Primary Hyperparathyroidism – A Contemporary Picture Based on 100 Patients from the Last Decade
Authors: Boyanov M. , Bakalov D. , Karamfilova V. , Gateva A. , Assyov Y. , Zaharieva E. , Atanassova K. , Sheinkova G. , Tsakova A. , Kamenov Z. 
Published: August 2021

Abstract
Primary hyperparathyroidism (PHPT) is an endocrine disease, the clinical picture of which has slowly shifted to milder and asymptomatic forms during the last decades.

Objective
to describe the clinical presentation and the main laboratory and imaging findings in a group of patients with PHPT diagnosed during the last 10 years.

Materials and Methods
This was a retrospective cross-sectional study with data review from the database of a tertiary endocrine clinic from the last 10 years. Secondary causes for elevated PTH were excluded. The major clinical symptoms and signs of hypercalcemia/HPT were reviewed as well as concomitant diseases and medications. Serum calcium (total, albumin-corrected and ionized; sCa, corrCa, iCa+), phosphates (P), magnesium, creatinine, alkaline phosphatase, beta-crosslinks were measured. The intact parathyroid hormone (iPTH) and 25(OH)-vitamin D were determined by electro-hemi-luminescence (Elecsys, Roche Diagnostics). 24-hour urinary probes for calcium and phosphate were collected. Neck ultrasound (US) was used as the localization study of choice. Almost half of the participants underwent fine-needle aspiration biopsy (FNAB) with cytology and needle-washouts for iPTH. One fourth of the patients were assessed by Single-Photon Emission Tomography (SPECT-CT). Data on bone density (from DXA), fractures and renal stones (from renal US) were collected.

Results
One hundred patients met the study criteria – 95 were women. Most of them were in their 5th and 6th decades. The median corrected sCa was 2.73 mmol/l, iCa+ – 1.39 mmol/l, P – 0.88 mmol/l, iPTH – 14.5 pmol/l and 25(OH)D – 54.0 nmol/l. Normal sCa was registered in 20 participants (20%), while normal sP – in 67.0%. The neck US located single lesions (parathyroid adenoma) in 81% – behind or below the left inferior pole of the thyroid gland in 33 cases (33%) and contra-laterally in another 33%. FNAB of the suspicious lesion had been performed in 51% of the study subjects. The cytology confirmed the presence of parathyroid cells in 22 cases (43.1%), Bethesda II thyroid nodules in 21 cases (41.2%), Bethesda III nodules in 2 cases (3.9%) and insufficient samples (Bethesda I) in 5 cases (9.8%). SPECT-CT from 27 patients identified a suspicious left parathyroid in 11 cases, a right one – in 6 cases, as well as three ectopic locations. BMD data were available in 66 female patients and showed a higher prevalence of osteoporosis than in the general age-matched population; fractures, however, were not more frequent. Data from renal ultrasound were available in 77% and revealed chronic pyelonephritis without stones in 8 patients and renal stone disease – in 37 patients.

Conclusion
To our knowledge, this study is the first of its kind in our country during the last two decades. Mild to moderate hypercalcemia was very common, although most patients were oligoor asymptomatic. Renal and bone involvement were surprisingly frequent, with reduced eGFR and low bone mass being more prevalent than in the general population. The most typical location was a single parathyroid lesion within the lower glands. The use of SPECT-CT seems to decline and is replaced by US-guided FNAB with needle washout measurements of iPTH and cytological examination. Although the general picture of PHPT is shifting towards milder and asymptomatic (and probably earlier) forms of the disease, the classical clinical presentation can still be found in everyday practice.