Post-parathyroidectomy serum phosphate kinetics is peculiar to female hemodialysis patients with a high body mass index.
BACKGROUND
Persistent hyperphosphatemia is one of the most important factors in the development of secondary hyperparathyroidism (sHPTH). Recently, we demonstrated that a higher body mass index (BMI) and female gender could predispose to a larger phosphate (P) body burden, thereby influencing the severity of sHPTH.


METHODS
This prospective study aimed to verify if these two risk factors, i.e. BMI and female gender, also influenced calcium (Ca) and P kinetics in the immediate post-parathyroidectomy (PTx) period in 42 consecutive adult Caucasian anuric hemodialysis (HD) patients referred for first PTx. Serum Ca and P were measured pre-PTx and on the 5 consecutive post-PTx days; serum immunoreactive parathyroid hormone (iPTH) and alkaline phosphatase (ALP) levels were measured pre-PTx and 3 days post-PTx.


RESULTS
Ablation of parathyroid tissue determined a significant reduction in serum iPTH, ALP, Ca and P (p = 0.001). The stratification of the cohort into four groups according to the cut-off value of BMI = 25 kg/m(2) and according to gender showed the following: males and females with BMI >25 kg/m(2) (analyzed both separately and as a subgroup including males and females) had significantly higher pre-PTx serum P levels, when compared with the respective sub-groups with BMI <25 kg/m(2) (p < 0.01); a significantly higher mean area under the concentration curve (AUC) of serum P was observed in the high BMI group (males and females), when compared with the low/normal BMI group (p = 0.03); the serum P kinetics in the 5 post-PTx days did not differ between the two groups of male patients (low/normal BMI males vs. high BMI males), whereas a significantly higher mean serum P AUC was observed in the high BMI female patients, when compared with the low/normal BMI female patients (p = 0.003); finally, the serum P kinetics in the 5 post-PTx days did not differ between the two groups of low/normal male and female patients, whereas a significantly higher mean serum P AUC was observed in the high BMI female patients, when compared with the high BMI male patients (p = 0.006). A linear multiple regression analysis with the serum P AUC of each patient as a dependent variable and BMI, gender, age and dialysis duration as independent variables showed that BMI (p = 0.0001) and female gender (p = 0.001) were independent predictors of the serum P AUC.


CONCLUSIONS
High BMI and female gender are associated with peculiar serum P kinetics in the immediate post-PTx period, suggesting the existence of a larger P body burden in high BMI female HD patients. The existence of a larger P pool exclusively based on serum P kinetics prompts the need for further studies to better understand such intriguing aspects of bone pathophysiology in response to parathyroid gland removal in chronically uremic patients.
Lomonte
Carlo
C
Division of Nephrology, Miulli General Hospital, Acquaviva delle Fonti, Bari, Italy.
Vernaglione
Luigi
L
Cazzato
Francesco
F
Casucci
Francesco
F
Chimienti
Domenico
D
Bruno
Andrea
A
Cocola
Savino
S
Basile
Carlo
C
D000328:Adult; D001002:Anuria / Q000097:blood* / Q000628:therapy; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000209:etiology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016105:Parathyroidectomy; D010710:Phosphates / Q000097:blood*; D011184:Postoperative Period; D011379:Prognosis; D011446:Prospective Studies; D006435:Renal Dialysis / Q000009:adverse effects*; D012307:Risk Factors; D012737:Sex Factors
D015415:Biomarkers; D010710:Phosphates