Magnesium: 142 controls: 1.8% (range 0.5-4%) 74 hypomagnesemic Extra-Renal origin 1.4% (range 0.5-2.7%) Renal origin 15% (range 4-48%) Authors conclusion: >4% per cent is indicative of inappropriate renal magnesium loss Fractional excretion of magnesium in normal subjects and in patients with hypomagnesemia. Potassium 312 normal subjects: 8% (range 4-16%) 84 hypokalaemic patients Extra-renal origin: 2.8% (range 1.5-6.4%) Renal origin: 15% … Continue reading FERE: Fractional excretion of random electrolytes