Answer to case 3 Thyroid function tests were sent, and revealed that the patient was significantly hypothyroid. The patient was diagnosed with hypokalemic periodic paralysis, in this case associated with hypothyroidism. The hypokalemic form is autosomal dominant in two-thirds of cases, affects males more often than females, and its onset is usually before age 25. Frequency of attacks varies from daily to yearly. During an attack, patients are weak proximally more than distally, and limb muscles are more commonly affected than bulbar muscles.
Reflexes are hypoactive.
Attacks may be associated with cardiac dysrhythmias. Diagnosis may be accomplished by provoking an attack with insulin and glucose in a controlled setting. Muscle biopsy reveals centrally placed vacuoles. EMG testing is normal. Mild episodes may be self-limited.