Severe hyperparathyroidism in a pre-dialysis chronic kidney disease patient treated with a very low protein diet.

The present report describes a case of a 64-year-old pre-dialysis woman with chronic kidney disease (CKD) stage 5, who developed severe hyperparathyroidism. This patient had been on a very low protein diet (VLPD) to delay the progression of CKD and the need for renal replacement therapy (RRT). Her serum calcium levels were high-normal to slightly high during this time. However, her serum intact parathyroid hormone (PTH) levels increased from 400 to 1160 pg/ml rapidly over a period of 3 months. Serum 1,25-(OH)2D levels were low, and ultrasound of the neck showed three markedly enlarged parathyroid glands exceeding 2 cm. Parathyroidectomy was performed, and all glands showed nodular hyperplasia, which indicated severe secondary hyperparathyroidism leading to tertiary. Severe secondary hyperparathyroidism requiring surgical intervention is usually observed in patients with long-term RRT and is relatively rare in the pre-dialysis patient. In this case, extension of the pre-dialysis period by VLPD may have predisposed this patient to develop severe secondary hyperparathyroidism. Thus, careful monitoring of calcium, phosphorus, and PTH may be necessary in patients treated with VLPD even before renal replacement therapy. Furthermore, initiation of dialysis should not be excessively delayed by strict protein restriction dietary therapy.