Evaluation of secondary hyperparathyroidism in the patients undergoing hemodialysis--focused on parathyroid hormone assay system

We evaluated the degree of secondary hyperparathyroidism (SHPT) in the patients undergoing long-term hemodialysis treatment. Most patients showed improvement of SHPT by administration of the active vitamin D3 analogue. However, some patients developed overt SHPT even under intensive treatment. Pulse therapy with large dose of vitamin D3 for those who suffered from overt SHPT was an effective treatment modality at the initial stage, however, hypercalcemia which developed in the majority of the patients at the later stage of this treatment became an obstacle for the continuation of this treatment. Therefore, early detection of the hypersecretion state of parathyroid hormone (PTH) as well as earlier initiation of intensive therapy are important factors in preventing overt SHPT. Establishment of a suitable assay system for early detection of SHPT is an important task and the high sensitivity-PTH assay system may be the most desirable. Though diabetic patients were not likely to develop overt SHPT, this system could detect even the mild chronological increase of serum PTH level in diabetic patients. On the other hand, relatively earlier initiation of vitamin D3 therapy to the predialysis patients from the conservative treatment stage caused aggravation of deterioration of renal function. Therefore, we should be prudent to initiate vitamin D3 therapy on predialysis patients suffering from renal failure. Strict management of the patients by vitamin D3 as well as calcium supplement therapy along with evaluation of the serum PTH level is still an important measure to avoid overt SHPT.