A Case of Magnesium Deficiency Associated with Insufficient Parathyroid Hormone Action and Severe Osteoporosis

Abstract

Abstract. The relationship between osteoporosis and magnesium (Mg) deficiency is still controversial. Here we report a case of an 82-year-old woman with a giant adenomatous goiter and severe osteoporosis with multiple vertebral fractures, whose clinical course indicated that her osteoporosis was probably due to Mg deficiency. She visited our hospital for treatments of tetany. Laboratory data showed the existence of hypomagnesemia, hypocalcemia, hypokalemia, vitamin D deficiency, and slightly elevated intact PTH. Intravenous administration of Mg not only improved these electrolyte abnormalities but also increased serum levels of intact PTH, bone formation markers, 1,25-dihydroxyvitamin D, as well as bone resorption markers in the urine, and lowered urinary phosphate reabsorption. Hypomagnesemia on admission seemed to arise from long-lasting poor food intake and malnutrition, because it improved after the disappearance of dysphagia with a goiter resection. After the operation, BMD values at the lumbar spine and femoral neck obviously increased during 6 months of Mg supplementation without any specific therapies for osteoporosis. Mg deficiency in this case seemed to cause impaired secretion of PTH from the parathyroid and the refractoriness of bone and kidney to the hormone, which led to the suppression of both bone remodeling and renal vitamin D production. These processes were probably linked to her severe osteoporosis, which was reversed by Mg supplementation. SERUM calcium levels are normally regulated within a relatively narrow range by the parathyroid gland through a negative feedback mechanism: Increased secretion of parathyroid hormone (PTH) by a fall in blood calcium levels enhances the mobilization of calcium, mainly by bone resorption, and then calcium levels are rapidly restored. Chronic magnesium (Mg) deficiency would result in hypocalcemia [1, 2], because of the impairment of PTH secretion [3][4][5][6][7] and/ or resistance of target organ to PTH action [4,6,8].Previous studies have demonstrated that serum PTH concentration was suppressed in patients with hypomagnesemia [4,5], and Mg substitution therapy enhanced PTH secretion and reversed PTH target-organ resistance, and thus serum calcium concentration returned to normal within several days [4,7]. In addition, Mg deficiency could inhibit the synthesis of 1,25-dihydroxy vitamin D (1,25(OH) 2 D) [9][10][11] as well as its action on bone [11]. Accumulating data have shown that a long-term Mg deficiency and resulting hypomagnesemia could cause osteoporosis and bone fractures through these dysfunctions of PTH and vitamin D action [12,[13][14][15][16][17][18][19]. However, other studies have shown no relationship between Mg deficiency and osteoporosis [20][21][22], and it still seems to be controversial whether or not Mg deficiency could cause osteoporosis. Here we report a patient with a giant adenomatous goiter and severe osteoporosis exhibiting hypomagnesemic hypocalcemia, whose osteoporosis was reversed by Mg supplementation with chronological improv...

The association of bone mineral density and parathyroid hormone with serum magnesium in adult patients with sickle-cell anaemia

“…These data suggest that a blunted PTH response in hypo-Mg patients may be the causative factor for BMD reduction in SCD. These results are supported by previous studies which suggested that Mg deficiency causes impairment of PTH release from the parathyroid and the refractoriness of bone and kidney to the hormone, which may lead to the suppression of bone remodelling [14, 25, 31, 32]. …”

“…Additionally, Mg regulates biological processes important in bone remodelling such as calcium absorption, parathyroid hormone (PTH) secretion, osteoblast adhesion and bone formation [11–13]. The Mg deficiency produces hormonal and skeletal disturbances that have been associated with a number of bone disorders including osteoporosis [14, 15]. This has been supported by experimental magnesium deficiency studies showing that insufficient dietary Mg intake increased osteoclast number, and bone loss in laboratory animals [16].…”

Hypomagnesemia and Inflammation: Clinical and Basic Aspects

“…Osteoporotic postmenopausal women with a positive magnesium-loading test for magnesium deficiency were vitamin D deficient and had low serum parathyroid hormone levels (112,117). In another study, osteoporosis was reversed by oral magnesium treatment, with subsequent improvement in bone mineral density (50).…”

“…Patients with hypomagnesemia are at risk for bone fractures along with osteoporosis (50,109). Hypomagnesemia is often associated with other diseases that occur in elderly patients where a reduction in bone mass is associated with a reduction of magnesium content (7,118).…”

Trace elements and bone health

“…Magnesium deficiencies lead to reduced levels of 1,25(OH) 2 D 3 vitamin in serum, slightly elevated intact parathormone and increased osteoclast activity. The number of osteoblasts decreases [ 27 ]. Malfunction of bone mineralization is similar to osteomalacia.…”