Are PTH serum levels predictive of coronary calcifications in haemodialysis patients?

BACKGROUND

Cardiac calcifications are a frequent occurrence in uraemic subjects and are probably connected to the increased cardiovascular mortality of haemodialysis patients. There is substantial support to the hypothesis that low levels of serum PTH in haemodialysis patients are associated with increased vascular and cardiac calcium deposits, due to decreased buffering capacity of bone in low turnover osteodystrophy. The present study has been carried out on a cohort of patients on haemodialysis, with exclusion of previously parathyroidectomized patients, with the aim to evaluate the association between PTH serum levels and coronary calcifications.

METHODS

The study has been carried out in a cohort of 197 haemodialysis patients. There were 133 males and 64 females. Twenty-two patients had diabetes mellitus. Average age was 58.6 +/- 12.9 years. Patients were divided into groups of intact PTH levels, 0-150 (A), 150-300 (B), 300-600 (C) and >600 (D) pg/ml.

RESULTS

The values of coronary scores in the PTH groups were as follows: (A) 624.7 +/- 939, (B) 866.4 +/- 1080, (C) 1202.8 +/- 1742.3 and (D) 1872.7 +/- 2961.9. The difference between coronary calcium scores was significant (P < 0.01). A general linear model identified serum calcium and dialysis age as independent factors of calcium deposits in the high PTH group.

CONCLUSIONS

No prominent association between low PTH serum levels and the severity of coronary calcium deposits in haemodialysis patients was found while increased levels of PTH, with special regard to very elevated levels, associated with more frequent hypercalcaemia and hyperphosphataemia, should be considered a major risk factor of coronary calcifications and cardiac events.

Cardiac calcifications: Fetuin-A and other risk factors in hemodialysis patients

Cardiac calcifications are a frequent finding in hemodialysis for chronic renal failure. Several factors may play a role in the intimal and medial calcification of coronary arteries such as age and some known atherogenetic factors. In addition, Fetuin-A has been proposed as a protective agent through solubilization of calcium phosphate salt. Fetuin-A is also a marker of inflammatory-nutritional state, and its changes could be an expression of this condition. The aim of this cross-sectional study is to evaluate the relative importance of risk factors of calcifications with special regard to Fetuin-A. The study was conducted with 132 hemodialysis patients. They were subjected to multislice computed tomography for evaluation of calcium deposits in the heart. In addition, the patients were sampled for evaluation of calcium-phosphate parameters, lipid profile, nutritional and inflammatory markers, and also Fetuin-A. There was a wide variability of the extent of calcium deposits expressed as Agatston score, with only 9.3% of patients without calcifications. Age, hemodialysis age, sex, calcium-phosphate parameters, and lipid profile were important risk factors, together with nutritional and inflammatory status of the patients. An inverse correlation between coronary calcium score and Fetuin-A emerged from a multiple regression analysis. However, there was no significant difference in serum Fetuin-A among different grades of calcium score. By dividing the patients in tertiles of serum Fetuin-A, an association between low levels of Fetuin-A and high calcification score was found. Fetuin-A as dependent variable was strictly linked to prealbumin serum levels. In addition, there was a clear link between cardiac calcification scores and inflammatory-nutritional markers. Serum calcium and treatment with calcitriol emerged as predictive variables of coronary score.Fetuin-A could be involved in the process of calcification both in the case of markedly low serum levels, due to decreased prevention of calcium phosphate precipitation, and also as a marker of inflammation, a well-known risk factor of atherogenesis. Treatment with intravenous calcitriol could marginally enhance cardiac calcifications, probably through its hypercalcemic effect.

Late symptomatic venous stenosis in three hemodialysis patients without previous central venous catheters

It is well known that catheters placed in the subclavian or internal jugular veins may develop stenosis in the vein in which the catheter lies. Because the arteriovenous fistula (AVF) relies on good venous outflow, patients with ipsilateral central venous stenosis are subject to the malfunctioning of AVF. Until now, no data were published on patients showing central vein stenosis (CVS) without a previous central venous catheter (CVC) or a pacemaker. In this article, we report on 3 hemodialysis patients manifesting CVS ipslateral to AVF. None of these patients previously had undergone CVC. The stenosis observed had characteristics and symptoms similar to those observed in stenoses consequent to CVC. We concluded that CVS also may occur in subclavian or axillary veins proximal to a working AVF in hemodialysis patients who have never had a CVC and in the absence of compressive phenomena.

Red blood cell membrane lipid peroxidation and resistance to erythropoietin therapy in hemodialysis patients

BACKGROUND

Chronic hemolysis, inadequate production of erythropoietin (EPO) or an impaired response of erythroid stem cells to EPO are the main factors of anemia in end-stage renal disease (ESRD) patients. Oxidative damage of red blood cell (RBC) membrane is a well-established cause of chronic hemolysis in hemodialysis (HD) patients. Administration of high-dose recombinant human EPO (rHuEPO) fails to correct anemia in 5 to 10% HD patients although all established factors of resistance to rHuEPO therapy have been previously ruled out or corrected.

