ALTERATIONS OF CALCIUM-METABOLISM AND OF PARATHYROID FUNCTION IN PRIMARY ALDOSTERONISM, AND THEIR REVERSAL BY SPIRONOLACTONE OR BY SURGICALREMOVAL OF ALDOSTERONE-PRODUCING ADENOMAS

In order to investigate the possible existence of abnormal calcium met abolism and parathyroid function in primary aldosteronism (PA), we hav e compared the calcium/parathyroid hormone (PTH) profile of patients w ith PA with the profile of healthy normotensive subjects and of patien ts with essential hypertension (EH). Furthermore, we have evaluated th e effects of spironolactone and the surgical removal of aldosterone-pr oducing adenomas on the calcium/PTH profile in the PA patients. Four g roups of 10 subjects each participated in the study: 1) hypertensive p atients with PA, 2) patients with low-renin EH (LREH), 3) patients wit h normal-renin EH (NREH), 4) normotensive healthy subjects (NS). The f our groups were well-matched for age, sex, body mass index, and renal function. The three hypertensive groups were also matched closely for blood pressure values and for duration of hypertension. In all subject s, after 1 week of a controlled intake of Na and K, the following para meters were measured: urine excretion of Na, K, Ca, Mg, and P, plasma levels of K, Mg, inorganic P, total calcium and ionized calcium, and p lasma renin activity, aldosterone concentration, and intact PTH. Blood pressure and laboratory parameters were determined again in all the P A patients after 1 month of 100 mg daily spironolactone administration , and in four out of the 10 PA patients 2 months after surgical remova l of aldosterone-producing adenomas. All of these subjects had undergo ne the same controlled intake of Na and K indicated above. Serum intac t PTH was higher in PA patients than in the other three groups (P < .0 1), and serum ionized calcium was significantly higher in normotensive subjects than in the three hypertensive groups (v PA P < .01, v LREH and v NREH P < .05). An increase in serum ionized calcium and a decrea se in PTH level were associated with both spironolactone administratio n (P < .001) and surgical treatment (P < .05). These results suggest t he presence of calcium metabolism alterations in both PA and EH patien ts, but that these alterations are more exaggerated in PA, so that hig her PTH levels are needed for maintaining low-normal levels of serum i onized calcium.