Phosphorus and Magnesium

Publisher Summary This chapter discusses the various disorders of phosphorous and magnesium. Phosphate is the most abundant constituent of all tissues. Disturbances in phosphate homeostasis can affect any organ. Phosphate deficiency can result in: osteomalacia, rickets, red cell dysfunction, rhabdomyolysis, metabolic acidosis, and cardiomyopathy. Phosphate excess can cause: soft tissue calcification, hypocalcemia, tetany, and secondary hyperparathyroidism. The regulation and disorders of phosphate homeostasis and magnesium homeostasis are described in this chapter. The most common abnormality of phosphate homeostasis is aberrant renal reabsorption of phosphate, which may lead to hypophosphatemia or hyperphosphatemia. Magnesium is the most abundant intracellular divalent cation and it plays an important role in the regulation of enzyme activities and neuromuscular excitability. Kidney plays an important regulatory role in maintaining the serum magnesium concentration. Certain factors are associated with increased and decreased excretion of magnesium. The disorders of magnesium homeostasis are not uncommon with hypomagnesemia, and hypermagnesemia. Treatment of magnesium intoxication should reflect that this abnormality generally occurs in patients on magnesium replacement.