Endocrine Abstracts

Introduction: Primary hyperparathyroidism (PHPT) patients who undergo parathyroidectomy can develop isolated intact parathormone (iPTH) elevation with normal calcemia. Common causes are: renal insufficiency (RI), vitamin D deficit and hypomagnesemia.

Aim: To identify clinical factors associated with iPTH elevation in patients submitted to surgery treatment.

Methods: The medical records of patients admitted into Santo António’s Hospital between January/2000 and July/2011 with ICD-9 diagnosis of ‘Hyperparathyroidism’, ‘Complete Hyperparathyroidectomy’ and ‘Other Hyperparathyroidectomy’ were reviewed. Patients who underwent surgery and had post-operative iPTH elevation and eucalcemia were selected. Demographical and clinical data was collected.

Results: There were 82 patients who underwent surgery treatment, 31.7% (n=26) of them had at least one elevated iPTH level throughout the fallow-up. This group consisted mainly of women (76.9%) with a mean age of 58.3±14 years old at surgery. Eleven patients (42.3%) had high iPTH levels since the first measurement after surgery. In 18 patients (69.2%) there was at least one reason for iPTH elevation: 77.8% had low vitamin D levels; 23.5% had hypomagnesemia; 23.1% had RI (creatinine=2.5±1.4 mg/dl). Three patients had MEN-1 mutation.

At last evaluation (mean follow-up of 4.1±3.4 years) 13 patients maintained iPTH levels above normal range (111.1±59.1 pg/ml, 67–260). Four patients maintained RI, 6 low vitamin D levels and 1 hypomagnesemia. There was no analytical, surgical or pathological differences between these patients and those with iPTH levels normalization.

Discussion and conclusions: Almost 1/3 of the PHPT patients submitted to parathyroidectomy had post-operative iPTH elevation mainly because of vitamin D deficit, hypomagnesemia or RI. The authors emphasize the need to identify those factors that may increase iPTH levels, and to monitor those who, despite supplementation, maintain iPTH elevation because of risk for persistent or recurrent PHPT.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.