Rhabdomyolysis and Cardiomyopathy in a 20-Year-Old Patient with CPT II Deficiency

Rhabdomyolysis Associated with Recent SARS-COV-2 Infection in a Patient with Carnitine Palmitoyltransferase II Deficiency

Carnitine palmitoyltransferase II deficiency (CPT II) is an autosomal recessive inherited disorder of long-chain fatty acid oxidation in the mitochondrial matrix, resulting in an inability to utilize fat for energy in cells. The most frequent myopathic form occurs in young adults and is associated with recurrent episodes of exercise-induced rhabdomyolysis. The myopathic form is caused by the Ser113Leu mutation of the CPT II gene. Rarely, massive rhabdomyolysis could be complicated by acute kidney injury (AKI), cardiomyopathy, and respiratory insufficiency. We present a case of an 18-year old male with myalgia, muscular weakness, and dark-colored urine after prolonged exercise and a recent mildSARS-CoV-2infection. Massive rhabdomyolysis was diagnosed with markedly increased serum concentrations of myoglobin and creatine kinase, with normal kidney function. The patient experienced two similar episodes in the years 2017 and 2018, with rhabdomyolysis and AKI treated with hemodialysis. After excluding autoimmune and infectious diseases as causes of recurrent rhabdomyolysis, the patient was genetically tested and Ser113Leu mutation of the CPT II gene was confirmed. When a patient presents with myalgia and dark-colored urine triggered by minor physical activities, genetic testing for possible CPT II deficiency should be initiated. TheSARS-CoV-2infection could be a factor that triggers the occurrence of rhabdomyolysis and aggravates the severity of the attack in patients with CPT II deficiency.

Clinical manifestations and management of fatty acid oxidation disorders

Fatty acid oxidation disorders (FAOD) are a group of rare, autosomal recessive, metabolic disorders caused by variants of the genes for the enzymes and proteins involved in the transport and metabolism of fatty acids in the mitochondria. Those affected by FAOD are unable to convert fatty acids into tricarboxylic acid cycle intermediates such as acetyl-coenzyme A, resulting in decreased adenosine triphosphate and glucose for use as energy in a variety of high-energy-requiring organ systems. Signs and symptoms may manifest in infants but often also appear in adolescents or adults during times of increased metabolic demand, such as fasting, physiologic stress, and prolonged exercise. Patients with FAOD present with a highly heterogeneous clinical spectrum. The most common clinical presentations include hypoketotic hypoglycemia, liver dysfunction, cardiomyopathy, rhabdomyolysis, and skeletal myopathy, as well as peripheral neuropathy and retinopathy in some subtypes. Despite efforts to detect FAOD through newborn screening and manage patients early, symptom onset can be sudden and serious, even resulting in death. Therefore, it is critical to identify quickly and accurately the key signs and symptoms of patients with FAOD to manage metabolic decompensations and prevent serious comorbidities.

Carnitine Palmitoyltransferase II Deficiency (CPT II) Followed By Rhabdomyolysis and Acute Kidney Injury

BACKGROUND:

Carnitine palmitoyltransferase II deficiency (CPT II) is an autosomal recessive disorder and the most common inherited disorder of mitochondrial long-chain fatty acid oxidation, characterised by attacks of myalgia and myoglobinuria. The most common “classic” myopathic form occurs in young adults and is characterised by recurrent episodes of rhabdomyolysis triggered by prolonged exercise, fasting or febrile illness.

CASE PRESENTATION:

We present a case of a 22-year-old Caucasian male admitted to our hospital with fever, dyspnea, fatigue, myalgia and dark urine (brown-coloured). The symptoms appeared after viral infection followed by fever. Acute kidney injury (AKI) developed as a complication, and there was a need for treatment with hemodialysis. At the clinical presentation, the patient had plasma creatine kinase (pCK) level of 130.383 U/L and plasma myoglobin level over 5000 µg/L. Genetic testing (molecular analysis) confirmed the diagnosis of inherited rhabdomyolysis, a metabolic disorder of carnitine palmitoyltransferase II deficiency. A previous episode with the same symptoms, the patient had four years ago but did not ask for medical treatment. The patient was discontinued from hemodialysis because of the resolution of acute kidney injury. The patient was discharged from the hospital in good condition, with a recommendation about his future lifestyle in order to prevent similar episodes.

CONCLUSION:

Every patient presenting with myalgia, dark urine (brown-coloured), high level of pCK and development of AKI requiring hemodialysis, should be explored for inherited rhabdomyolysis induced by CPT II deficiency.

Exertional rhabdomyolysis leading to acute kidney injury: when genetic defects are diagnosed in adult life

Rhabdomyolysis is a common cause of acute kidney injury (AKI) that is usually triggered by trauma. However, less common causes of rhabdomyolysis may precipitate AKI as well, possibly representing a diagnostic challenge even for the experienced nephrologist. Genetic defects of muscle metabolism represent one of these causes and can be overlooked in adults, since these diseases usually become apparent in childhood. We present here a case in which an adult patient with severe exertional rhabdomyolysis leading to AKI was finally diagnosed with a genetic defect of lipid metabolism. A 41-year-old patient was brought to our attention because of AKI and pigmenturia after strenuous physical effort. At admission, the patient was over-hydrated with a weight increase of 3 kg in few days. Laboratory examination showed creatinine of 8.7 mg/dl, along with increased myoglobin and CPK. Urinalysis was positive for haemoglobin and proteins, while urinary sediment analysis did not demonstrate any red blood cell but rather "muddy-brown" casts and tubular cells. Urine output was forced and the patient completely recovered renal function. Genetic analysis later demonstrated the presence of a common mutation of Carnitine Palmitoyl-Transferase II (CPTII). When facing rhabdomyolysis of obscure origin, nephrologists must keep in mind the possibility that even adult patients may have a genetic defect of energy metabolism. In these cases, patients usually experience rhabdomyolysis during exertion, fasting, or infection. CPTII deficiency often has a subtle presentation and might be unrecognized until AKI develops. Therefore, it is important to consider a genetic defect of muscle metabolism even in adult patients when a history of rhabdomyolysis of unclear origin is present.