title: Evaluation of the parathyroid function in six patients with hypophosphatemic osteomalacia, including a case of tertiary hyperparathyroidism developing during combined oral phosphate and vitamin D therapy.
abstract: OBJECTIVE
  To describe a case of tertiary hyperparathyroidism after long-term phosphate and vitamin D therapy and the retrospective evaluation of parathyroid function in 6 patients with hypophosphatemic osteomalaica.
  
  
  METHODS
  We evaluated the parathyroid function by measuring iPTH before and during treatment and divided the patients into normal and elevated serum iPTH groups.
  
  
  RESULTS
  In the normal serum iPTH group, the 4 patients were all males, whereas the 2 patients in the elevated serum iPTH group were females. Clinical characteristics and biochemical results showed no differences between the two groups. One of the women with an elevated iPTH level (224 pg/ml) had a normal serum calcium level and no evidence of increasing parathyroid uptake by (99m)Tc-MIBI scan 52 months after treatment. The other woman also had an elevated iPTH level (483 pg/ml) and a normal serum calcium level 56 months after treatment. However, in this latter case both her iPTH (1,447 pg/ml) and serum calcium (11.3 mg/dl) levels were elevated 113 months after treatment, when a (99m)Tc-MIBI scan showed increased uptake in all four parathyroid glands during early and delayed phases of the scan. Parathyroidectomy was performed after the diagnosis of tertiary hyperparathyroidism was made, and the histological findings showed adenomatous hyperplasia.
  
  
  CONCLUSIONS
  Our findings indicate that even with vitamin D therapy, long-term phosphate therapy may lead to the development of secondary or tertiary hyperparathyroidism in hypophosphatemic osteomalacia and, therefore, suggest that it is important to carefully monitor the parathyroid function during therapy in those with hypophosphatemic osteomalacia.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Jeon
authors.forename: Seong Hee
authors.initials: SH
authors.lastname: Kwon
authors.forename: Sang Wan
authors.initials: SW
authors.lastname: Kim
authors.forename: Chan Soo
authors.initials: CS
authors.lastname: Shin
authors.forename: Kyung Soo
authors.initials: KS
authors.lastname: Park
authors.forename: Seong Yeon
authors.initials: SY
authors.lastname: Kim
authors.forename: Bo Yeon
authors.initials: BY
authors.lastname: Cho
authors.forename: Hong Kyu
authors.initials: HK
authors.lastname: Lee
mesh_terms: D000328:Adult; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000139:chemically induced*; D017674:Hypophosphatemia / Q000150:complications*; D008297:Male; D008875:Middle Aged; D010018:Osteomalacia / Q000209:etiology* / Q000503:physiopathology*; D010280:Parathyroid Glands / Q000503:physiopathology*; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000009:adverse effects*; D014807:Vitamin D / Q000627:therapeutic use*
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D