Serum ionized versus total magnesium in progressive renal failure -: a cross-sectional study

(O) under bar(b) under bar(j) under bar(e) under bar(c) under bar(t) under bar(i) under bar(v) under bar(e) under bar: The aim of this Study was to investigate serum Ionized magnesium (i-Mg) levels in patients with various stages of renal failure and to compare them with serum total magnesium (t-Mg). (M) under bar(e) under bar(t) under bar(h) under bar(o) under bar(d) under bar(s) under bar (a) under bar(n) under bar(d) under bar (m) under bar(e) under bar(t) under bar(h) under bar(o) under bar(d) under bar(s) under bar: We Studied 69 nondiabetic ambulatory patients not receiving diuretics, polystyrene sulfonate or NaHCO3. Serum i-Mg was measured with an ion-selective electrode and serum t-Mg by ion chromatography. Renal function was determined by the creatinine clearance (C-Cr), applying the normalized Cockcroft-Gault formula. (R) under bar(e) under bar(s) under bar(u) under bar(l) under bar(t) under bar(s) under bar: Overall, i-Mg, as well as t-Mg, showed a statistically significant negative logarithmic correlation with C-Cr (i-Mg: r = -0.75; t-Mg: r = -0.73) and i-Mg highly correlated with t-Mg (r = 0.94). Surprisingly, in mild renal failure (C-Cr > 80 ml/min/1.73 m(2)), i-Mg and t-Mg were in the low-normal to hypomagnesemic range (i-Mg <= 0.56 mmol/l, t-Mg: 0.85 mmol/l). In moderate renal failure (C-Cr < 30 and <= 80 ml/min/1.73 m(2)), I-Mg and t-Mg were usually in the reference interval (i-Mg: 0.49 - 0.63 mmol/l, t-Mg: 0.75 - 0.95 mmol/l). In severe renal failure (C-Cr < 30 ml/min/1.73 m(2)), i-Mg and t-Mg were in the high-normal to hypermagnesemic range (i-Mg >= 0.56 mmol/l, t-Mg >= 0.85 mmol/l). (C) under bar(o) under bar(n) under bar(c) under bar(l) under bar(u) under bar(s) under bar(i) under bar(o) under bar(n) under bar(s ) under bar: The measurement of i-Mg offered no advantage over the measurement of t-Mg. The observation of low Mg values in mild renal failure may have implications for the common treatment of chronic renal failure (CRF) patients with drugs that have a Mg-lowering side effect (diuretics, potassium-lowering agents).