Severe hypokalemic paralysis as a manifestation of a mitochondrial disorder

Mitochondrial disorder (MtD) is usually a multisystem disease due to impaired mitochondrial energy production. Severe hypokalemia resulting in muscle weakness and rhabdomyolysis has not been reported as a phenotypic feature of MtD. Here we describe a 60-year-old male patient who developed myalgias followed by generalized muscle weakness a few days before admission. Symptoms were attributed to severe hypokalemia that occurred after the patient had discontinued spironolactone, a competitive antagonist of the aldosterone receptor, four months earlier on his own judgment. Spironolactone was given for 10 years to treat suspected primary hyperaldosteronism (Conn's syndrome). He presented with myopathic face, bilateral ptosis, hypertelorism, brachydactylia, weakness of the axial and limb muscles, and bilateral leg edema. Hypertelorism and brachydactylia are known as physical traits of MtD. Laboratory investigations revealed hypokalemia of 1.7 mmol/l and elevated serum levels of creatine kinase (2,772 U/l). Electrocardiogram showed sinus rhythm, left bundle-branch-block, repolarization abnormalities, and prolonged QTc (571 ms), which is associated with a propensity to ventricular arrhythmias. Diagnostic work-up revealed bilateral adenomas of the suprarenal glands. Conn's syndrome was regarded as a manifestation of MtD, since MtDs are frequently associated with endocrine abnormalities. The patient also presented with occasional double vision, ptosis, renal insufficiency, bilateral renal cysts, hypertriglyceridemia, arterial hypertension, and hypertrophic cardiomyopathy. Taken together, we have made the diagnosis of MtD. In conclusion, MtD may be associated with adrenal adenomas, which may cause severe symptomatic hypokalemia, manifesting as generalized weakness and myalgias due to rhabdomyolysis. Endocrine involvement may be a phenotypic feature of MtD.