title: Surgery or no surgery: What works best for the kidneys in primary hyperparathyroidism? A study in a multi-ethnic Asian population.
abstract: BACKGROUND
  Whether parathyroidectomy is more beneficial to renal function when compared to medical therapy or observation in primary hyperparathyroidism (PHPT) is unclear. Neither has this premise been explored in non-Caucasian populations. The estimated glomerular filtration rate (eGFR) threshold below which parathyroid hormone (PTH) levels rise if at all in PHPT has also not been established. We determined if surgery was superior to medical therapy and observation in a multi-ethnic Asian patient population with PHPT and whether there was an eGFR threshold below which PTH levels further increased in them.
  
  
  METHODS
  Retrospective evaluation of patients with PHPT.
  
  
  RESULTS
  There were 68.6% Chinese, 17.4% Malays, 10.7% Indians, and 3.3% Eurasians. The median (interquartile range) follow-up was 18.0 months (4.5-46.8). At last follow-up, eGFR in the surgical (80 ± 30 ml/min) was higher than the medical (52 ± 32 ml/min) or observation groups (48 ± 33 ml/min); P < 0.01. This difference persisted after adjusting for age, gender, ethnicity, pre-intervention eGFR levels, nephrolithiasis, serum calcium, phosphate, urinary calcium, and duration of follow-up; P = 0.035. There was no definite eGFR level below which PTH values rose.
  
  
  CONCLUSIONS
  Our study provides compelling evidence that in PHPT, surgery may be associated with a better renal outcome compared to medical management or observation. This has to be confirmed through prospective randomized controlled trials and the reasons for this finding have to be elucidated through functional and histological measures. The finding in our study of a lack of a specific eGFR threshold below which PTH levels further rose challenges the concept of a fixed renal threshold for secondary elevations of PTH in PHPT.
authors.affiliation: Osteoporosis and Bone Metabolism Unit, Department of Endocrinology, Singapore General Hospital, Singapore.
authors.forename: Yu Kwang Donovan
authors.initials: YK
authors.lastname: Tay
authors.affiliation: Department of Endocrinology, Changi General Hospital, Singapore.
authors.forename: Joan
authors.initials: J
authors.lastname: Khoo
authors.affiliation: Osteoporosis and Bone Metabolism Unit, Department of Endocrinology, Singapore General Hospital, Singapore.
authors.forename: Manju
authors.initials: M
authors.lastname: Chandran
keywords: Creatinine clearance; estimated glomerular filtration rate threshold; parathyroidectomy; primary hyperparathyroidism; renal function