The Normohormonal Primary Hyperparathyroidism; a surgical dilemma pre and intra-operatively

Normohormonal Primary Hyperparathyroidism (NPHPT), poses a dilemma for surgeons; first in deciding when to operate where the PTH is normal and second at what level should the drop in intra-operative PTH (ioPTH) be considered a successful operation.

A retrospective evaluation of all parathyroidectomies performed by a single surgeon from 2009 to 2019 was conducted.

In 33 of 349 (9%) parathyroidectomies the indication was NPHPT. Negative pre-operative nuclear localization was found in 17(52%) patients. Intra-operative findings were: 27(82%) single-adenoma, 3(9%) double-adenomas and 3(9%) hyperplasia. In patients with single-adenomas the ioPTH dropped from 57 ± 8 to 23 ± 10 pg./ml. The average size of the adenomas was 403 ± 360 mg.

NPHPT is uncommon where the disease is diagnosed in its early stages. Over 50% has negative pre-operative nuclear localization test requiring 4-gland surgical exploration. The intra-operative drop in PTH below 30 pg./ml can be utilized as an indicator of a successful operation.