Clinical characteristics of the patients with asymptomatic primary hyperparathyroidism

The prevalence of asymptomatic primary hyperparathyroidism (PHPT) in China is lower than that in European and American countries and the study about the characteristics of asymptomatic PHPT was rare in China. This study aims to explore the characteristics of asymptomatic PHPT.

Clinical data of 150 patients with PHPT confirmed by operation and pathological examination were retrospectively analyzed. The patients were assigned into a symptomatic PHPT group (n=124) and an asymptomatic PHPT group (n=26).

The proportion of adenomas was higher than that of adenocarcinoma in the asymptomatic PHPT group. The proportion of the first diagnosis due to hypercalcemia found via biochemical examination in the asymptomatic PHPT group was higher than that in the symptomatic PHPT group (76.92% vs 25.81%, P<0.001). The duration was shorter in the asymptomatic PHPT patients than that in the symptomatic PHPT patients (median 12 months vs 24 months, P=0.004). The serum calcium, the albumin-corrected serum calcium, and parathyroid hormone (PTH) were lower in the asymptomatic PHPT patients than those in the symptomatic PHPT (P=0.003, P=0.006, and P=0.042, respectively). The serum 1,25-dihydroxyvitamin D₃ was higher (P<0.001), the diameter was shorter (P=0.028), and the bone mineral densities (BMD) of L_2~4 and femoral neck were higher in the asymptomatic PHPT patients than those in the symptomatic PHPT patients (both P<0.001).

Only a minority of PHPT patients are asymptomatic. Compared with the symptomatic PHPT patients, the primary cause of diagnosis is hypercalcemia, the duration of diagnosis and the diameter of parathyroid gland are shorter, the levels of serum calcium, and PTH are lower, the proportion of adenomas, vitamin D, and the BMD of L_2-4 and femoral neck are higher, and the pathological type is benign in the asymptomatic PHPT patients.