Sinead Kinsella

Hyponatremia independent of osteoporosis is associated with fracture occurrence.

BACKGROUND AND OBJECTIVES Mild hyponatremia has traditionally been considered benign, but it may be associated with gait and attention deficits and an increased risk of falls that may result in fracture. A retrospective study was conducted to quantify the association of hyponatremia with fracture occurrence and to examine whether this relationship is independent of osteoporosis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study analyzed 1408 consecutive female patients who underwent bone mineral density measurement (Lunar IDXA) between September 1, 2006 and April 11, 2007 and who had available laboratory data. Self reported fracture occurrence was confirmed by radiology report or attendance at a fracture clinic. The significance and independence of the association of hyponatremia with fracture was quantified using logistic regression. RESULTS The mean (SD) serum sodium ([Na(+)]) was 140.6 (3.0) mmol/L; 59 (4.2%) had [Na(+)] < 135 mmol/L. Forty-five percent of subjects were osteoporotic and 18% had a prior fracture. Hyponatremia was present in 8.7% of those with versus 3.2% of those without a confirmed fracture (P < 0.001). On multivariate logistic regression analysis controlling for age, T-score, chronic kidney disease stage, osteoporotic risk factors (amenorrhea, family history, regular steroid use, smoking history, alcohol use, history of liver disease, and low-calcium diet), and osteoporosis treatments (calcium and vitamin D supplements, antiresorptives, and hormonal replacement therapy), [Na(+)] < 135 versus [Na(+)] >or= 135 mmol/L remained significantly and independently associated with fracture occurrence (P < 0.01). CONCLUSIONS Mild hyponatremia may be a readily identifiable and potentially modifiable risk factor for fracture.

Maintenance hemodialysis patients have high cumulative radiation exposure

Hemodialysis is associated with an increased risk of neoplasms which may result, at least in part, from exposure to ionizing radiation associated with frequent radiographic procedures. In order to estimate the average radiation exposure of those on hemodialysis, we conducted a retrospective study of 100 patients in a university-based dialysis unit followed for a median of 3.4 years. The number and type of radiological procedures were obtained from a central radiology database, and the cumulative effective radiation dose was calculated using standardized, procedure-specific radiation levels. The median annual radiation dose was 6.9 millisieverts (mSv) per patient-year. However, 14 patients had an annual cumulative effective radiation dose over 20 mSv, the upper averaged annual limit for occupational exposure. The median total cumulative effective radiation dose per patient over the study period was 21.7 mSv, in which 13 patients had a total cumulative effective radiation dose over 75 mSv, a value reported to be associated with a 7% increased risk of cancer-related mortality. Two-thirds of the total cumulative effective radiation dose was due to CT scanning. The average radiation exposure was significantly associated with the cause of end-stage renal disease, history of ischemic heart disease, transplant waitlist status, number of in-patient hospital days over follow-up, and death during the study period. These results highlight the substantial exposure to ionizing radiation in hemodialysis patients.

Moderate Chronic Kidney Disease in Women Is Associated with Fracture Occurrence Independently of Osteoporosis

Background: Chronic kidney disease (CKD) is associated with increased risk of fragility fracture but whether this is independent of osteoporosis is unclear. Methods: We conducted a retrospective cross-sectional study of 1,702 female patients referred for dual-energy X-ray absorptiometry (DXA) scanning (Lunar IDXA) between September 2006 and April 2007. Estimated glomerular filtration rate (eGFR; ml/min/1.73 m2) by Modification of Diet in Renal Disease was calculated within 1 year (median interval 4 weeks) of the DXA scan. The independent association of self-reported fracture occurrence with eGFR category was assessed using multivariate logistic regression. Results: Mean age (SD) was 61.7 (10.8) years; mean eGFR (SD) was 68.8 (12.2). The percentages of subjects with an eGFR of 75–89, 60–74, 30–59 and <30 was 34, 45, 20 and 0.8%, respectively. Forty-seven percent had osteoporosis. Mean T scores for the above eGFR categories were –2.2, –2.3, –2.5 and –3.0, respectively (p trend <0.001). Osteoporosis was significantly associated with eGFR on univariate analysis but not following adjustment for age. The percentage of patients with a fracture (29%) and with multiple prior fractures (3.5%) was higher at lower eGFR (p < 0.001, χ2 test). The adjusted odds ratios (95% confidence interval) of any prior fracture for eGFR 75–89, 60–74 and 30–59 were 1.0 (reference), 1.2 (0.9–1.6) and 1.4 (1.0–1.9), respectively, adjusting simultaneously for age, T score, risk factors and treatment for osteoporosis. Conclusion: Moderate CKD is a significant independent predictor of fracture occurrence.

