Pseudohypohyperparathyroidism: a case study of differential resistance to parathyroid hormone

To present a rare case of a combination of hyperparathyroidism and hypoparathyroidism in a 30-year-old woman.

We review the laboratory, radiographic, and pathologic findings in a healthy-appearing woman who sustained a patellar fracture after a simple fall at home.

Our patient had features of hypoparathyroidism--that is, tetanic crises and hypocalcemia--and also hyperparathyroidism--fracture of the patella, multiple bone cysts, and confirmed osteitis fibrosa cystica on bone biopsy specimens. These features were associated with a high serum level of intact parathyroid hormone (PTH) and parathyroid hyperplasia. A lack of response of nephrogenic cyclic adenosine monophosphate (cAMP) to PTH stimulation was observed along with subnormal serum cAMP responses. In contrast, urine phosphate excretion increased after administration of PTH.

These results demonstrate a state of renal PTH resistance in a patient with osteitis fibrosa cystica.