Correction of Low Circulating Levels of 1,25‐dihydroxyvitamin D by 25‐hydroxyvitamin D During Reversal of Hypomagnesaemia

Abstract

The effect of 25-hydroxyvitamin D (25OHD), given orally during the reversal of hypomagnesaemia, was studied in five patients with hypomagnesaemic hypocalcaemia and low serum levels of 25OHD and 1,25-dihydroxyvitamin D (1,25(OH)2D). The results were compared to those obtained in five other patients with similar initial levels of magnesium, calcium, 25OHD and 1,25(OH)2D who did not receive 25OHD. Serum levels of 1,25(OH)2D in the ten hypomagnesaemic patients were lower than in ten control subjects with low serum levels of 25OHD. The reversal of hypomagnesaemia was similar in the two groups of patients and elicited a similar increase of circulating iPTH levels. The expected increase of circulating 25OHD was observed in patients supplemented with 25OHD; their circulating 1,25(OH)2D rose within 48 h to normal levels, contrasting with the delayed and poor increase of 1,25(OH)2D in patients receiving no 25OHD. The evolution of serum calcium was however identical in the two groups. Our results suggest that vitamin D deficiency was a significant factor leading to low circulating levels of 1,25(OH)2D in hypomagnesaemic hypocalcaemic patients. The biological consequences of low serum 1,25(OH)2D in these patients remain unclear, but clearly, normal levels of 1,25(OH)2D are not essential for the correction of hypomagnesaemic hypocalcaemia.

Magnesium, vitamin D status and mortality: results from US National Health and Nutrition Examination Survey (NHANES) 2001 to 2006 and NHANES III

“…In a subsequent study of five magnesium-deficient patients, intramuscular treatment with magnesium alone also did not significantly increase 25(OH)D, but magnesium infusion together with pharmacological dose of 25(OH)D substantially increased both 25(OH)D and 1,25(OH) 2 D among patients with magnesium deficiency. One interpretation is that magnesium treatment does not affect 25(OH)D status [23,27]. However, we postulate that several factors may have contributed to the insignificant increase in 25(OH)D status.…”

“…Interestingly, a study conducted among osteoporosis patients showed much higher prevalence rates of magnesium deficiency or insufficiency among people with insufficient 25(OH)D than those with sufficient 25(OH)D [26]. Two small clinical trials of magnesium-deficient patients [23,27] found that magnesium infusion alone led to a non-significant increase in 1,25(OH) 2 D and 25(OH)D [23] whereas magnesium infusion plus oral vitamin D substantially increased both serum 25(OH)D and 1,25(OH) 2 D [27]. These findings suggest a potential interaction between vitamin D and magnesium treatments and a possible moderate effect of magnesium on 25(OH)D status.…”

The Hypocalcemic Disorders

“…Hypomagnesemia can be seen in the settings of chronic gastrointestinal disease or nutritional deficiency especially in alcoholics. To further complicate matters, vitamin D deficiency is often present in hypomagnesemic patients [82]. Resistance to the action of PTH at the level of bone and kidney may also contribute to the hypocalcemia seen in the setting of magnesium deficiency.…”

Magnesium Depletion and Parathyroid Function

“…With the exception of studies of normal individuals with experimentallyinduced Mg deficiency, much of the evidence linking Mg deficiency to abnormalities of vitamin D metabolism appears largely anecdotal. The one clearly established link between Mg depletion and vitamin D metabolism is that most of the hypocalcemic Mg-deficient patients have low serum concentrations of 1,25-dihydroxyvitamin D. [46][47][48][49] Saggese et al 50 reported Mg-deficient diabetic children put on a low calcium diet demonstrated a subnormal rise in both serum PTH and 1,25-dihyroxyvitamin D concentrations, suggesting that Mg deficiency may impair this pathway's normal functioning. As we have seen, Mg deficiency is associated with low serum intact PTH concentration, and inasmuch as PTH is a trophic factor in the generation of 1,25-dihydroxyvitamin D, low PTH levels may in themselves constitute the chief explanation for low serum concentrations of 1,25-dihydroxyvitamin D in Mg deficiency.…”