Deficiency and urinary losses of factor XII in adult nephrotic syndrome

Acquired factor XI deficiency in a child with membranoproliferative glomerulonephritis

We describe a 7-year-old male with membranoproliferative glomerulonephritis who presented with nephrotic syndrome and subsequently developed factor XI (fXI) deficiency. An association between these conditions has not been described previously. In this case, fXI deficiency was caused by an antibody to fXI that enhanced clearance of the protein from plasma. Loss of fXI in the urine did not appear to be involved. Antibody-mediated clearance of prothrombin or factor X can cause acquired deficiencies of these proteins. This is the first report, to our knowledge, of an antibody that causes fXI deficiency by this mechanism.

Transient Ischemic Attack and Nephrotic Syndrome: Case Report and Review of Literature

Thrombotic complications in patients with nephrotic syndrome are attributed to a hypercoagulable state. Venous thrombosis is common, but arterial thrombosis occurs less frequently in adult nephrotic patients. We report a case of recurrent transient ischemic attacks as an initial manifestation of nephrotic syndrome due to early-stage membranous glomerulonephritis, review the literature for similar cases, and briefly discuss this potentially life-threatening condition. We observed that transient ischemic attack or ischemic stroke could be the initial manifestation of nephrotic syndrome. Our observation may serve as reminder to consider nephrotic syndrome as a possible contributor when evaluating patients with transient ischemic attacks with no other discernable clues. A high index of suspicion alone avoids the unnecessary withholding of prophylaxis or treatment that can be life saving.

Thromboembolic complications in the nephrotic syndrome: Pathophysiology and clinical management

Patients with the nephrotic syndrome are at increased risk of developing venous and arterial thromboembolism, the most common of which is renal vein thrombosis. There are several unanswered or controversial issues relating to the nephrotic syndrome and thromboembolism, which include the mechanism of thromboembolism, and optimal diagnostic and anticoagulant management strategies. This review will discuss several of these issues: the epidemiology and clinical spectrum of thromboembolic disease occurring in patients with the nephrotic syndrome; the pathophysiology of the hypercoagulable state associated with the nephrotic syndrome; the diagnosis of renal vein thrombosis in the nephrotic syndrome; and the evidence for prophylactic and therapeutic anticoagulation strategies in such patients.

Upregulation of hepatic LDL receptor-related protein in nephrotic syndrome: response to statin therapy

Nephrotic syndrome (N-S) is associated with elevated plasma concentration and impaired clearance of VLDL, chylomicrons (CM), and their atherogenic remnants. These abnormalities are largely due to lipoprotein lipase, hepatic triglyceride lipase, and VLDL receptor deficiencies and impaired HDL-mediated shuttling of apoE and apoC between the nascent and remnant VLDL and CM. LRP is a multifaceted endocytic receptor that is heavily expressed in the liver. LRP recognizes at least 30 different ligands including VLDL and CM remnants. These observations prompted the present study to discern the effect of N-S on hepatic LRP gene and protein expressions. The study further sought to explore the effect of lipid-lowering therapy on LRP expression in N-S. Sprague-Dawley rats were randomized to the N-S (given ip injections of puromycin aminonucleoside; 130 mg/kg on day 1, 60 mg/kg on day 14) and placebo-injected control groups. On day 14, animals were subdivided into statin-treated (rosuvastatin; 20 mg x kg(-1) x day(-1) mixed with powdered chow) and untreated groups and studied on day 28. The untreated N-S group exhibited severe proteinuria, hypoalbuminemia, hypercholesterolemia, hypertriglyceridemia, and marked elevation of hepatic tissue LRP mRNA and protein abundance. Statin administration for 2 wk resulted in significant improvements of plasma lipid profile, proteinuria, and hypoalbuminemia as well as hepatic LRP mRNA and protein abundance. In contrast, statin administration had no significant effect on either plasma lipids or hepatic LRP levels in the normal control rats. In conclusion, N-S results in marked upregulation of hepatic LRP expression that is partly reversed with statin administration. These findings exclude depressed hepatic LRP expression as the primary cause of elevated plasma lipoprotein remnants in N-S.

