The practicing physician can consider a simplified scheme when confronted with a patient with a disorder of calcium and skeletal metabolism – the serum or urinary calcium can be abnormally high or low and bone density can be increased or decreased.

In practical terms, when the serum calcium is high, primary hyperparathyroidism and malignancy are at the top of her diagnostic list; when it is low, renal disease and hyoparathyroidism pertain. When the urinary calcium is high, one of the hypercalciuric diseases should be considered, resorptive, absorptive, or tubular defective hypercalciuria; when low, familial hypocalciuric hypercalcemia.

When bone density is decreased, it is usually due to osteoporosis or osteomalacia; when increased, osteopetrosis should be considered. These diagnostic categories can be properly assigned when on considers the interaction among the calcium regulating hormones that have been describe in this chapter and orders the appropriate diagnostic tests. In most case, the correct diagnosis is readily and satisfyingly made.