Effects of the intravenous administration of magnesium sulfate on corrected serum calcium level and nephrogenous cyclic AMP excretion in normal human subjects

Abstract

The effect of intravenous magnesium sulfate infusion on corrected serum calcium level and parathyroid function assessed by determination of nephrogenous cAMP (NcAMP) excretion were studied in normal human subjects. Significant hypermagnesemia induced by the magnesium sulfate infusion for 120 minutes was accompanied by a gradual and progressive decrease in the corrected serum calcium level. NcAMP excretion fell rapidly, reaching a nadir between 60 and 120 minutes after the infusion began, and after that rose above the baseline excretion. Urinary calcium excretion gradually increased, reaching a peak between 120 and 180 minutes after the infusion began and then gradually decreased. Since magnesium was given as the sulfate, it is not clear whether these changes were attributable to magnesium or sulfate or both. As a control study, we performed intravenous sodium sulfate infusion. The sodium sulfate infusion caused slight hypocalcemia, slight hypercalciuria, and a significant increase in NcAMP excretion. These findings indicate that the hypocalcemia and the hypercalciuria caused by the magnesium sulfate infusion is mainly due to the effect of magnesium, and that the decrease in NcAMP excretion during the infusion is due to the effect of magnesium alone. We conclude that the hypocalcemia caused by the magnesium sulfate infusion is mainly due to the renal calcium loss, and that the inhibition of parathyroid function caused by hypermagnesemia may be only partially involved in the early phase of this hypocalcemia.

Mechanism of Urinary Calcium Regulation by Urinary Magnesium and pH

“…4,5 This effect was attributable to magnesium and not sulfate. 6 Attempts have been made to localize the segment where urinary magnesium could mediate its effect on calcium reabsorption in different animal models. Metabolic experi-…”

“…4,5 This effect was attributable to magnesium and not sulfate. 6 Attempts have been made to localize the segment where urinary magnesium could mediate its effect on calcium reabsorption in different animal models. Metabolic experi-ments confirmed that calciuria can be increased by intravenous magnesium infusion in dogs with normal or reduced kidney function, 7 but stop-flow experiments did not precisely identify the segment involved.…”

Effect of Centrifugation on the Ultrastructure of the Parathyroid Gland of the Magnesium-treated Golden Hamster

“…It is biochemically or ultrastructurally reported that Mg decreases the activity of the PTH (Altenahr and Leonhardt, 1972;Cholst et aL, 1984;Suzuki et aL, 1986;Utsumi et aL, 1997). In the PTG of the 1.2G group the rER had significantly increased cornpared with that of the control group.…”

“…On the other hand, it is well known in the biochemical or morphological study that magnesium (Mg) plays an important role in the regulation of parathyroid hormone secretion as well as calcium (Altenahr and Leonhardt, 1972;Cho1st et al , 1984;Suzuki et aL, 1986;Utsumi et aL, 1997).…”

The Effect of Magnesium on the Fine Structure of the Golden Hamster Parathyroid Gland in Vivo and in Vitro

“…Radde et aL (1968) have shown in the rat that the secondary hypocalcemia following Mg load is due to stimulation of calcitonin secretion by an elevated Mg level , and that the persistence of hypocalcemia in animals bearing functioning parathyroid glands is due to suppression of PTH secretion. Suzuki et al, (1986) have reported in normal human subjects that the hypocalcemia caused by Mg is mainly due to the renal calcium loss, and the suppressive effect of Mg on parathyroid function may be only partially involved in the early phase of the hypocalcemia. The present in vivo study of the hamster demonstrates that the serum calcium level significantly decreased at 30 min and 1 hr after Mg injection, and that the hamster reacts similarly, developing hypocalcemia after Mg injection.…”