Erythropoietin and transferrin metabolism in nephrotic syndrome

Nephrotic syndrome is characterized by marked urinary excretion of albumin and other intermediate-size plasma proteins. This results in a profound alteration of the metabolism of many plasma proteins and protein-bound substances, as well as certain cellular and tissue proteins. This review summarizes available data on the effect of nephrotic syndrome on the metabolism and regulation of erythropoietin (EPO) and transferrin, which are essential for erythropoiesis. Studies of humans and animals have documented significant urinary losses of both EPO and transferrin in nephrotic syndrome. Urinary losses of EPO have been shown to cause EPO-deficiency anemia and prevent the normal increase in plasma EPO level in response to anemia and hypoxia in nephrotic syndrome. Similarly, transferrinuria and increased transferrin catabolism have been shown to cause hypotransferrinemia and, in some cases, iron-deficiency anemia. In addition, dissociation of iron from filtered transferrin, occasioned by a reduction in tubular fluid pH, can promote tubulointerstitial injury through the iron-catalyzed generation of oxygen free radicals. This can account in part for the role of proteinuria as a risk factor for the progression of renal disease. Subcutaneous administration of recombinant EPO has been successfully used in the management of EPO-deficiency anemia in nephrotic syndrome. Similarly, iron supplementation and nutritional support are indicated in nephrotic patients with severe transferrinuria and iron-deficiency anemia. However, correction or amelioration of the underlying proteinuria, when possible, is the ideal approach to reversal of these complications.

Acquired lecithin-cholesterol acyltransferase deficiency in nephrotic syndrome

Lecithin-cholesterol acetyltransferase (LCAT) is involved in the synthesis of plasma cholesteryl esters and is pivotal in the maturation of plasma high-density lipoprotein (HDL) and conversion of HDL3 to HDL2. In nephrotic syndrome (NS), the ratio of HDL2 to HDL3 is low even though the total concentration of HDL is generally normal. We hypothesize that the reduced HDL2/HDL3 ratio in NS is due to urinary losses of LCAT, leading to plasma LCAT deficiency. To test this hypothesis, Sprague-Dawley rats were randomized to NS (given 130 mg puromycin aminonucleoside on day 1 and 60 mg ip on day 14) or control groups and were studied on day 30. To dissect the effect of proteinuria from hypoalbuminemia, a group of Nagase rats with inherited hypoalbuminemia was included. Hepatic LCAT and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA abundance and plasma and urine LCAT activity were measured. The NS group showed a fourfold rise in serum cholesterol and triglycerides, a fivefold rise in free cholesterol, and a fourfold fall in the HDL-to-total cholesterol ratio. Despite severe hypoalbuminemia, the Nagase rats showed only a mild elevation of serum cholesterol and triglycerides with a normal serum free cholesterol and HDL-to-total cholesterol ratio. The NS group exhibited a normal hepatic LCAT-to-GAPDH mRNA ratio, a marked reduction in plasma LCAT activity, and a significant increase in urinary LCAT excretion. LCAT/GAPDH mRNA and plasma and urine LCAT were normal in Nagase rats. Thus NS led to heavy urinary losses and reduced plasma concentration of LCAT, despite normal hepatic LCAT mRNA abundance. However, hypoalbuminemia, per se, without proteinuria as seen in the Nagase rats had no effect on plasma LCAT or the HDL-to-total cholesterol ratio. Therefore, proteinuria, not hypoalbuminemia, causes LCAT deficiency and a depressed HDL-to-total cholesterol ratio in NS.

Acquired protein S and antithrombin III deficiency caused by nephrotic syndrome: an unusual cause of graft thrombosis

Thrombotic phenomena are well-recognized complications of nephrotic syndrome attributable to loss of intermediate-sized antithrombotic proteins in the urine, resulting in a hypercoaguable state. As such, nephrotic syndrome may be associated with a reduction in circulating antithrombin III and free protein S levels. Associated spontaneous thrombotic complications are generally venous in nature, with arterial thrombosis occurring less frequently. Hypercoagulability caused by acquired nephrotic syndrome has not generally been recognized as a cause of acute thrombosis of arterial bypass grafts. We report two patients who after having nephrotic syndrome sustained acute thrombosis of their arterial bypass grafts. Pathogenesis and management are discussed.

Arterial thrombosis in the nephrotic syndrome

Thrombosis is a frequent cause of morbidity and mortality in patients with the nephrotic syndrome. Venous thrombotic complications are well recognized but arterial complications are rare. Thrombosis is multifactorial, and has been attributed to a hypercoaguable state due to alterations in blood levels of the various factors involved in the coagulation and fibrinolytic systems, alterations in platelet function, venous stasis, haemoconcentration, increased blood viscosity and possibly the administration of steroids. Thrombosis in general and arterial thrombosis in particular is a significant and potentially serious problem in nephrotic patients. Awareness of the condition and its pathogenesis is needed. Assessment for the risk factors is required to allow appropriate prophylactic measures to be taken.

