Isaacs syndrome is a disorder of unknown etiology characterized by muscular cramps and myokymia. It was described by Isaacs in 1961 and termed by him "continuous muscular activity syndrome". A 14-year-old male child was admitted to our clinic because of muscular cramps, myokymia, excessive sweating, and headache of one-month duration. Electromyographic recordings showed typical findings for Isaacs’ syndrome. Renal biopsy was performed because of hypertension and excessive proteinuria. Mesangial proliferative glomerulonephritis was revealed on the biopsy. After carbamazepine and steroid were administered, his findings and proteinuria completely resolved. He is the first case according to our information having Isaacs’ syndrome together with mesangialproliferative glomerulonephritis.

Keywords: Isaacs sendromu, mezangioproliferatif glomerülonefrit, Isaacs’ syndrome, mesangial proliferative glomerulonephritis, children