The effect of parathyroidectomy compared to non-surgical surveillance on kidney function in primary hyperparathyroidism: a nationwide historic cohort study

Josephine Matzen,Pia Eiken,Bo Abrahamsen,Tanja Sikjær,Lars Rejnmark,Anne Pernille Hermann,Lise Sofie Bislev,Lars Rolighed,Mette Friberg Hitz,Jens-Erik Beck Jensen

doi:10.1186/s12902-021-00918-z

Abstract

BackgroundPatients with primary hyperparathyroidism (pHPT) and impaired kidney function (estimated glomerular filtration rate (eGFR) < 60 mL/min) are offered parathyroidectomy (PTX) to protect them from further complications. Surprisingly, two recent uncontrolled cohort studies have suggested a further decrease in kidney function following PTX. We aimed to examine the effects of PTX compared to non-surgical surveillance on kidney function in pHPT patients.MethodsHistoric cohort study. From the Danish National Patient Registry (NPR) and major medical biochemistry laboratories in Denmark, we identified 3585 patients with biochemically confirmed pHPT among whom n = 1977 (55%) were treated with PTX (PTX-group) whereas n = 1608 (45%) were followed without surgery (non-PTX group). Baseline was defined as time of diagnosis and kidney function was re-assessed 9–15 months after PTX (PTX group) or 9–15 months after diagnosis (non-PTX group).ResultsAt follow-up, eGFR had decreased significantly in the PTX- compared to the non-PTX-group (median − 4% vs. − 1%, p < 0.01). Stratification by baseline eGFR showed that the decrease was significant for those with a baseline eGFR value of 80–89 and > 90 mL/min, but not for those with lower eGFR values. Findings did not differ between patients with mild compared to moderate/severe hypercalcemia. However, after mutual adjustments, we identified baseline levels of calcium, PTH, and eGFR as well as age and treatment (PTX vs. no-PTX) as independent predictors for changes in kidney function.ConclusionCompared to non-surgical surveillance, PTX is associated with a small but significant decrease in kidney function in pHPT patients with an initial normal kidney function.

Highlights

Patients with primary hyperparathyroidism and impaired kidney function (estimated glomerular filtration rate < 60 mL/min) are offered parathyroidectomy (PTX) to protect them from further complications
Using the National Patient Registry (NPR), we identified all patients assigned a hospital discharge code of hyperparathyroidism according to the International Classification of Diseases (ICD) between 1977 and June 2015
Whereas previous studies showed that PTX is associated with a decline in kidney function only if Estimated glomerular filtration rate (eGFR) at baseline is above 60 mL/min, but not if eGFR at baseline is below 60 mL/min, our analyses suggest that the decline in kidney function following PTX only applies to those with a baseline eGFR above 80 mL/min

Summary

Introduction

Patients with primary hyperparathyroidism (pHPT) and impaired kidney function (estimated glomerular filtration rate (eGFR) < 60 mL/min) are offered parathyroidectomy (PTX) to protect them from further complications. Primary hyperparathyroidism (pHPT) is an endocrine disease caused by parathyroid hormone (PTH) producing adenoma or hyperplasia in one or more of the 4 parathyroid glands [1]. PTH levels are augmented due to decreased responsiveness of the glands to the normal negative feedback system via calcium-sensing receptors. PHPT is defined biochemically by hypercalcemia and elevated or inappropriately normal levels of PTH [1]. If plasma calcium levels are only mildly elevated it remains an open question whether patients benefit from surgery, guidelines recommend PTX if patients suffer from e.g., osteoporosis or kidney diseases [3, 4]

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