title: Intra-operative parathyroid hormone kinetics and influencing factors with high baseline PTH: a prospective study.
abstract: OBJECTIVE
  Intra-operative parathyroid hormone (IOPTH) kinetics and therefore the efficacy of IOPTH utilization as a predictor of cure are likely to be affected by baseline IOPTH levels, vitamin D deficiency and parathyroid weight.
  
  
  METHODS
  Consecutive subjects with primary hyperparathyroidism (PHPT, n = 51) undergoing parathyroidectomy with IOPTH monitoring were studied prospectively during the period October 2009-November 2011. Samples were collected pre-incision, pre-excision and post-excision (5, 10, 15 min). Iterative analysis of IOPTH kinetics and half-life calculation was carried out in subgroups. Nonparametric testing was used for group statistics.
  
  
  RESULTS
  Hypovitaminosis D (25(OH)D3 < 50 nm) was present in 39 (76%), serum PTH > 1000 ng/l in 23 (45%), and giant parathyroid adenoma (weight > 3000 mg) in 23 (45%). The percentage drop at 10 min was significantly higher in large adenomas (weight > 3000 mg). Miami and 5 min criteria showed the highest negative predictive value and maximum accuracy. The average percentage IOPTH drop observed at 5 min post-excision was 79.8%. Kinetic analysis showed a mean half-life of PTH of 2.57 ± 0.27 min (range: 0.07-11.55).
  
  
  CONCLUSIONS
  IOPTH monitoring is reliable even in patients with extremely high baseline IOPTH value, with a greater percentage drop at 5 and 10 min post-excision. In patients with high baseline IOPTH, a 50% decay in PTH value at 5 min may be indicative of cure, obviating the need for 10 and 15 min samples. IOPTH kinetics are altered by adenoma weight but not affected by vitamin D status or baseline IOPTH levels.
authors.affiliation: Department of Endocrine Surgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences, India.
authors.forename: Dependra N
authors.initials: DN
authors.lastname: Singh
authors.forename: Sushil K
authors.initials: SK
authors.lastname: Gupta
authors.forename: Gyan
authors.initials: G
authors.lastname: Chand
authors.forename: Anjali
authors.initials: A
authors.lastname: Mishra
authors.forename: Gaurav
authors.initials: G
authors.lastname: Agarwal
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Verma
authors.forename: Saroj Kanta
authors.initials: SK
authors.lastname: Mishra
authors.forename: Manoj
authors.initials: M
authors.lastname: Shukla
authors.forename: Amit
authors.initials: A
authors.lastname: Agarwal
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006207:Half-Life; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood* / Q000601:surgery; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010281:Parathyroid Hormone / Q000097:blood*; D010282:Parathyroid Neoplasms / Q000097:blood* / Q000601:surgery; D016105:Parathyroidectomy; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014808:Vitamin D Deficiency / Q000601:surgery
chemical_list: D010281:Parathyroid Hormone