Plasma concentration and urinary excretion of erythropoietin in adult nephrotic syndrome

PURPOSE

Nephrotic syndrome (NS) is associated with a significant alteration of protein metabolism. While lowering the plasma concentrations of certain proteins, the disease often raises the level of certain other proteins. The current study was undertaken to determine the effect of NS on erythropoietin (EPO) metabolism.

PATIENTS AND METHODS

We measured the EPO concentration in plasma and urine of 26 patients with NS by an immunologic assay using a rabbit antiserum against recombinant human EPO. The results were compared with those obtained in a group of 12 normal control subjects.

RESULTS

Despite a significant reduction in the hemoglobin concentration in the NS group compared with the control group (125 +/- 25 g/L versus 148 +/- 11 g/L, p less than 0.05), the plasma EPO concentration in the NS group was not significantly different from that seen in the control group (6.2 +/- 4.5 mU/mL versus 6.7 +/- 2.4 mU/mL, p = NS). No significant correlations were found between plasma EPO and hemoglobin concentration, serum creatinine, serum albumin, or urinary albumin excretion rate. Moreover, comparison of the NS patients with serum creatinine concentrations less than or equal to 1.5 mg/dL (133 mumol/L) with those exhibiting creatinine concentrations exceeding 1.5 mg/dL did not reveal a significant difference in mean plasma EPO concentration. Significant amounts of EPO were found in the urine of the patients with NS, while none was detected in the urine of the control subjects.

CONCLUSION

We conclude that plasma EPO is inappropriately low in patients with NS. This is due, at least in part, to the urinary/renal losses of this protein and can potentially contribute to anemia in NS patients or compound the problem in those with concurrent renal insufficiency and diminished EPO production.

Do circulating factors play a role in the pathogenesis of minimal change nephrotic syndrome?

This review examines the studies which have been undertaken to test the hypothesis that minimal change nephrotic syndrome of childhood (MCNS) is a primary immune disorder and that there is altered T-cell function which results in release of a circulating factor. This factor alters glomerular permeability, perhaps by modifying charge sites in the glomerular capillary bed, and results in selective proteinuria. The abnormalities in immune function observed in MCNS are summarized, as are the studies of circulating factors which have been identified. Although some agents have been shown to alter capillary permeability, the unequivocal demonstration of such a factor causing selective proteinuria in vivo, either directly or indirectly, is lacking. The question is raised whether intrarenal release or activation of mediators of altered permeability, rather than the systemic release of such factors, may be important in the pathogenesis of MCNS.

Coagulation cascade, fibrinolytic system, antithrombin III, protein C and protein S in patients maintained on continuous ambulatory peritoneal dialysis

We studied the coagulation cascade, fibrinolytic system and naturally occurring anticoagulants in a group of 14 patients with end-stage renal disease maintained on continuous ambulatory peritoneal dialysis (CAPD). The results were compared with those obtained in a group of ten normal volunteers. Plasma procoagulant activities of factors XII, XI, IX, VIII, VII, X and II were significantly greater in the CAPD group as compared to the normal control group. Likewise plasma concentrations of total and free protein S were increased in the CAPD group. Although the mean value for plasma factor V activity in the CAPD group was higher than that found in the control group the difference did not attain statistical significance. In addition plasma fibrinogen concentration and factor VIII-related antigen level were significantly increased in CAPD patients. No significant difference was found between the CAPD patients and the control group with respect to plasma levels of protein C, antithrombin III, plasminogen or alpha 2-antiplasmin. In summary, the results demonstrate a tendency for increased levels of various coagulation factors and protein S in CAPD patients with no significant alterations in the levels of various fibrinolytic and endogenous anticoagulant agents, i.e. antithrombin III and protein C. The clinical significance and the mechanism responsible for the observed changes require further investigation.

Activation of intrinsic coagulation pathway in pre-eclampsia

Disseminated intravascular coagulation, thrombocytopenia, consumption of factors VIII and II, and antithrombin deficiency have been previously demonstrated in pre-eclampsia. However, the precise mechanism responsible for initiation of disseminated intravascular coagulation has not been elucidated. The present study documents activation of the intrinsic coagulation pathway in a patient with severe pre-eclampsia. The studies revealed marked reductions of plasma coagulant activities of all intrinsic pathway factors, i.e., XII, XI, IX, and VIII. In addition, the ratio of plasma factor XII activity to antigen concentration was markedly abnormal, and plasma high-molecular-weight kininogen concentration was diminished. It is suggested that activation of the intrinsic coagulation pathway may be operative in the genesis of disseminated intravascular coagulation in pre-eclampsia.

