[A case of hypercalcemia in hemodialysis]. / Un caso di ipercalcemia in emodialisi.

We report a case of hypercalcemia in a female patient who was restarted on hemodialysis 22 years after renal transplantation. Graft biopsy showed chronic post-transplant nephropathy. Treatment with immunosuppressants and steroids was maintained owing to residual graft function. She was then given oral paracalcitol 1 µg/d for secondary hyperparathyroidism (iPTH 850 pg/mL) and her transplant medication was reduced and then discontinued. After this, the patient referred widespread joint pain, especially in the hips and subsequently presented with erythema nodosum. She also developed hypercalcemia and hyperphosphatemia which persisted after stopping paracalcitol. The clinical picture of increased serum calcitriol, with depressed PTH, suggested sarcoidosis, despite normal ACE levels, a chest X-ray and skin biopsy confirmed the diagnosis, and the patient was started on prednisone 50 mg/day, resulting in prompt normalization of both symptoms and blood chemistry. This is a rare case of hypercalcemia secondary to sarcoidosis in an uremic patient. The sarcoidosis was most likely suppressed by the transplant therapy and rapidly developed after this was suspended. Prompt diagnosis resulted in a good therapeutic response.

[Selective vitamin D receptor activation: effect on renal physiopathology]. / L'attivazione selettiva dei VDR: impatto sulla fisiopatologia renale.

The wide distribution of the vitamin D receptor (VDR) suggests that its activators (VDRAs) are involved in diverse organ functions including the cardiovascular, immune, and reproductive systems. These actions are likely to be independent of PTH and calcium/phosphorus levels. Earlier studies had shown that calcitriol was able to favorably influence experimental nephritis, remnant kidney glomerulosclerosis, and interstitial fibrosis, mediated through inhibition of inflammatory cytokines. Recently, VDRAs were shown to inhibit the reninangiotensin system (RAS), acting directly on the renin gene promoter. This action is independent of the systemic RAS blockade. VDRAs also inhibit other important gene promoters including NF-kB and p65, which are known to foster inflammation and fibrogenesis. These multiple actions result in a decrease in macrophage infiltration, fibroblast activation, and endothelial mesenchymal transition in the kidney. These findings represent the rationale for the use of VDRAs, in association with RAS blocking agents, to counteract the progression of renal injury characterized by inflammation and neofibrogenesis. However, despite promising preliminary results, the human studies available to date do not allow to draw definitive conclusions on this matter.

Effects of potassium citrate supplementation on bone metabolism.

Western diets rich in animal protein result in long-term acid loading that, despite corresponding increases in net renal acid excretion, may induce a chronic state of acidemia. This may have deleterious effects on both the kidney and bone, by increasing the risk of calcium stone in the former and leading to chemical dissolution of mineral alkaline salts in the latter. Whereas supplementation with alkaline citrate has been shown to reduce stone recurrences, its effect on bone turnover has received less attention. The aim of the present study was to evaluate whether potassium citrate favorably affects bone turnover markers in postmenopausal females with low bone density. Thirty women, aged 58 +/- 8.1 years, were enrolled and studied on basal conditions and after a 3-month course of potassium citrate supplementation (0.08-0.1 g/kg b.w. daily). Twenty-two women concluded the study while 8 withdrew. Twenty-four age-matched healthy women were taken as control cases. All were evaluated for electrolyte and acid-base balance-related parameters, bone turnover, markers and renal function. A significant decrease in net acid excretion was observed upon citrate supplementation, and this was paralleled by a significant decrease of urinary deoxypyridinolines, hydroxyproline-to-creatinine ratios, and, to a lesser extent, serum osteocalcin. Percent variations of urine citrate were inversely related to those of deoxypyridinolines and hydroxyproline. No change in these chemistries occurred in the control group. Our results suggest that treatment with an alkaline salt, such as potassium citrate, can reduce bone resorption thereby contrasting the potential adverse effects caused by chronic acidemia of protein-rich diets.

[Intact whole bioactive parathormone: problems arising from comparing different methods]. / Paratormone intatto intero bioattivo: le problematiche emergenti dal confronto.

BACKGROUND: Parathyroid hormone (PTH) has important applications in the nephrological clinical practice. Because assays of Intact PTH (I-PTH) are liable to interferences by N-truncated fragments, a novel method for whole-(1-84) PTH has been proposed. This study is aimed at comparing the latter with some of the previous I-PTH assays. For each method the results are referred to pertinent markers of mineral metabolism. METHODS: We enrolled 171 subjects, including 56 healthy controls (C), 65 calcium stone- formers (CaSF), 40 haemodialysis patients (HD), 10 with primary hyperparathyroidism (PHP). On blood samples we measured: I-PTH by four methods (N-Tact, Advantage, Elecsys, Scantibodies), whole-(1-84) PTH, defined as CAP (Cyclase Activating PTH), total and ionised calcium, phosphate, vitamin D, osteocalcin and Crosslaps. The difference between I-PTH and CAP Scantibodies is defined as CIP (Cyclase Inhibiting PTH). RESULTS: Despite relating to each other (r>0.97) PTH values varied remarkably among methods. For all methods, the reference intervals differed from those provided by the producer. Assuming these new ranges, 10 CaSF had over-range values not always associated with abnormalities of mineral metabolism. One of the PHP patients was normal for I-PTH with 2/4 methods. In HD the differences among methods were even greater, there were inverse (p<0.05) and direct (p<0.001) relationships with ionised calcium and osteocalcin-crosslaps, respectively. The CAP/CIP ratio was lower in low bone turnover patients, but the two subgroups widely overlapped. CONCLUSIONS: This study indicates that the reliability of I-PTH assays is still unsatisfactory, and none of the four methods emerged as the best. Assay for CAP only improves diagnostic efficiency, whereas the CAP/CIP ratio does not exhibit powerful discriminating capacity. Our suggestion is that each Centre should establish its own reference ranges. PTH assay should always be coupled with measurements of other markers of mineral metabolism as well as renal function.