Lack of Correlation between Calcium Intake and Serum Calcium Levels in Stable Haemodialysis Subjects

Background: The relationship between calcium intake and serum calcium level in hemodialysis patients is poorly understood. Methods: We quantify total oral calcium intake using detailed 7-day food diaries with 294 patient days of observation in 42 stable, non-diabetic hemodialysis subjects. Results: Mean (SD) albumin-corrected serum calcium was 9.84 mg/dl (0.8). The albumin-corrected serum calcium was low (<8.4 mg/dl) in 2 patients, low-normal (8.4–9.49) in 9 patients, high-normal (9.5–10.2) in 18 patients and high (>10.2) in 13 patients. Mean (SD) total (diet plus binder) oral calcium intake was 1996 mg/day (1,020); 16 patients (38%) had a total calcium intake >2,000 mg/day. Calcium intake and serum calcium were poorly correlated (Spearman rank method), r = 0.14, p = 0.39. Median calcium intakes were similar in those with normal (1,990 mg/day), high-normal (1,926 mg/day) and high calcium groups (1,713 mg/day), p = 0.73 (Kruskal-Wallis), p = 0.29 (linear test for trend). Forty-one percent (11/27) of patients who had serum calcium in the normal range had a calcium intake greater than 2 g/day, while 11.5% had a calcium intake greater than 3 g/day. In subjects with a parathyroid hormone (PTH) concentration <300 pg/ml (n = 20), the correlation between calcium intake and either uncorrected serum calcium or albumin-corrected serum calcium was stronger, r = 0.45, p = 0.05 and r = 0.38, p = 0.10, respectively, though there remained wide variability in calcium intake. Conclusion: Serum calcium is not a reliable indicator of calcium intake, especially at PTH ≥300 pg/ml. An excessive calcium intake may coexist with a normal serum calcium level.

Do patient-reported measures of symptoms and health status predict mortality in hemodialysis? An assessment of POS-S Renal and EQ-5D

Introduction Experience with the use of patient‐reported outcome measures such as EQ‐5D and the symptom module of the Palliative care Outcome Scale—Renal Version (POS‐S Renal) as mortality prediction tools in hemodialysis is limited.

Serum phosphate varies with degree of proteinuria in nephrotic syndrome and is associated with elevated pulse wave velocity.

BACKGROUND The occurrence of vascular stiffness in the setting of the nephrotic syndrome and the influence of serum phosphate on this association is unknown. METHODS A retrospective study of 42 prevalent, adult nephrotic patients who underwent carotid-femoral pulse wave velocity (PWV) measurement, a median of 24 months after kidney biopsy. Elevated PWV was determined using published age-specific reference ranges. The association, statistical significance and independence of serum phosphate with spot urine protein-creatinine ratio (PCR) and the association of phosphate with PWV was examined. RESULTS Mean PCR was 5.5 g/g and mean eGFR (CKD-EPI) was 70 mL/min/1.73 m2. Serum phosphate was statistically significantly associated with severity of nephrotic syndrome independently of eGFR and age. Median (intra-quartile range) PWV was 7 m/s (4-11), with a linear trend for higher PWV across tertile of average serum phosphate over follow-up, P<.001. Twenty subjects (48%) had elevated age-specific PWV, which on logistic regression was statistically significantly associated with mean serum phosphate, OR (95% CI) per 0.1 mmol/L: 2.7 (1.5, 4.9), P = .001, which in separate analyses was independent of eGFR and other laboratory data. CONCLUSIONS In this cohort of patients with the nephrotic syndrome serum phosphate was commonly elevated, despite well preserved eGFR, which was significantly and independently associated with elevated PWV over follow-up.

Posttransplant Lymphoproliferative Disorders in Irish Renal Transplant Recipients: Insights From a National Observational Study

Background Posttransplant lymphoproliferative disorders (PTLD) are a common malignancy after renal transplantation with a high incidence of PTLD described in the first posttransplant year. We sought to determine incidence and risk determinants of PTLD in Irish kidney transplant recipients. Methods Retrospective observational study of 1996 adult first kidney transplant recipients between 1991 and 2010 in the Republic of Ireland. Recipients were cross-referenced with the National Cancer Registry to determine incidence of PTLD. Kaplan-Meier analysis was performed for PTLD-free survival, allograft survival, and patient survival after PTLD. Cox proportional hazards models were used to identify independent risk factors for PTLD in our population. Results We identified 31 cases of PTLD during the study period. Histological subgroups included: early lesions (n = 1); polymorphic PTLD (n = 1); monomorphic PTLD (n = 27), Hodgkin disease (n = 2). Median time to PTLD diagnosis was 8.3 (range, 1.2-13.9) years. Cumulative incidence (95% CI) of PTLD at 1, 2, 3, 5, 10, and 15 years was 0%, 0.16% (0.05-0.5%), 0.21% (0.08-0.57%), 0.21% (0.08-0.57%), 1.76% (1.15-2.69%), and 3.07% (2.1-4.43%), respectively. Allograft survival after PTLD diagnosis was 94.4% (66.6-99.2%) at 5 years. Patient survival after PTLD diagnosis was 64% at 1 year, 53% at 2 years, 48% at 5 years, and 37% at 10 years. No risk factors for PTLD were identified. Conclusions We found a paucity of early onset PTLD in our cohort with no cases in the first posttransplant year. Potential contributing factors included a high prevalence of previous Epstein-Barr virus exposure and a relatively low immunological risk profile in our recipient cohort compared with prior studies. Further studies are required to reevaluate the epidemiology of PTLD in the modern era of transplant immunosuppression.