An unusual case of leg weakness in a patient with diabetes and Addison's disease (Is there a common link?)
Julia Platts, Maitrayee Choudhury, Alexis Manning & Nicholas Withenshaw
Both diabetes and Addisons are conditions which can be associated with muscle weakness and altered potassium levels. This is a case of recurrent muscle paralysis in a patient with both conditions with the underlying abnormality being the neurological condition of hypokalaemic periodic paralysis.
A 23-year-old Caucasian gentleman was admitted to medical admissions with sudden onset weakness of his lower legs. On examination he had reduced power of his hips and knees, with intact sensation. The main finding from his blood tests was a serum potassium level of 3.2 mmol/l. He had a past medical history of poorly controlled type 1 diabetes and Addisons disease. His weakness improved following a short course of oral potassium replacement. He was discharged home but readmitted 2 days later with similar symptoms and potassium of 2.9 with. Autoimmune markers, thyroid function tests and plasma renin levels were normal. He underwent an EMG study, which revealed abnormalities showing reduced myotonic discharges, which supported a diagnosis of hypokalaemic periodic paralysis.
This is an autosomal dominant condition characterised by intermittent episodes of flaccid paralysis with associated hypokalaemia, which are reversible. The genetic defect leads to an alteration in voltage gated sodium and calcium channels in the skeletal muscle. Rare associations have been made with diabetes and hypokalaemic periodic paralysis, which has been triggered by insulin administration. Hypokalaemia may also be precipitated by excessive corticosteroid or excessive mineralocorticoid replacement. This case raises some interesting and challenging questions regarding the complex management of the condition in view of the electrolyte abnormalities in the background of his medical conditions and whether there may a genetic link underlying all three diseases.