New findings show that a lower than normal salt level in blood (hyponatremia) at the start of hemodialysis is associated with an elevated risk of mineral bone abnormalities and death. According to findings published in the American Journal of Kidney Disease, 6,127 dialysis patients including 775 who had low salt levels in blood, and 5,278 with normal sodium levels; researchers found that hyponatremia is associated with the following:
- Increased risk of elevated calcium level in the blood (hypercalcemia)
- Increased 29% risk of hypoparathyroidism (decreased function of the parathyroid glands)
- Increased 33% risk of elevated alkaline phosphatase (an enzyme found in all body tissues)
- Increased 42% risk of death.
Although the exact sequence of events describing hyponatremia leading to mineral bone abnormalities is unknown the associations between lower than normal salt level in blood and these mineral abnormalities are derived from the direct actions of hyponatremia on the bone. The investigators explained that hyponatremia may directly increase calcium levels, and suppress parathyroid hormone.
The researchers further noted that the associations between hyponatremia and markers of bone turnover raised the possibility that hyponatremia may contribute to osteoporosis in the dialysis population.