A 46-year-old woman presented with progressive weakness and intense myalgia for a week that prevented her from walking.
She had a history of hypothyroidism treated with T4 50 mcg/day and intestinal bypass due to morbid obesity 5 years earlier, with weight loss of more than 70 Kg since then.
She had 4 to 5 daily pasty stools since surgery.
On admission he was alert, eupneic and apyretic.
He had weight loss with a body mass index (BMI) of 19.
She was well hydrated and her blood pressure (BP) was 120/70 mmHg.
Neuromuscular evaluation showed generalized hypotonia, paresis of four limbs without fasciculations and osteotendinous reflexes present.
He had a plasma potassium (K+pl) of 1.1 mEq/L and elevated CK.
TSH levels were within the normal range.
Hydroelectrolytic replacement was started with improvement of muscle paresis, progressive decrease of myalgias and normalization of K+pl and CK values.
Hypokalemia was attributed to losses of digestive origin secondary to the surgical procedure.
Although its severity may be the cause of neuromuscular manifestations, the finding of elevated CK levels confirmed the suspicion of associated MR.
