Distribution of the solitary adenoma over the parathyroid glands.

One hundred and ten patients with primary hyperparathyroidism were studied, in which a normal parathyroid gland was found on the same side as an adenoma (both confirmed by histological examination), and the upper or lower location could clearly be defined during surgery. The distribution of the adenomas over the upper and lower glands was unequal: 61.8 per cent in the superior versus 38.2 per cent in the inferior position. Statistical analysis revealed that this is not a random distribution (p = 0.013). The explanation of this relative predilection is unknown. The finding should not influence the surgical procedure for primary hyperparathyroidism.