PATIENTS AND METHODS

We investigated the degree of RBC membrane oxidative damage in 9 HD patients who failed to respond to maximal rHuEPO administration (more than 200 UI/Kg weekly for 4 months consecutively, group A), compared to 10 patients who showed a good response to standard rHuEPO therapy (group B) and to 10 patients who needed no treatment (group C). RBC malondialdehyde (MDA) was assumed as the index of oxidative stress in erythrocyte membrane.

RESULTS

No significant difference in erythrocyte MCV and MCHC, iron status, parathyroid function, aluminum and dialysis-related blood loss was observed between patients of group A, B and C. RBC MDA, reticulocyte count, plasma-free hemoglobin (fhb) and serum lactate dehydrogenase (LDH) were significantly higher while plasma haptoglobin was significantly lower in patients of group A compared to patients of groups B and C. Moreover, a significant inverse relationship was observed between RBC MDA and either plasma hemoglobin, RBC count and hematocrit when all patients were evaluated together.

CONCLUSION

In conclusion, increased oxidative damage of RBC membrane is often detectable in HD patients who fail to respond to rHuEPO administration even in the absence of all established factors of resistance to EPO. Peripheral response to rHuEPO may be normal in these patients and persistent anemia may be related to enhanced hemolysis due to oxidative stress. Oxidative damage itself may therefore be considered a factor of resistance to EPO.

The treatment of severe forms of myasthenia gravis

In this study we introduced and tested the clinical efficacy of a combined treatment based on the association of plasma exchange (PE) with high daily doses of prednisone in 18 patients with severe forms of myasthenia gravis (MG). A myasthenic score based on strength and resistance was evaluated in each patient in basal condition and during the treatment. The study design included 5 sessions of PE, performed within a period of 15 days, 1 session every 3 days, associated with administration of oral prednisone (1 mg/kg of body weight), which began at the same time as the first session and was continued following a daily schedule for at least three months. A significant improvement was obtained from the start of the therapy, with a reduction of the myasthenic score from 26.56 to 11.44 by day 10 and with further reduction after PE interruption. An early improvement, recorded within 24-48 hours of the beginning of the study design, was observed in 11/18. The administration of steroid therapy was never followed by a worsening of myasthenic symptoms (as reported when it is administered in the absence of concomitant PE). No recurrence of symptoms was reported after 29 months' follow-up. This type of therapeutic association was generally well tolerated and no unwanted side effects were observed. According to our results we can conclude that medium-high doses of oral prednisone in simultaneous association with PE lead to a successful control of severe forms of MG and may be considered a valid therapeutic strategy.

Plasmapheresis in severe forms of myasthenia gravis

In this study we introduce a new combination treatment of plasma exchange (PE) and high daily doses of prednisone for severe forms of myasthenia gravis (MG). The clinical efficacy of the combined therapy has been tested in 18 patients suffering from severe forms of MG. The protocol included 5 sessions of PE, performed in a range of 15 days, 1 session every 3 days, with concurrent administration of oral prednisone (1 mg/kg of body weight), starting at the first session of PE and given daily for at least 3 months. At the end of the entire cycle of PE, almost complete recovery (more than 90% of the initial clinical score) was obtained in 8 of 18 patients while an improvement between 60 and 90% of the initial score was achieved in 9 of 18 patients. An early improvement was noted 24 h after the beginning of plasmapheresis in 11 of 18 patients. No recurrence of symptoms was reported after 36 months of follow-up for 17 patients. The administration of steroid therapy was never followed by an early exacerbation of myasthenic symptoms as reported when it is administered in the absence of concomitant PE. According to our results, we can conclude that high doses of oral prednisone therapy in simultaneous association with PE lead to successful control of severe forms of MG, significantly superior to the therapeutic strategies until now adopted and reported in literature.

Renal function in patients undergoing cardiopulmonary bypass operations

We evaluate short- and long-term effects on renal functional reserve of cardiopulmonary bypass in 11 patients. A selected group (persistence of renal functional reserve before operation) of 11 adult patients undergoing cardiopulmonary bypass for aorta-coronary bypass were studied. Renal functional reserve tests were performed in all patients before the operation, at postoperative day 9, and at 6 months after operation. Basal glomerular filtration rate did not show significant changes at 9 days and at 6 months after operation. On the contrary, renal functional reserve was absent at 9 days, but it was restored to preoperative levels at 6 months after operation. In conclusion, our data indicate that cardiopulmonary bypass probably causes renal damage that is not sufficient to influence routine renal function parameters.