Endocrine Abstracts

PHP has four serious complications: urinary calcium stone disease; nephrocalcinosis; high-turnover metabolic bone disease; and hypercalcemia. Medical management is reserved for patients who are asymptomatic or who have failed, refused or are unfit for surgery. Aims of medical management are to prevent increase in severity of disease and to ameliorate and prevent the disease complications.

Prevention of increase in severity includes regular follow-up, ensuring calcium and vitamin D sufficiency, avoiding drugs stimulating the parathyroids, and maintaining normal renal function.

Stones that compromise renal function are removed surgically or by lithotripsy. Stone recurrence is prevented by reducing urine pH, oxalate, and calcium, and by increasing urine volume to decrease the saturation of calcium salts in the urine.

Nephrocalcinosis occurs in the severe forms of the disease and is usually accompanied by impaired renal function. Pathogenesis is obscure and management remains unsatisfactory.

High-turnover metabolic bone disease has two main presentations. In the severest form there are subperiosteal erosions, brown cysts, and skeletal fractures. In the milder form there are fractures and osteoporosis mainly affecting cortical bone. Antiresorptive agents including estrogens, SERMs and bisphosphonates reduce bone resorption and increase BMD. However, they reduce serum calcium and have the potential to increase parathyroid activity.

Hypercalcemia when severe is symptomatic. Its management has become much easier with the development of oral calcimimetics. These drugs move the calcium-PTH setpoint to the left and maintain serum calcium in the normal range. They reduce serum PTH over a 24 hr dosing regimen but do not produce a ‘medical parathyroidectomy’.

Good medical management of PHP remains a challenge. However, with our better understanding of aetiology and pathogenesis of PHP and its complications, and the introduction of antiresorptives and calcimimetics, medical management is becoming more specific and more proactive.