Hyper-CK-aemia revisited

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.

A Neuromuscular Approach to Statin-Related Myotoxicity

Approximately 95% of statin-treated patients tolerate this form of cholesterol management without any adverse effects. However, given their efficacy in reducing low density lipoproteins and cardiovascular events large numbers of patients are selected for statin therapy. Therefore muscle complications are, in fact, quite common. Limited understanding of the underlying pathophysiology has hampered physicians' ability to identify patients at risk for developing statin myotoxicity. A growing number of published case reports/series have implicated statins in the exacerbation of both acquired and genetic myopathies. A clinical management algorithm is presented which outlines a variety of co-morbidities which can potentiate the adverse effects of statins on muscle. In addition, a rational approach to the selection of those patients most likely to benefit from skeletal muscle biopsy is discussed. Ongoing work will define the extent to which statin-intolerant patients represent carriers of recessive metabolic myopathies or pre-symptomatic acquired myopathies. The expanding importance of pharmacogenomics will undoubtedly be realized in the field of statin myopathy research within the next few years. Such critical information is needed to establish more definitive management and diagnostic strategies.

A Japanese child with asymptomatic elevation of serum creatine kinase shows PTRF-CAVIN mutation matching with congenital generalized lipodystrophy type 4

Congenital generalized lipodystrophy (CGL), characterized by generalized absence of adipose tissue, has heterogeneous causes. Recently, a novel type of CGL complicated by muscular dystrophy was categorized as CGL4 caused by PTRF-CAVIN deficiency. However, it is unknown whether CGL4 exhibits clinical abnormalities during the infantile period. Here, we describe the youngest Japanese case of CGL4-a Japanese girl with asymptomatic high serum creatine kinase (CK) levels at 3months old. She was referred to our hospital at 5months of age because of her elevated serum CK (2528IU/L). Generalized absence of adipose tissue was first recognized at 2years of age. Mutation analysis of genes known to be responsible for CGL1-3 failed to disclose any abnormalities. Instead, analysis of the PTRF-CAVIN gene encoding PTRF-CAVIN revealed compound heterozygous mutations, one allele contained an insertion (c.696_697insC) and the other allele harbored a novel nonsense mutation (c.512C>A). Our patient had low serum leptin and adiponectin levels and insulin resistance. Pathological studies on biopsied muscle disclosed mild dystrophic change and highly reduced expression of PTRF-CAVIN. It was concluded that our PTRF-CAVIN deficient patient showed not only CGL but also asymptomatic elevation of serum CK because of her mild muscle dystrophic change.

Hyper-CK-emia in pediatric celiac disease: prevalence and clinical importance

Hyper-transaminasemia (HT) is a well-known laboratory sign of celiac disease (CD); however, hyper-creatine phosphokinase (CK)-emia (HCK) is not so familiar. As there are reported cases of myopathy associated CD in the literature, we aimed to investigate serum CK levels of children with CD. Newly diagnosed 126 children were included. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and CK levels were determined. Mean age was 8.7+/-4.4 years (11 mo to 18 y). Of patients, 77 (61.1%) had classic form, 49 (38.9%) had atypical form. Elevated levels of AST, ALT, and CK, respectively, were found in 65 (51.6%), 45 (35.7%), and 50 (39.7%) patients. Isolated HCK was detected in 9 (7.1%) patients. AST, ALT, and CK were all elevated in 29 (23.0%) children. Mean serum AST, ALT, and CK levels were found as 56.1+/-53.7 U/L (11 to 403), 44.7+/-44.0 U/L (7 to 290), and 258.0+/-686.5 U/L (36 to 5956), respectively. In 95 (75.4%) children, AST/ALT value was greater than 1, and in 19 (15.1%) it was greater than 2. We found positive correlations with the level of CK and AST, and ALT (P=0.01). CK level was inversely correlated with hemoglobin and cholesterol levels (P=0.013 and 0.007). In conclusion, this is the first study, which determined elevated serum levels of CK in CD and demonstrated that HCK is as common as HT in children with CD. We emphasize that HT seen in CD is not necessarily a sign of liver injury, but may also be due to myopathy.

CAV3 gene mutation analysis in patients with idiopathic hyper-CK-emia

As caveolin-3 deficiencies may explain persistent hyper-CK-emia, we performed CAV3 gene mutation analysis and immunohistochemistry for caveolin-3 in 31 patients with idiopathic hyper-CK-emia. In 2 of 29 patients who donated blood, variants in the CAV3 gene were detected. Although immunohistochemical analysis strongly suggested that caveolin-3 was properly localized in the muscle tissue of the two affected patients, it may not function normally and could thus explain their persistent hyper-CK-emia. Our findings contribute to the clarification of unexplained persistent hyper-CK-emia, but further research is needed before CAV3 gene mutation analysis becomes part of the routine evaluation of these patients.

Muscle biopsy in the evaluation of patients with modestly elevated creatine kinase levels

The utility of muscle biopsy in patients with modest elevations of serum creatine kinase (CK) level but normal neurological examinations and nondiagnostic electrodiagnostic studies is uncertain. We performed systematic, extensive studies on muscle biopsies of 20 such patients. A definitive diagnosis was arrived at in only 1 by histochemical studies, although 4 others demonstrated minor myopathic changes. Biochemical evaluation led to a diagnosis in an additional 5. Muscle biopsy is useful for evaluating such patients, but extensive studies of the muscle are necessary.

Response to exercise of patients with idiopathic hyper-CK-emia

Patients with an idiopathic increase in serum creatine kinase (CK) levels (hyper-CK-emia) have a benign prognosis, but symptoms may be disabling in daily life. Previous studies have suggested that physical exercise increases the severity of complaints in these patients. We studied whether maximal and submaximal bouts of exercise on a cycle ergometer are harmful for patients with idiopathic hyper-CK-emia. Such dynamic exercise did not lead to larger increases in serum CK activity or more complaints in 11 patients with idiopathic hyper-CK-emia, compared with 11 age-matched healthy controls. Our data suggest that exercise does not result in more extensive muscle damage in patients with idiopathic hyper-CK-emia than in healthy subjects.