MICROANATOMY

Detailed explanation-1: -Hypoparathyroidism, acromegaly, and thyrotoxicosis enhance renal phosphate reabsorption resulting in hyperphosphatemia. Hyperphosphatemia can also be due to genetic causes.

Detailed explanation-2: -Hyperphosphatemia is a serum phosphate concentration > 4.5 mg/dL (> 1.46 mmol/L). Causes include chronic kidney disease, hypoparathyroidism, and metabolic or respiratory acidosis. Clinical features may be due to accompanying hypocalcemia and include tetany. Diagnosis is by serum phosphate measurement.

Detailed explanation-3: -For example, hereditary or acquired hypoparathyroidism, in which circulating levels of PTH are low or absent, results in the development of hyperphosphatemia, most likely due to increased renal reabsorption of phosphate.

Detailed explanation-4: -The hungry bone syndrome occurs after the correction of hyperparathyroidism, where osteopenic bones begin to reabsorb and store phosphate and calcium. This leads to increased bone demand for these ions and hypophosphatemia. Acute respiratory alkalosis induces hypophosphatemia via changes in cellular pH.