Prevalence of hypercalcitoninemia in patients on maintenance dialysis referred to kidney transplantation.

AIMS: Elevated calcitonin concentrations in dialysis patients had led to thyroidectomy for a benign C-cell hyperplasia in dozens of patients in the past decade. The prevalence of hypercalcitoninemia, however, has not been examined in a large cohort of dialysis patients. METHODS: We, therefore, measured calcitonin concentrations in 283 dialysis patients. We used different reference intervals: according to the threshold to perform further stimulation tests (i.e. > 10 pg/ml) and new reference intervals for the currently used assay (i.e. serum calcitonin concentration < 11.5 pg/ml in men and < 4.6 pg/ml in women). RESULTS: Median calcitonin concentrations of men and women were 12 (1; 290) pg/ml vs 2 pg/ml (1; 45), respectively, (p < 0.0001). The prevalence of hypercalcitoninemia was 10% in women and 58% in men using a cut-off of 10 pg/ml. Applying the new reference intervals 31% of women and 54% of men presented with hypercalcitoninemia. All patients with basal calcitonin concentrations above 50 pg/ml were men (highest calcitonin concentration was 290 pg/ml). Two of them underwent thyroidectomy and had C-cell hyperplasia. CONCLUSION: The prevalence of hypercalcitoninemia in dialysis patients amounts to 46%. It is more common in male than in female dialysis patients.

Calcitonin concentrations in patients with chronic kidney disease and medullary thyroid carcinoma or c-cell hyperplasia.

It is currently not known which level of pentagastrin-stimulated calcitonin serum concentration indicates medullary thyroid carcinoma in patients with chronic kidney disease (CKD). We examined CKD stage 3-5 patients who had total thyroidectomy because of a pentagastrin-stimulated calcitonin concentration greater than 100 pg/ml, and tested the diagnostic performance of basal and pentagastrin-stimulated calcitonin levels for differentiating medullary thyroid carcinoma and C-cell hyperplasia in this patient population. A total of 180 CKD patients presented with an elevated calcitonin level and had a pentagastrin stimulation test. Forty patients showed a maximum pentagastrin-stimulated calcitonin concentration greater than 100 pg/ml, and 22 patients had a total thyroidectomy. Seven of these 22 patients presented with a medullary thyroid carcinoma, all other patients showed C-cell hyperplasia. Patients with medullary thyroid carcinoma showed higher unstimulated (212 pg/ml (36-577) vs 42 pg/ml (17-150); P < 0.001) and higher maximum pentagastrin-stimulated calcitonin concentrations (862 pg/ml (431-2423) vs 141 pg/ml (102-471); P < 0.001) as compared to patients with C-cell hyperplasia. The sensitivity (100%) and specificity (93%) estimates suggested that a maximum pentagastrin-stimulated calcitonin concentration greater than 400 pg/ml indicates the presence of medullary thyroid carcinoma in patients with CKD. Receiver-operating characteristic (ROC) analysis revealed an area under the ROC plot of 0.99 for maximum pentagastrin-stimulated calcitonin concentrations. A maximum pentagastrin-stimulated calcitonin concentration greater than 400 pg/ml appears to be a clinically meaningful threshold for thyroidectomy.

Renal function and glomerular permselectivity late after living related donor transplantation.

Living related kidney transplantation is the preferable procedure for renal replacement therapy. The aim of the current study was to determine systemic hemodynamic and intrarenal adaptions in donors and recipients late after living related kidney transplantation. Furthermore, glomerular permselectivity was assessed in these subjects. We studied mean blood pressure (MAP), glomerular filtration rate (GFR), renal plasma flow (RPF), microalbuminuria (MIA), 24-hr urinary protein excretion, and glomerular permselectivity (fractional clearance of neutral dextrans [thetaD] as a marker for size selectivity and fractional clearance of dextran sulfate [thetaDS] to assess charge selectivity) in 22 donors and 22 recipients. MAP was normal in the donor group (102 +/- 4 mmHg), but five patients had blood pressure above 140/90 mmHg. This 18%, however, is lower than the prevalence of hypertension in the age-adjusted general population in Austria. The recipients also had normal MAP at the time of study (99 +/- 3); however, 13 needed antihypertensive therapy. GFR and RPF were lower in recipients than in donors (53 +/- 8 vs. 72 +/- 11 and 314 +/- 74 vs. 412 +/- 86 ml/min respectively). In the donor group, GFR was 137 +/- 45% of the expected age-adjusted mean value/kidney due to hyperfiltration. Proteinuria and MIA were higher in the recipients than in the donors (0.39 +/- 0.22 vs. 0.07 +/- 0.04 g/day, 137 +/- 136 vs. 26 +/- 15 mg/day). Nonetheless, five donors had an elevated MIA. A higher need for antihypertensive medication could be observed in recipients with previous rejection episodes, as well as a significantly higher urinary protein excretion and MIA (0.7 +/- 0.42 vs. 0.24 +/- 0.14 g/day, 336 +/- 380 vs. 48 +/- 32 mg/day). ThetaDS was significantly higher in the recipients, whereas thetaDS of the donors was identical to the value obtained from 18 healthy controls (0.7 +/- 0.08 vs. 0.6 +/- 0.06). OD was similar in all groups studied. In conclusion, 76 months after uninephrectomy for renal donation, mild changes in glomerular permselectivity occurred in a subset of donors without affecting renal excretory function. In recipients, proteinuria was due to a defect in glomerular charge selectivity.