Steroid and cyclophosphamide in IgA nephropathy.

BACKGROUND: IgA nephropathy is associated with a wide spectrum of possible lesions. Therefore, different responses to anti-inflammatory or immunosuppressive therapies should be expected with acute inflammatory changes, which are predominantly reversible, and with prevalently sclerotic lesions. METHODS: The effects of a combined schedule of prednisone and cyclophosphamide was analysed in the specific subset of IgA nephropathy patients with acute inflammatory histologic changes associated with haematuria and proteinuria. Two groups of patients, with similar histologic lesions and clinical presentation, were considered. The first group (12 patients) was treated within 1 week after renal biopsy; starting with three pulses of methylprednisolone (1 g) followed by oral prednisone (0.8 mg/kg body weight for 2 weeks, 0.6 mg/kg for another 2 weeks, 0.4 mg/kg for an additional 4 weeks, then slowly tapered by 5 mg each month until discontinuation) and 1.5 mg/kg cyclophosphamide for 2 months. A second sample of eight untreated patients served as a control group. Treated and untreated patients had diffuse mesangial proliferation with florid crescents (8-60% in treated and 10-40% in untreated patients) with mild degree of glomerular sclerosis and interstitial changes. Basal creatinine (167 micromol/l, range 79-371 vs 132 micromol/l, range 79-256) and proteinuria (3.0 g/24 h, 1.0-4.9 vs 3.3 g/24 h, 1.0-13.7) were not statistically different between treated and untreated patients respectively. Nine treated and six untreated patients were hypertensive. Blood pressure treatment did not include ACE-inhibitors. RESULTS: Untreated patients' 5-year renal survival, as assessed by the Kaplan-Meier method, was found to be significantly lower than treated patients (37.5 vs 91.6%, log-rank P=0.01 and Breslow test P=0.008; relative risk to reach the endpoint of a 100% increase in serum creatinine=3.58, P=0.03). CONCLUSION: This short course of therapy with prednisone and cyclophosphamide has been effective in a subset of IgA nephropathy patients with florid glomerular changes and major urinary abnormalities, turning off phlogistic activity and preventing subsequent progression toward renal failure.

Angiotensin I-converting enzyme genotype significantly affects progression of IgA glomerulonephritis in an italian population.

To evaluate the role of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in the progression of immunoglobulin A glomerulonephritis (IgA-GN), genotype distribution in 81 biopsy-proven cases of IgA-GN was studied. A logistic regression model showed that the risk for homozygous DD was not significantly elevated in patients with IgA-GN compared with healthy subjects (odds ratio = 1.16; confidence interval [CI], 0.4 to 3.3). However, the 5-year (78% v 90%) and 10-year (52% v 82%) renal survival rates for 47 patients with serum creatine (Cr) levels of 1.5 mg/dL or less at biopsy was significantly less in DD patients (n = 18; chi2 = 5.41; P = 0.02). The hazard ratio (HR) for DD (multivariate analysis from Cox proportional model after adjustment for known factors of progression, such as hypertension [HPT] and proteinuria [PTO]) was 3.07 (CI, 1.1 to 9.4). The HR for heavy PTO was 6.1 (CI, 1.9 to 19). The association of DD genotype with progression was even more striking when patients with other risk factors (heavy proteinuria) were excluded, as shown by DD-related risk in the absence (HR = 3.6; CI, 1.1 to 12) and presence (HR = 2; CI, 0.4 to 10) of PTO. The risk ratio was further increased by the coexistence of DD + PTO (HR = 9.16; CI, 1.8 to 15.7). Furthermore, in a cross-sectional study among patients with IgA-GN, a logistic regression model showed that the risk for homozygous DD was greater, although not at a statistically significant level in the end-stage renal failure subgroup compared with the normal renal function subgroup (odds ratio = 3.16; CI, 0.7 to 13.7) after adjustment by sex, age at biopsy, HPT, PTO, and therapy. Last, DD was significantly more frequent in those patients who started hemodialysis at an earlier age (chi2 for trend = 6.81; P = 0.009). Our study further supports that ACE genotype is a risk factor not for the development, but for the worsening of IgA-GN clinical course. However, on the basis of current knowledge, we cannot exclude that I/D polymorphism may simply serve as a prognostic marker, eventually linked with other discrete loci involved in the progression of renal damage.