Kidney Stones as a Manifestation of Hypercalcemic Disorders

The serum calcium level should be measured in all patients with stones. Although the vast majority has a normal value, those who have elevated serum calcium levels must be identified not only to prevent further urolithiasis but also because of the implications for other organ systems. In a patient with kidney stones, an elevated serum calcium level usually means hyperparathyroidism or, much less frequently, sarcoidosis. The milk-alkali syndrome as a cause of hypercalcemia and urinary calculi is unusual since the advent of H2 acid-blocking drugs, although one recent report 7 suggested that increased use of calcium carbonate supplements may be generating a new form of this syndrome. If kidney stones and serum calcium abnormalities occur in an unexpected situation, such as in an anorectic 15-year-old girl, overuse of the fat-soluble vitamins should be suspected. Hypercalcemia associated with malignancy does not result in stone formation ordinarily. These patients probably do not live long enough to form stones, and the renal damage that occurs reduces the excretion of other lithogenic substances. Familial hypocalciuric hypercalcemia (discussed further subsequently) also is not usually characterized by urolithiasis.