title: Is Preoperative Vitamin D Deficiency a Risk Factor for Postoperative Symptomatic Hypocalcemia in Thyroid Cancer Patients Undergoing Total Thyroidectomy Plus Central Compartment Neck Dissection?
abstract: BACKGROUND
  Although some studies have reported that preoperative vitamin D deficiency (VDD) is a risk factor for hypocalcemia after total thyroidectomy (TT) in patients with nontoxic multinodular goiter or Graves' disease, the association between VDD and postoperative hypocalcemia in thyroid cancer patients undergoing TT plus central compartment neck dissection (CCND) remains unclear. This study evaluated whether preoperative VDD was associated with postoperative symptomatic hypocalcemia.
  
  
  METHODS
  Data were collected prospectively between September 2012 and May 2013. A total of 267 consecutive thyroid cancer patients who underwent TT with CCND were analyzed. Patients were divided into two groups--VDD or non-VDD--by preoperative vitamin D level of <10 or ≥10 ng/mL. Symptomatic hypocalcemia was defined as serum calcium <8.2 mg/dL and symptoms or signs of hypocalcemia. The rates of postoperative symptomatic hypocalcemia and clinicopathological features were compared between the two patient groups.
  
  
  RESULTS
  The rate of postoperative symptomatic hypocalcemia was higher in the VDD group than in the non-VDD group (43.8% vs. 30.4%, p=0.043). By logistic regression analysis, predictive factors for postoperative symptomatic hypocalcemia included a preoperative vitamin D level of <10 ng/mL (p=0.007; odds ratio=3.00). In patients who had postoperative intact parathyroid hormone (iPTH) levels <15 pg/mL, symptomatic hypocalcemia was more common in the VDD group than in the non-VDD group (77.5% vs. 53.2%, p=0.008). The findings show that a preoperative vitamin D threshold level of >20 ng/mL reduced the risk of symptomatic hypocalcemia by 72% when compared with patients with VDD (p=0.003).
  
  
  CONCLUSIONS
  VDD is significantly associated with postoperative symptomatic hypocalcemia in thyroid cancer patients undergoing TT plus CCND. VDD was predictive for symptomatic hypocalcemia when patients had postoperative serum iPTH levels <15 pg/mL. Thus, preoperative supplementation with oral vitamin D should be considered to minimize postoperative symptomatic hypocalcemia.
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Won Woong
authors.initials: WW
authors.lastname: Kim
authors.affiliation: 2 Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea , Seoul, Korea.
authors.forename: So-Hyang
authors.initials: SH
authors.lastname: Chung
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Eun Jeong
authors.initials: EJ
authors.lastname: Ban
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Cho Rok
authors.initials: CR
authors.lastname: Lee
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Jong Ju
authors.initials: JJ
authors.lastname: Jeong
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Kee-Hyun
authors.initials: KH
authors.lastname: Nam
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Woong Youn
authors.initials: WY
authors.lastname: Chung
authors.affiliation: 1 Department of Surgery, Institute of Endocrine Research, Yonsei University Health System , Seoul, Korea.
authors.forename: Cheong Soo
authors.initials: CS
authors.lastname: Park
mesh_terms: D000328:Adult; D002118:Calcium / Q000097:blood; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood* / Q000473:pathology; D007297:Inpatients; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection; D010280:Parathyroid Glands / Q000473:pathology; D010281:Parathyroid Hormone / Q000097:blood; D011183:Postoperative Complications; D011184:Postoperative Period; D057234:Preoperative Period; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000097:blood* / Q000601:surgery; D013965:Thyroidectomy; D014807:Vitamin D / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; D002118:Calcium