title: Vitamin C deficiency and secondary hyperparathyroidism in chronic haemodialysis patients.
abstract: BACKGROUND
  Maintenance haemodialysis patients often suffer from secondary hyperparathyroidism and serum parathyroid hormone levels may be influenced by nutritional variables.
  
  
  METHODS
  We examined serum bio-intact parathyroid hormone (BiPTH) and plasma vitamin C in 117 chronic haemodialysis patients. Plasma vitamin C was measured by high-performance liquid chromatography with electrochemical detection, on samples collected before start of the dialysis treatment.
  
  
  RESULTS
  Plasma vitamin C showed a significant positively skewed distribution, ranging from <2 microM to >300 microM. We found 15% (n = 17) of the patients with severe vitamin C deficiency (<10 microM), 66% (n = 77) in the range 10-80 microM, and 19% (n = 23) with plasma vitamin C >80 microM, the upper limit of normal for non-renal disease population. High plasma vitamin C was associated with lower plasma BiPTH (P = 0.005, one-way analysis of variance), and this association persisted after stepwise multiple regression for other factors known to influence PTH. Low vitamin C levels were also associated with increased serum alkaline phosphatase, a further indicator of the impact of vitamin C status on bone metabolism. Patients who reported dietary vitamin C intake of >or=100 mg/day had lower BiPTH (P = 0.015), consistent with findings from plasma measurements of vitamin C. This novel observation of the interaction between PTH and vitamin C may result from effects of vitamin C on cAMP-linked signalling pathways in bone and parathyroid gland.
  
  
  CONCLUSIONS
  This finding does not yet warrant therapeutic intervention with supplemental vitamin C to remedy secondary hyperparathyroidism. However, further research may indicate a key interaction between vitamin C and the parathyroid hormone linked signalling pathways, and may uncover mechanisms of therapeutic importance.
authors: Renal Research Institute, 207 East 94th Street, Suite 303, New York, NY 10128, USA. anjarich@gmail.com
authors: Anja
authors: A
authors: Richter
authors: Martin K
authors: MK
authors: Kuhlmann
authors: Eric
authors: E
authors: Seibert
authors: Peter
authors: P
authors: Kotanko
authors: Nathan W
authors: NW
authors: Levin
authors: Garry J
authors: GJ
authors: Handelman
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001206:Ascorbic Acid Deficiency / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D012080:Chronic Kidney Disease-Mineral and Bone Disorder / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D015994:Incidence; D016014:Linear Models; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D011336:Probability; D011379:Prognosis; D006435:Renal Dialysis / Q000009:adverse effects* / Q000379:methods; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D016019:Survival Analysis
chemical_list: D010281:Parathyroid Hormone