concerned with the mathematical aspects of the bootstrap but increasingly this technique is being utilized in medical and other fields.

METHODS

I reviewed the published literature following a 1994 publication assessing the transfer of technology, including the bootstrap, to the biomedical literature.

RESULTS

In the ten-year period following that 1994 paper there were 1679 published references to the technique in Medline. In that same time period the following citations were found in the four major medical journals-British Medical Journal (48), JAMA (51), Lancet (52) and the New England Journal of Medicine (45).

CONTENT

I introduce the basic theory of the bootstrap, the jackknife, and permutation tests. The bootstrap is used to estimate the accuracy of an estimator such as the standard error, a confidence interval, or the bias of an estimator. The technique may be useful for analysing smallish expensive-to-collect data sets where prior information is sparse, distributional assumptions are unclear, and where further data may be difficult to acquire. Some of the elementary uses of bootstrapping are illustrated by considering the calculation of confidence intervals such as for reference ranges or for experimental data findings, hypothesis testing such as comparing experimental findings, linear regression, and correlation when studying association and prediction of variables, non-linear regression such as used in immunoassay techniques, and ROC curve processing.

CONCLUSIONS

These techniques can supplement current nonparametric statistical methods and should be included, where appropriate, in the armamentarium of data processing methodologies.

The effect of creatine supplementation upon inflammatory and muscle soreness markers after a 30km race

We have evaluated the effect of a creatine supplementation protocol upon inflammatory and muscle soreness markers: creatine kinase (CK), lactate dehydrogenase (LDH), prostaglandin E2) (PGE2) and tumor necrosis factor-alpha (TNF-alpha) after running 30km. Runners with previously experience in running marathons, with their personal best between 2.5-3h were supplemented for 5 days prior to the 30km race with 4 doses of 5g of creatine and 15g of maltodextrine per day while the control group received the same amount of maltodextrine. Pre-race blood samples were collected immediately before running the 30km, and 24h after the end of the test (the post-race samples). After the test, athletes from the control group presented an increase in plasma CK (4.4-fold), LDH (43%), PGE2 6.6-fold) and TNF-alpha (2.34-fold) concentrations, indicating a high level of cell injury and inflammation. Creatine supplementation attenuated the changes observed for CK (by 19%), PGE2 and TNF-alpha (by 60.9% and 33.7%, respectively, p<0.05) and abolished the increase in LDH plasma concentration observed after running 30km, The athletes did not present any side effects such as cramping, dehydration or diarrhea, neither during the period of supplementation, nor during the 30km race. All the athletes finished the race in a time equivalent to their personal best +/- 5.8%. These results indicate that creatine supplementation reduced cell damage and inflammation after an exhaustive intense race.

Drug-induced myopathies

Two major entities continue to be controversial in the field of clinical myotoxicity: the various myopathies that are induced by the cholesterol-lowering agents and the acute quadriplegic myopathy of intensive care. Both conditions are relatively common, but their pathogenesis is unclear. The problematic issues related to these disorders are presented, with suggested topics for future research.