Parathyroid hormone suppression by intravenous calcitriol: role of phosphate, calcium, race and diabetes

Mineral metabolism and cardiovascular morbidity and mortality risk: peritoneal dialysis patients compared with haemodialysis patients

BACKGROUND

The K/DOQI guideline for bone metabolism and disease in chronic kidney disease is predominantly based on studies in haemodialysis (HD) patients. However, in clinical practice, this guideline is also applied to peritoneal dialysis (PD) patients. To validate the implementation of this guideline in PD patients, we evaluated the associations between plasma concentrations outside the K/DOQI-targets and the risk of cardiovascular morbidity and mortality in incident PD patients compared with HD patients.

METHODS

In a large prospective multicentre study in the Netherlands (The Netherlands Cooperative Study on the Adequacy of Dialysis, NECOSAD), we included patients starting PD or HD between 1997 and 2004. Relative risk of cardiovascular morbidity and mortality were estimated using time-dependent Cox regression modelling.

RESULTS

We included 586 PD patients with mean age 52 +/- 15 years (66% males) and 1043 HD patients with mean age 63 +/- 14 years (58% males). Cardiovascular disease (CVD) was the reason for hospitalization in 102 PD and 271 HD patients. In HD patients, the relative risk of CVD-related hospitalization increased with elevated plasma calcium concentrations (hazard ratio: 1.4; 95% CI: 1.1-1.9). Cardiovascular mortality was significantly higher for phosphorus concentrations above the K/DOQI-threshold in PD (2.4; 95% CI: 1.3-4.2) and HD patients (1.5; 95% CI: 1.1-2.1), and for elevated Ca x P in PD (2.2; 95% CI: 1.3-3.8) and HD patients (1.5; 95% CI: 1.1-2.1).

CONCLUSIONS

Plasma calcium concentrations above the K/DOQI-threshold increase the relative risk of CVD-related hospitalization in HD patients. Associations with cardiovascular mortality were more pronounced. Both in PD and HD patients with elevated plasma phosphorus and Ca x P concentrations, the cardiovascular mortality risk is increased. Therefore, it seems appropriate to adopt the current guideline in PD patients.

The Kidney Disease Outcomes Quality Initiative (K/DOQI) Guideline for Bone Metabolism and Disease in CKD: association with mortality in dialysis patients

BACKGROUND

In 2003, the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (K/DOQI) published a guideline recommending tight control of serum calcium, phosphorus, calcium-phosphorus product (Ca x P), and intact parathyroid hormone levels in patients with chronic kidney disease. Within the context of this guideline, we explored associations of these plasma concentrations with all-cause mortality risk in incident dialysis patients in The Netherlands.

METHODS

In a large, prospective, multicenter, cohort study (Netherlands Cooperative Study on the Adequacy of Dialysis), we included 1,629 patients new on hemodialysis or peritoneal dialysis therapy between 1997 and 2004. Multivariate Cox regression models containing calcium level, phosphorus level, intact parathyroid hormone level, age, comorbidity, primary kidney disease, nutritional status, albumin level, dialysis dose, and hemoglobin level were used to examine mortality risks.

RESULTS

Mean age was 60 +/- 15 (SD) years, 61% were men, and 64% were treated with hemodialysis. In adjusted time-dependent survival analysis, all-cause mortality risk increased in hemodialysis patients by 40% (hazard ratio [HR], 1.4; 95% confidence interval [CI], 1.1 to 1.7) and in peritoneal dialysis patients by 60% (HR, 1.6; 95% CI, 1.1 to 2.4) for plasma phosphorus levels greater than the target. In addition, having elevated plasma Ca x P product levels increased mortality risk by 40% (HR, 1.4; 95% CI, 1.1 to 1.8) in hemodialysis patients and 50% in peritoneal dialysis patients (HR, 1.5; 95% CI, 1.0 to 2.2). In both patient groups, no significant effects were observed for plasma levels less than the targets.

CONCLUSION

In time-dependent survival analysis, the presence of plasma phosphorus and Ca x P product concentrations greater than K/DOQI targets increased all-cause mortality risk in hemodialysis and peritoneal dialysis patients.

Hyperparathyroidism secondary to hypovitaminosis D in hypoalbuminemic is less intense than in normoalbuminemic patients: a prevalence study in medical inpatients in southern Brazil

Hypovitaminosis D has been reported in tropical countries, but this hormone has seldom been studied in Brazil. Our purpose was to study the prevalence of hypovitaminosis D in patients hospitalized in internal medicine wards in Southern Brazil. Possible associated factors were studied. We studied 81 adult patients in early spring. Mean serum 25(OH)D was 12 +/- 8.57 ng/mL; hypovitaminosis D was severe (< 10 ng/mL) in 27 (33.3%) patients, and moderate (> or = 10 ng/mL and < 20 ng/mL) in 36 (44.5%) patients. Clinical evaluation did not yield any data associated with hypovitaminosis D. Serum 25(OH)D levels of up to 20 ng/mL were associated with decreased mean serum total calcium (p = 0.001), ionized calcium (p = 0.01), and phosphorus (p = 0.044) levels, and increased mean serum PTH level (p = 0.001). In a multiple regression model, serum PTH level was independently affected by serum total calcium (p = 0.01), phosphorus (p = 0.009), and albumin (p = 0.009) levels. Hypovitaminosis D patients had lower mean serum albumin levels (p = 0.004), and serum 25(OH)D levels were directly correlated to serum albumin levels (p < 0.0001). Albumin influenced independently PTH response to hypovitaminosis D; normoalbuminemic hypovitaminosis D patients had higher mean serum PTH than hypoalbuminemic patients.

CONCLUSION

Hypovitaminosis D prevalence was very high in medical inpatients in Southern Brazil, in early spring. Nevertheless, secondary hyperparathyroidism was less intense in hypoalbuminemic hypovitaminosis D patients suggesting that in these patients free serum 25(OH)D was closer to normal.