Metastatic calcification

Metastatic calcificationis deposition ofcalcium saltsin otherwise normal tissue, because ofelevated serum levels of calcium,which can occur because of deranged metabolism as well as increased absorption or decreased excretion ofcalciumand related minerals, as seen inhyperparathyroidism.

In contrast,dystrophic calcificationis caused by abnormalities or degeneration of tissuesresulting in mineral deposition, though blood levels of calcium remain normal. These differences in pathology also mean that metastatic calcification is often found in many tissues throughout a person or animal, whereas dystrophic calcification is localized.

Density-Dependent Colour Scanning Electron Micrograph SEM (DDC-SEM) of cardiovascular calcification, showing in orange calcium phosphate spherical particles (denser material) and, in green, the extracellular matrix (less dense material).

Metastatic calcification can occur widely throughout the body but principally affects theinterstitial tissuesof the vasculature, kidneys, lungs, and gastric mucosa. For the latter three, acid secretions or rapid changes in pH levels contribute to the formation of salts.

Causes

Hypercalcemia, elevated blood calcium, has numerous causes, including

1. Elevated levels ofparathyroid hormonedue tohyperparathyroidism,leading tobone resorptionand subsequent hypercalcemia by reducing phosphate concentration.
2. Secretion ofparathyroid hormone-related proteinby certain tumors.
3. Resorption of bone due to
   • Primary bone marrow tumors (e.g.multiple myelomaandleukemia)
   • Metastasis of other tumors, breast cancer for example, to bone.
   • Paget disease
   • Immobilization
4. Vitamin Drelated disorders
   1. Vitamin D intoxication
   2. Williams syndrome(increased sensitivity to vitamin D)
   3. Sarcoidosis
5. Kidney failure