Cutaneous oxalate deposition in a hemodialysis patient

Vitamin B6 and oxalic acid in clinical nephrology

OBJECTIVE

Vitamin B(6) (VB(6)) is a water-soluble vitamin, which is important for the normal functioning of multiple organ systems. It is metabolized to the active molecule pyridoxal-5-phosphate (PLP). Oxalic acid (OA) is thought to be a uremic toxin that participates in the pathogenesis of the uremic syndrome. The objectives of this study were as follows: (1) to evaluate the plasma and erythrocyte VB(6) (effect of PLP; effect of PLP was in indirect relationship with the concentration of erythrocyte VB(6)), and plasma and urinary OA in marathon runners, in patients with acute intermittent porphyria (AIP) and variegate porphyria, and in patients with stage 1 chronic kidney disease (CKD), chronic glomerulonephritis and nephrotic syndrome (CGNS); (2) to examine the influence of water diuresis in healthy subjects, and the influence of sodium diuresis (high sodium intake) and an intravenous administration of furosemide on the urinary excretion of VB(6) and OA in CKD stage 3-4 patients; and (3) to evaluate the influence of erythropoietin treatment on erythrocyte VB(6) (effect of PLP) in hemodialysis (HD) patients, and the influence of continuous ambulatory peritoneal dialysis (CAPD) therapy on plasma VB(6) and OA and their peritoneal clearance and transfer.

DESIGN AND SETTING

This study was conducted at the Nephrological Clinic of L. Pasteur Faculty Hospital and of Medical School of P. J. Safarik University. A combination of 29 marathon runners, 15 patients with CG and NS, 11 patients with AIP, 1 patient with variegate porphyria, 15 healthy subjects, 27 CKD stage 3-4 patients, 30 HD, and 27 CAPD patients were used in the study.

RESULTS

After a marathon run, plasma and erythrocyte VB(6) significantly decreased and plasma OA increased. Plasma (15.5 +/- 3.8 nmol/L) and erythrocyte VB(6) (effect of PLP: 42.1% +/- 7.5%) were decreased and plasma OA (9.8 +/- 2.3 micromol/L) was significantly elevated in patients with CGNS and stage 1 CKD. In patients with AIP, deficiency of plasma (24.3 +/- 5.2 nmol/L) and erythrocyte VB(6) (effect of PLP: 46.2% +/- 7.0%) and hyperoxalemia (9.39 +/- 2.5 micromol/L) were present. The urinary excretion of VB(6) and of OA during maximal water diuresis and after intravenous administration of furosemide increased significantly (P < .01), but was not affected by the high intake of NaCl (P > .05). Erythropoietin treatment in HD patients led to the erythrocyte VB(6) deficiency. This finding is an indirect evidence that erythrocyte VB(6) is consumed by the hemoglobin synthesis much more during EPO treatment. In CAPD patients, plasma value of VB(6) (127.3 +/- 66.9 micromol/L) was in the normal range and plasma OA (23.6 +/- 7.4 micromol/L) was significantly elevated. Mean value of peritoneal clearance of VB(6) was 8.8% and of OA was 76.9% of urea clearance.

CONCLUSION

Our study indicates that deficiency of VB(6) led to hyperoxalemia and hyperoxaluria in patients with CKD. Deficiency of VB(6) in CKD stage 4-5 patients potentiates the uremic hyperoxalemia and hyperoxaluria.

AA amyloidosis due to chronic oxalate arthritis and vasculitis in a patient with secondary oxalosis after jejunoileal bypass surgery

We report a case of a woman with secondary oxalosis after jejunoileal bypass surgery for obesity, who presented with oxalate stone disease and renal insufficiency requiring dialysis. Thirty years after surgery, longstanding osteoarticular symptoms were recognized as oxalate arthritis. Eventually, she also developed oxalate vasculitis, which improved with corticoid treatment and intensification of dialysis. Work-up for kidney transplantation revealed AA amyloidosis on gastric and colonic biopsies. Since no other cause of chronic inflammation could be identified, it was concluded that the amyloidosis was secondary to oxalate arthritis and vasculitis. To our knowledge, this is the first report on this association.

Oxalic Acid as a uremic toxin

OBJECTIVE

Oxalic acid (OA) is thought to be a uremic toxin that participates in the pathogenesis of uremic syndrome. The objectives of this study were to: (1) evaluate the plasma levels of OA in patients with chronic renal disease with various levels of glomerular filtration rate and after renal transplantation; (2) investigate the salivary secretion of OA and ascorbic acid in healthy subjects and in patients with chronic renal failure (CRF); (3) examine the influence of water and sodium diuresis and furosemide administration on the urinary excretion of OA and ascorbic acid in healthy subjects and in CRF patients without dialysis treatment; and (4) evaluate the influence of renal replacement therapy (RRT) on secondary hyperoxalemia in hemodialysis patients.

