Correlates of parathyroid hormone concentration in hemodialysis patients.
BACKGROUND
The implications of chemical hyperparathyroidism on bone and mineral metabolism measures in maintenance hemodialysis (MHD) are not well known. We hypothesized that a higher serum intact parathyroid hormone (iPTH) level is associated with the higher likelihood of hyperphosphatemia, hyperphosphatasemia [high serum alkaline phosphatase (ALP) levels] and hypercalcemia.


METHODS
Over an 8-year period (July 2001-June 2009), we identified 106 760 MHD patients with iPTH and calcium (Ca), phosphorous (P) and ALP data from a large dialysis clinic. Logistic regression models were examined to assess the association between serum iPTH increments and the likelihood of hyperphosphatemia (P ≥5.5 mg/dL), hypercalcemia (Ca ≥10.2 mg/dL) and hyperphosphatasemia (ALP ≥120 U/L).


RESULTS
Patients were 61 ± 16 years old and included 45% women, 59% diabetics and 33% Blacks. Compared with an iPTH level of 100 to <200 pg/mL, patients with an iPTH level of 600-700, 700 to <800 and ≥800 pg/mL had 122% (OR: 2.22, 95% CI: 2.04-2.41), 153% (OR: 2.53, 95% CI: 2.29-2.80) and 243% (OR: 3.43, 95% CI: 3.22-3.66) higher risk of hyperphosphatemia, respectively, and had 109% (OR: 2.09, 95% CI: 1.93-2.26), 130% (OR: 2.30, 95% CI: 2.10-2.52) and 376% (OR: 4.76, 95% CI: 4.50-5.04) higher risk of hyperphosphatasemia, respectively. Compared with an iPTH level of 100 to <200 pg/mL, both the low iPTH (<100 pg/mL, OR: 2.45, 95% CI: 2.27-2.64) and the high iPTH (≥800 pg/mL: OR: 2.13, 95% CI: 1.95-2.33) levels were associated with hypercalcemia.


CONCLUSIONS
Higher levels of iPTH are incremental correlates of hyperphosphatemia and hyperphosphatasemia, whereas both very low and high PTH levels are linked to hypercalcemia. If these associations are causal, correction of hyperparathyroidism may have overarching implications on bone and mineral disorders in MHD patients.
Harold Simmons Center for Chronic Disease Research and Epidemiology, University of California Irvine Medical Center, Irvine, CA, USA.
Jinnan
J
Li
Miklos Z
MZ
Molnar
Joshua J
JJ
Zaritsky
John J
JJ
Sim
Elani
E
Streja
Csaba P
CP
Kovesdy
Isidro
I
Salusky
Kamyar
K
Kalantar-Zadeh
D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D002118:Calcium / Q000097:blood; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000097:blood / Q000209:etiology*; D006961:Hyperparathyroidism / Q000097:blood / Q000209:etiology*; D054559:Hyperphosphatemia / Q000097:blood / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood; D011379:Prognosis; D006435:Renal Dialysis / Q000009:adverse effects*; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications*; D012307:Risk Factors
D015415:Biomarkers; D010281:Parathyroid Hormone; D010758:Phosphorus; D000469:Alkaline Phosphatase; D002118:Calcium
hemodialysis; serum alkaline phosphatase; serum calcium; serum intact parathyroid hormone; serum phosphorous