A 50-year old female presented with two days of progressively worsening of shortness of breath, cough and muscle cramps in\r\nthe lower limbs. She had the history of frequent fl are up of asthma, 30 pack years of smoking history. Review of systems was\r\nremarkable for dry cough and shortness of breath for two days partially relieved with the rescue inhaler. She denied chest pain,\r\nexcessive sweating, palpitations and passing out. Vitals, blood pressure 110/68, pulse 90 bmp, temp 98.2 F recorded orally, respiratory\r\nrate 24/min with saturation 94%. She had wheeze at both the lung bases. CVS examination was normal. EKG showed normal sinus\r\nrhythm. She used 8 to 10 times a day the rescue inhaler containing Levalbuterol in the past three days. Labs revealed WBC of 11 with\r\n10% eosinophils, CPK was 98 U/L, her serum electrolytes Na 140 mEq/L, K 3.3 mEq/L, Ca 9.2 mEq/L, Cl 100 mEq/L, HCO3 22 mEq/L,\r\nchest X-ray showed non-specifi c fi ndings related to obstructive lung disease. Peak fl ow meter readings were low. Ankle brachial index\r\nscore of 1.2, arterial Doppler lower extremities showed no abnormalities. All the above lab workup revealed no abnormalities except\r\nincreased eosinophil count and low potassium levels. She was not on any drugs which are known to lower serum potassium levels,\r\naft er doing all the work up she was prescribed with starting dose of 40 mg oral prednisone tapered in one week, Tudorza inhaler and\r\nasked her to hold the rescue inhaler and follow-up in 1 week. During her follow-up visit, she told that her symptoms were relieved\r\nand repeated electrolyte labs were normal. Shortness of breath and cough are the common problems encountered by the Internist. But\r\nmuscle cramps in patients taking beta agonist inhaler are usually rare. Even though she has 30 pack years of smoking history, normal\r\nankle brachial index and arterial Doppler ruled out the peripheral artery disease. Normal CPK ruled out infl ammatory causes of her\r\ncomplaint. Th e point is an orderly approach is imperative in determining the less common causes of this problem. One approach is\r\ntaking a detailed history and sorting out the reasons for the problem so that the possibility of missing the rare causative factors can\r\nbe minimized and also the unnecessary diagnostic workup can be prevented. In this patient with known history of asthma presenting\r\nwith worsening shortness of breath and cough clearly indicates as an asthmatic fl are up. But with detailed history it became evident\r\nthat she used rescue inhaler an excessive number of times a day than suggested, giving the clues for her lower limb muscle cramps.\r\nLevalbuterol, a short-acting beta agonist, is the drug present in her rescue inhaler which can rarely lower the serum potassium level\r\ncausing the muscle cramps. Physicians should be profi cient in addressing rare possibilities. Understand the side eff ects of the drugs\r\nof asthma. Although widely studied in the literature, recognize that short-acting beta agonist (SABA) in an inhaled quantity is an\r\nuncommon cause of muscle cramps. SABA causing muscle cramps should be suspected in a patient with decreased serum potassium\r\nlevels with no other known factors for lowering potassium and when rest of the workup is normal. Th is case illustrates that SABA even\r\nin inhaled amounts can cause muscle cramps mostly when taken more than six times a day.
