title: Utility of baseline serum phosphorus levels for predicting remission in acromegaly patients.
abstract: OBJECTIVE
  High GH and IGF I levels increase tubular phosphate reabsorption in patients with acromegaly. We aimed to investigate the utility of serum phosphorus levels as an indicator for predicting chance of remission in acromegaly patients.
  
  
  METHODS
  Fifty-one patients (n: 51; F: 24, M: 27) with diagnosis of acromegaly were included in the study. Plasma IGF-1, Phosphorus (P) and nadir GH levels on oral glucose tolerance test (OGTT) at the time of diagnosis were analysed retrospectively. Patients were classified into two groups according to their plasma P levels; P ≤ 4.5 mg/dl (Group-1, n: 23, 45.1%), P > 4.5 mg/dl (Group-2, n: 28, 54.9%). Two groups were compared according to remission status; remission (n: 27) and non-remission (n: 24). Remission was defined with absence of clinical symptoms, normal plasma IGF-1 (adjusted for age and gender) and GH levels (<1 mcg/dl) at least 3 months after initial treatment.
  
  
  RESULTS
  Serum P levels decreased significantly after treatment in both groups (p < 0.001). There was a significant correlation between baseline phosphorus levels and remission rates, nadir GH in OGTT, pituitary adenoma size and Ki-67 scores (p = 0.001, r: -0.51; p = 0.01, r: 0.44; p = 0.001, r: 0.52; p = 0.02, r: 0.71, respectively). Mean baseline P levels were significantly higher in patients with non-remission (4.8 vs 4.2, P < 0.001). Logistic regression analysis did not reveal an independent effect on remission with any of these risk factors.
  
  
  CONCLUSIONS
  High serum P levels may be an indicator for a low likelihood of onset of remission in acromegaly patients. Further studies with wider spectrum are needed to make specific suggestions.
authors.affiliation: Division of Endocrinology and Metabolism Disorders, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34090, Istanbul, Turkey. gulsah_y@hotmail.com.
authors.forename: G Y
authors.initials: GY
authors.lastname: Yalin
authors.affiliation: Division of Endocrinology and Metabolism Disorders, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34090, Istanbul, Turkey.
authors.forename: S
authors.initials: S
authors.lastname: Tanrikulu
authors.affiliation: Division of Endocrinology and Metabolism Disorders, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34090, Istanbul, Turkey.
authors.forename: N
authors.initials: N
authors.lastname: Gul
authors.affiliation: Division of Endocrinology and Metabolism Disorders, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34090, Istanbul, Turkey.
authors.forename: A K
authors.initials: AK
authors.lastname: Uzum
authors.affiliation: Division of Endocrinology and Metabolism Disorders, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34090, Istanbul, Turkey.
authors.forename: F
authors.initials: F
authors.lastname: Aral
authors.affiliation: Division of Endocrinology and Metabolism Disorders, Department of Internal Medicine, Istanbul Faculty of Medicine, Istanbul University, Capa, 34090, Istanbul, Turkey.
authors.forename: R
authors.initials: R
authors.lastname: Tanakol
mesh_terms: D000172:Acromegaly / Q000097:blood* / Q000628:therapy; D000328:Adult; D015415:Biomarkers / Q000097:blood*; D005260:Female; D005951:Glucose Tolerance Test; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D010758:Phosphorus / Q000097:blood*; D012074:Remission Induction; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; C583557:IGF1 protein, human; D019382:Human Growth Hormone; D010758:Phosphorus; D007334:Insulin-Like Growth Factor I
keywords: Acromegaly; IGF-1; Phosphorus; Remission