DESIGN AND SETTING

This study was conducted at the Nephrological Department of P.J. Safárik University. Sixty-one patients with chronic renal disease, 64 CRF patients, 32 continuous ambulatory peritoneal dialysis (CAPD) patients, 15 hemodialysis patients, 21 patients after renal transplantation, and 15 healthy subjects were examined. Maximal water diuresis, diets with low (2 g/day) and high (15 g/day) sodium intake, administration of intravenous furosemide (20 mg), and renal replacement therapy (CAPD, hemodialysis, hemofiltration, and postdilution hemodiafiltration) were utilized in the study.

RESULTS

In patients with chronic renal disease and those after renal transplantation, direct relationships between plasma OA and serum creatinine were found (r = 0.904 and 0.9431, respectively, P < .01). Despite a high level of plasma OA in uremic patients (23.1 +/- 10 micromol/L), there was no significant difference in salivary OA between control subjects (128 +/- 19 micromol/L) and CRF patients (135 +/- 24 micromol/L). The urinary excretion of OA during maximal water diuresis (from 37.5 to 110.3 micromol/4 hours) and after intravenous furosemide (from 34.5 to 66.7 micromol/3 hours) increased significantly, but was not affected by high intake of NaCl. The most significant decrease of plasma OA was observed during postdilution hemodiafiltration (63.3%).

CONCLUSION

Our study indicates that renal replacement therapy is not effective for a permanent reduction of elevated plasma levels of OA.

Calcium oxalate saturation in dialysis patients with and without primary hyperoxaluria

Calcium oxalate supersaturation of the blood is associated with deposition of crystals in various tissues. We measured the serum levels of oxalate, citrate, calcium, and magnesium to estimate their saturation in 112 hemodialysis patients without primary hyperoxaluria and two boys with primary hyperoxaluria. Serum levels of oxalate and citrate were determined by high-performance capillary electrophoresis, while calcium and magnesium were measured by ICP spectroscopy. The serum levels of oxalate, citrate, calcium, and magnesium were 44.9+/-16.5, 138.1+/-54.9 micromol/l, 2.30+/-0.28, and 1.07+/-0.18 mmol/l, respectively, while the levels in patients with primary hyperoxaluria were 83.9+/-34.3, 197.9+/-63.5 micromol/l, 2.53+/-0.15, and 1.14+/-0.34 mmol/l, respectively. Serum calcium oxalate saturation (SS), as calculated by the Equil program, was significantly correlated with the serum oxalate level. Most patients showed metastable supersaturation (1<SS<8.9), which was associated with a serum oxalate level of more than 30 micromol/l. Serum saturation exceeded the formation product (SS=8.9) in some specimens from patients with type 1 primary hyperoxaluria. The serum calcium oxalate saturation [SS(CaOx)] showed a significant positive correlation with the levels of oxalate [Ox], calcium [Ca], and citrate [Cit]: [SS(CaOx)]=-0.3562+34.634[Ox]+0.394[Ca]-0.483[Mg]+0.101[Cit], (all mmol/l, r=0.9848, P<0.01). This formula is useful for estimating the saturation. In conclusion, the serum oxalate level is a good indicator of calcium oxalate saturation and should be monitored accurately while keeping it lower in dialysis patients.

Cutaneous ectopic breast calcification in a haemodialysis patient

This case report details the unique breast calcification and swellings of a 61-year-old lady. The ectopic breast calcification was a result of chronic renal failure and hyperparathyroidism secondary to vesiculo-ureteric reflux nephropathy. Subcutaneous nodules were also noted around her ileostomy (from surgery due to Crohn's disease) and abdominal wall. Mammogram revealed calcified breast discs and lobules with extensive vascular calcification. Histological biopsies revealed extensive calcium deposition (benign). Cutaneous deposition of calcium oxalate has been described in 13 patients world wide, usually involving fingers, ears, or nose. Two of these report breast involvement, but this is described as less extensive and more focal calcification on clinical findings and mammography. This case report describes a rare condition with extraordinary mammographic images.

Cutaneous deposition diseases. Part II

Part II of the cutaneous deposition disorders focuses on cutaneous calcification and ossification, alkaptonuria and ochronosis, and gout. These disorders have in common the deposition of materials in the dermis or subcutis and often involve metabolic defects in hormonal and enzymatic regulation. The pathogenesis, clinical findings, and treatment of these diseases are discussed. Both the histologic and ultrastructural findings are reviewed.

Bladder calcifications after photodynamic therapy: analysis of a rare complication

OBJECTIVES

We analyzed bladder calcifications occurring after photodynamic therapy administered for the treatment of superficial bladder cancer, a finding not previously reported after this treatment.

METHODS

Bladder biopsies from 20 patients undergoing photodynamic therapy were evaluated. Bladder calcifications were identified in 2 patients and analyzed for composition.

RESULTS

One patient had diffuse microcrystalline deposition in two biopsies composed of calcium oxalate monohydrate A. A second patient had a focal stone at a healing biopsy site composed of monoclinic calcium hydrogen phosphate dihydrate (brushite) (66%), calcium oxalate (25%), hydroxyapatite (6%), and protein (3%).

CONCLUSIONS

Rare calcium oxalate and brushite calcifications were identified after photodynamic therapy and presumed to occur because of tissue injury associated with treatment.