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Recent reviews recommended the use of the aldosterone/renin ratio (ARR) to screen for primary hyperaldosteronism. However, widely different cutoff levels have been proposed, and test characteristics of ARR under different conditions of sampling are not known. We conducted a retrospective review among 45 subjects with carefully validated diagnoses of primary hyperaldosteronism and 17 subjects with essential hypertension to study the utility of ARR. Sixty-two patients with 75 sets of plasma renin activity (PRA), aldosterone, and ARR values from a postural study and 48 sets of values from a saline suppression test were analyzed. Ninety-four percent of these subjects underwent investigations because of hypokalemic hypertension.ARR yielded larger areas under the curve in the receiver-operating-characteristics curve than PRA or aldosterone under all conditions of testing. Our results confirmed the superiority of ARR to either aldosterone or PRA alone as a diagnostic test for primary hyperaldosteronism.ARR cutoff levels were significantly affected by the condition of testing. Depending on posture and time of day, it varied from 13.1-35.0 ng/dl per ng/ml.h in our study population. When using ARR for screening primary hyperaldosteronism, posture and time of sampling should be standardized both within and between centers to minimize variability in cutoff levels.

Bone mineral density (BMD) has been shown to be increased in postmenopausal females with postthyroidectomy hypoparathyroidism, but it is not known whether similar gains occur in patients with idiopathic hypoparathyroidism. In this study, we measured the BMD of lumbar spine and proximal femur in 14 patients, 8 with idiopathic hypoparathyroidism and 6 with postthyroidectomy hypoparathyroidism, using dual-energy x-ray absorptiometry. Their age ranged from 23-57 yr old, with a mean of 42.5 yr. The results showed that patients with hypoparathyroidism had a higher BMD than the normal age- and sex-matched population. This was particularly evident at the lumbar spine (L2-L4), with positive Z-score of 1.93 +/- 1.03, whereas Z-score at the femoral neck was 1.14 +/- 0.62 SD. Subgroup analysis showed that those with postthyroidectomy hypoparathyroidism had a mean lumbar spine BMD of 1.434 g/cm(2) and femoral neck BMD of 1.026 g/cm(2), compared with a mean BMD of 1.364 g/cm(2) and 1.022 g/cm(2) at spine and hip, respectively, for those with idiopathic hypoparathyroidism. Statistical analysis did not reveal any significant difference in the BMD, T-score, and Z-score of the bone, at these two sites, between the two groups. In conclusion, the state of chronic hypoparathyroidism is associated with increased BMD, especially at the lumbar spine. Those with idiopathic hypoparathyroidism have a similar degree of increase in BMD as those with postthyroidectomy hypoparathyroidism.

Many studies showed an increased occurrence of primary hyperparathyroidism during lithium therapy. We studied 53 patients receiving lithium therapy prospectively for 2 yr. Serum PTH levels were unequivocally elevated. The baseline PTH level was 2.8 +/- 1.2 pmol/L and increased progressively to 3.9 +/- 1.5 pmol/L after 2 yr (P < 0.0005). There was no change in serum calcium, alkaline phosphatase, inorganic phosphate concentrations or tubular reabsorption of phosphate in relation to glomerular filtration rate. Fasting urinary reabsorption of calcium increased significantly (P < 0.0005), which was concordant with the PTH change. Fasting and 24-h urinary excretion of calcium decreased significantly (P < 0.0005), suggesting reduced, rather than enhanced, bone resorption as in primary hyperparathyroidism. This may be the main mechanism in maintaining normocalcemia, despite PTH elevation, during lithium therapy.