Parameters of high bone-turnover predict bone loss in renal transplant patients: a longitudinal study.

BACKGROUND: Osteoporosis is a serious complication of kidney transplantation. Various factors have been postulated to contribute to posttransplant bone loss, among them treatment with corticosteroids, the use of cyclosporine and cyclosporine-like agents, and persistent hyperparathyroidism. In a previous cross-sectional study of long-term renal transplant recipients, we observed that osteoporosis or osteopenia was present in 88% of patients. Because biochemical markers of bone formation (serum osteocalcin) and bone resorption (urine pyridinoline, PYD, and deoxypyridinoline, DPD) were elevated in the majority of study subjects, we hypothesized that elevated rates of bone-turnover contribute to posttransplant bone loss in long-term renal transplant patients. This study was performed to examine this hypothesis. METHODS: The study population was composed of 62 patients who were more than 1-year postrenal transplantation and who had preserved renal function. They were followed prospectively for 1 year. Biochemical markers of bone-turnover were measured at study entry, and patients were classified as having high bone-turnover based on elevated urinary levels of at least one marker of bone resorption (i.e., PYD or DPD) and/or serum osteocalcin (group 1). If none of these were present, they were classified as having normal bone-turnover (group 2). Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DEXA) at time of entry into the study and again after 1 year of follow-up. The changes in BMD at the lumbar spine, hip, and wrist over the period of the study were compared between the high and normal bone-turnover groups. RESULTS: Forty-three patients (69%) were classified as having high bone-turnover (Group 1), and 19 patients (31%) were classified as having normal bone-turnover (Group 2). There was a statistically significant difference in change in BMD between the two groups at the lumbar spine (-1.11+/-0.42%, high bone-turnover, vs. 0.64+/-0.54%, normal bone-turnover; P=0.02) and the hip (-0.69+/-0.38%, high bone-turnover, vs. 1.36+/-0.66%, normal bone-turnover; P=0.006). Whereas group 2 had stable bone mass, group 1 exhibited bone loss at these skeletal sites. CONCLUSIONS: Our results indicate that bone loss is greater in renal transplant recipients with elevated biochemical markers of bone-turnover, suggesting that these markers may be useful in identifying patients at risk for continued bone loss. These data support the hypothesis that continued bone loss in long-term renal transplant recipients is associated with high bone-turnover. If accelerated bone resorption does play a role in posttransplant bone loss, this would provide a strong rationale for use of antiresorptive therapy for the prevention and treatment of this complication.

Midodrine and cool dialysate are effective therapies for symptomatic intradialytic hypotension.

Intradialytic hypotension (IDH) is a morbid complication of hemodialysis (HD). Both midodrine, an oral selective alpha1 agonist, and cool dialysate have been reported as useful therapies for this problem. We performed this prospective crossover study to compare the efficacy of these two therapies, alone and in combination, for IDH. The study consisted of a control phase and three treatment phases: midodrine phase (10 mg oral dose pre-HD), cool dialysate phase (35.5 degrees C), and combination therapy phase (midodrine, 10 mg, and dialysate temperature, 35.5 degrees C). Each phase consisted of nine consecutive HD treatments. Eleven patients (six men, five women; mean age, 67.5 years) with known symptomatic IDH were studied. This cohort was followed up in terms of blood pressure measurements (pre-HD blood pressure, lowest intradialytic blood pressure, post-HD blood pressure), weights, laboratory values, and interventions for IDH. The lowest intradialytic blood pressures were significantly better with midodrine and cool dialysate compared with the control phase (systolic blood pressure [SBP], 103.9 +/- 4.1 [mean +/- standard error of the mean] and 102.6 +/- 2.9 v 90.6 +/- 2.5 mm Hg, respectively; P < 0.001), as were the post-HD blood pressures (SBP, 116.9 +/- 4.0 and 118.2 +/- 3.5 v 109.0 +/- 2.1 mm Hg; P < 0.01). In addition, the lowest intradialytic blood pressures were significantly better with the combination phase compared with the control phase (SBP, 103.7 +/- 4.2 v 90.6 +/- 2.5 mm Hg; P < 0.001), as were the post-HD blood pressures (SBP, 122.1 +/- 4.6 v 109.0 +/- 2.1 mm Hg; P < 0.01). There was a significant reduction in the number of nursing interventions performed and volume of saline infused for IDH with midodrine and cool dialysate compared with control. There was a trend toward amelioration of hypotensive symptoms with both therapies. Laboratory values, including Kt/V, did not change significantly with either midodrine or cool dialysate. This prospective study shows that both midodrine and cool dialysate are effective therapies for symptomatic IDH. There does not seem to be additional benefit when these two therapies are used in combination.

Midodrine is effective and safe therapy for intradialytic hypotension over 8 months of follow-up.

Intradialytic hypotension (IDH) is a common and frustrating complication of hemodialysis. Certain end stage renal disease (ESRD) patients recurrently manifest this disabling condition. Both patient-specific factors (autonomic insufficiency, cardiac disease) and dialysis treatment-related factors (ultrafiltration, increased core body temperature) are thought to have significant causative roles. Most therapeutic interventions to date have been either unsuccessful or poorly tolerated. However, recent studies have shown that midodrine, an oral peripheral alpha-1 adrenergic agonist, is an effective and safe therapy for symptomatic IDH in the short-term. We report our experience with the predialysis use of midodrine for IDH in 13 hemodialysis (HD) patients over a 5 to 8 month period. Thirteen patients (8 male, 5 female, mean age 63.9 yrs) with recurrent symptomatic IDH were given midodrine 10 mg orally 30 min before each HD session. Blood pressures (pre-HD BP, lowest intradialytic [ID] BP, post-HD BP) and body weights were tracked for each HD treatment. Values for 10 HD sessions prior to midodrine therapy (Baseline) were compared to values (10 HD sessions each) during the 1st, 5th and 8th month of midodrine therapy. Data were analyzed using ANOVA for repeated measures and paired t-tests, with each patient serving as his/her own control. Patients were monitored for 5 months (n = 13) and 8 months (n = 8), respectively. All lowest intradialytic BPs, post-HD SBPs, and MAPs were significantly improved (p <0.05) on midodrine therapy. This effect was maintained during all periods of follow-up. There was no significant difference in mean albumin, hematocrit, Kt/V, calcium, and sodium between baseline and all periods of follow-up. Mean ultrafiltration volume per HD session was not significantly different than baseline over the course of study. A subjective improvement in hypotensive symptoms was also noted. Importantly, there were no adverse reactions to midodrine in all periods of follow-up. Midodrine appears to be an effective and safe treatment for HD patients with symptomatic IDH, and remains beneficial when used for an extended period of time.