Primary Hyperparathyroidism: A Tale of Two Cities Revisited - New York and Shanghai

In the 1970s, with the advent of biochemical multichannel screening in the United States and other western countries, the clinical presentation of primary hyperparathyroidism (PHPT) changed from a symptomatic to an asymptomatic disorder. However, in Asian countries, like China, PHPT did not show this evolution, but rather continued to be a symptomatic disease with target organ involvement. In this paper, we revisit the clinical features of PHPT in New York and Shanghai, representative United States and Chinese cites, over the past decade. The questions we address are whether the disease evolved in China to a more asymptomatic one and, whether in the United States further changes are evident. The results indicate that while PHPT continues to present primarily as an asymptomatic disease in the United States, a new phenotype characterized by normal serum calcium and high parathyroid hormone levels, normocalcemic PHPT, has emerged. Data from Shanghai demonstrates a trend for PHPT to present more commonly as an asymptomatic disorder in China. However, most patients with PHPT in China still manifest classical symptoms, i.e. nephrolithiasis and fractures. A comparison of the two cohorts shows that Chinese patients with PHPT are younger, with higher serum calcium and PTH levels, and lower 25-hydroxyvitamin D levels than patients in New York. Normocalcemic PHPT has not yet been recognized in Shanghai. In summary, although the phenotypes of PHPT in both cities are evolving towards less evident disease, sharp clinical and biochemical differences are still apparent in PHPT as expressed in China and the United States.