The contact activation system: biochemistry and interactions of these surface-mediated defense reactions

This review is intended to be a critical state-of-the-art overview of the activation and inhibition of the proteins (factor XII, prekallikrein, high molecular weight kininogen, and factor XI) of the contact phase of coagulation. Specifically, this review will reconsider the concept of the reciprocal activation of the proteases of the contact phase of coagulation, factor XII, and prekallikrein, in light of much recent evidence indicating that factor XII, itself, autoactivates when associated with negatively charged surfaces. In addition, the mechanisms for amplification of activation of the proteins of the contact phase of coagulation will be discussed from the pivotal role of high molecular weight kininogen, or one of its altered forms, serving as a cofactor to order the activation of the zymogens it is associated with. The role and relative importance of each of the naturally occurring plasma protease inhibitors (C1-inhibitor, alpha-2-macroglobulin, alpha-1-antitrypsin, antithrombin III, and alpha-1-antiplasmin) will be assessed as they relate to the dampening of contact phase activation. Finally, the contact phase of coagulation activation will be discussed not only as a plasma proteolytic mechanism, but also as it interacts with platelets.

Intrinsic coagulation pathway in end-stage renal disease associated with spinal cord injury treated with hemodialysis

Plasma procoagulant activities of factors XII, XI, IX, and VIII and plasma concentrations of factor XII antigen and high molecular weight kininogen (HMK) were determined in nine men with chronic renal failure (CRF) associated with long-standing spinal cord injury (SCI) treated with hemodialysis. The results were compared with those obtained in a group of 10 ambulatory CRF patients and 8 normal volunteers (control group). Congenitally deficient plasmas were used as the substrate for the measurement of procoagulant activities in a one-stage clotting assay. Monospecific antibodies were employed in the measurement of factor XII antigen and HMK using gradient plate immunodiffusion and rocket immunoelectrophoresis. Factor XII coagulant activity and antigen concentration were significantly increased in the SCI group. The mean values for plasma factor XI and IX activities in the SCI group were comparable with those observed in the ambulatory patients and normal control group. However, marked variations in factor XI and IX levels were noted among the SCI patients with a few instances of mild to moderate factor deficiencies and several cases of markedly elevated levels. Factor VIII activity was markedly increased, with only two of the nine patients exhibiting normal values. HMK concentration in the SCI group was comparable with values obtained for the other groups. Following dialysis, factor XII antigen concentration rose and factor XI activity fell slightly but significantly. The results indicate that the combination of CRF and long-standing SCI is associated with marked aberrations of intrinsic coagulation pathway. The underlying mechanisms and the clinical consequences of these abnormalities are not known and require further investigation.

Urinary excretion and deficiency of prothrombin in nephrotic syndrome

Plasma and urinary prothrombin concentration and plasma prothrombin activity were measured in a group of 17 patients with the nephrotic syndrome. An immunologic assay using a monospecific antibody against human prothrombin was employed in the measurement of prothrombin concentration in the plasma and urine. Prothrombin-deficient plasma was used as the substrate in the measurement of plasma prothrombin activity. A control group consisting of five normal volunteers was included for comparison. Both the activity and concentration of prothrombin were significantly lower in the nephrotic group as compared with the control group. Significant quantities of immunoreactive prothrombin were detected in the urine of the majority of nephrotic patients. This study has provided unequivocal evidence of urinary excretion and acquired deficiency of prothrombin in the nephrotic syndrome.

Effect of hemodialysis on contact group of coagulation factors, platelets, and leukocytes

Earlier reports have suggested possible activation and consumption of factor XII during hemodialysis. To investigate this possibility, a series of in vivo and in vitro experiments were conducted using different dialysis membranes and two different dialysates (acetate and bicarbonate). Factors XII and XI activities, factor XII concentration, and high-molecular-weight kininogen were measured. In addition, platelet count, white blood cell count, and hematocrit were monitored. Contrary to the previous reports, no discernible consumption of factor XII, factor XI, or high-molecular-weight kininogen was found irrespective of the type of membrane or the composition of the dialysate used. Transient leukopenia was noted with cellulosic membranes, whereas none occurred with polyacrylonitrile dialyzers. The composition of dialysate did not affect the white blood cell count during dialysis.