Normocalcaemic hyperparathyroidism: a modern entity or iatrogenic? — ASN Events
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Normocalcaemic hyperparathyroidism: a modern entity or iatrogenic? (#380)

Tharani Ramasamy 1 , Anna Anderson 1 2
  1. Barwon Health, Geelong, VIC, Australia
  2. Deakin University, Geelong, Australia

Background

Normocalcaemic hyperparathyroidism (nPHPT) is a recently recognised clinical entity, formally defined at the Third International Workshop in the Management of Asymptomatic Primary Hyperparathyroidism in 20081. It is characterised by persistently elevated parathyroid hormone levels (PTH) in the presence of consistently normal calcium concentrations and in the absence of secondary causes of PTH elevation. It’s growing recognition is attributable to increased routine PTH measurement during assessment of metabolic bone disease. A causative link between nPHPT and end-organ disease usually associated with primary hyperparathyroidism (osteoporosis and nephrolithiasis), remains unclear.

This study aims to identify potential associations between PTH, demographics, biochemical data and medications which may influence calcium metabolism as potential factors in the development of nPHPT.

Method

All patients with nPHPT were identified from the Public Endocrine clinic, Geelong Hospital specified as having PTH >8.5 pmol/L, normal calcium (2.1-2.6 mmol/L), vitamin D > 50 nmol/L and normal renal function (eGFR > 60 ml/min/1.73m2). Demographic data, biochemical data and concomitant medications which potentially influence calcium metabolism were recorded. Data was analysed using SPSS V30.

Results

58 patients were identified as having nPHPT. Mean age 63.7 years (range 25-88 years). The majority were female (74%). Mean PTH 18.35 pmol/L (SD 3.9), calcium 2.42 mmol/L (SD 0.1), Vitamin D 79.0 nmol/L (SD 18.5) and eGFR 78.6 ml/min/1.73m2 (SD 10.2). A significant correlation was observed between age (in decades) and PTH (ANOVA p<0.001). A significant negative correlation was observed between age and eGFR (Pearson’s correlation p=0.005). Multivariate ANOVA was used to assess the influence of medication, with loop diuretics showing a trend to increase PTH concentrations (p=0.77) and PPI having a significant correlation with serum calcium concentrations (p=0.33).

Conclusions

Through alteration in calcium absorption and excretion, PPIs and loop diuretic medications along with age should be considered as factors in the development of nPHPT.

  1. Zavatta G, Clarke BL. Normocalcemic Primary Hyperparathyroidism: Need for a Standardized Clinical Approach. Endocrinol Metab (Seoul) 2021;36(3):525-35. doi: 10.3803/EnM.2021.1061 [published Online First: 20210601]