Physiological Calcium Phosphate Management in Two Biofluids

Abstract

Deanna Nelson

Management of calcium and phosphate in biofluids is key to maintaining physiological mineral homeostasis (i.e., appropri- ate mineralization of hard tissues and an absence of mineral deposition in soft tissues). This review describes and contrasts the ways vertebrates manage calcium phosphate in two biologi- cal fluids (breast milk and serum) and illustrates the benefits of mineral sequestration by proteins. In milk, phosphoprotein-se- questered calcium magnesium phosphates provide nutritional support, whereas in serum, protein-sequestered calcium phos- phates control transport and delivery of calcium and phosphate to tissues for biological function or excretion. In addition, sub- sets of sequestered phosphates in serum have been identified as culprits underlying ectopic deposition of calcium phosphates and toxicity.

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