Site specific differences in vBMD and geometry in postmenopausal women with primary hyperparathyroidism.

PURPOSE: Primary Hyperparathyroidism (PHPT) is associated with catabolic effects at both trabecular and cortical bone. Mechanical loading is one of the most important natural anabolic stimuli for bone at all ages. The present study was designed to assess the impact of PHPT on vBMD and bone geometry using peripheral quantitative computed tomography (pQCT) at the radius and tibia, sites with similar structural characteristics, but subject to different loading conditions. METHODS: We evaluated the impact of PHPT on bone, by comparing the z-scores of volumetric Bone Mineral Density (vBMD) and indices of bone geometry simultaneously at the tibia and the radius by pQCT, skeletal sites with similar structure, but subject to different loading conditions. Forty-one postmenopausal women with PHPT and 79 controls, comprised the study group. RESULTS: At both trabecular and cortical sites, vBMD and bone geometry indices were significantly lower in patients compared with controls. In patients with PHPT, apart from a lower z-score for total vBMD (p = 0.01) at the radius, there was no other difference between the radius and the tibia at the trabecular sites. On the contrary, at cortical sites, the z-scores of cortical bone mineral content (p = 0.02), cortical vBMD (p = 0.01) and cortical cross-sectional area (p = 0.05) were significantly lower at the radius compared with the tibia, indicating that cortical bone at the weight bearing tibia might be less affected by the catabolic actions of continuous parathyroid hormone (PTH) exposure. PTH levels were positively associated with the difference in z-scores of cort BMD (r = 0.439, p < 0.01) indicating that in more severe cases, as expressed by higher PTH levels, the deleterious effects at the non-weight bearing radius might be accentuated. CONCLUSION: We found that in postmenopausal women with PHPT, both trabecular and cortical bone are adversely affected. However, at the weight bearing tibia as compared with the radius, the deleterious effects, especially on cortical bone, seem to be attenuated. TRIAL REGISTRATION NUMBER: NCT05426512, 21/06/2022, "retrospectively registered".

Residual blood loss in single use dialyzers: effect of different membranes and flux.

AIM/BACKGROUND: The aim of this study was to evaluate the residual blood loss in new type single use dialyzers under the usually prevailing conditions during hemodialysis and to investigate whether or not this loss is dependent on dialyzer membrane composition or flux characteristics. MATERIALS AND METHODS: In 158 hemodialysis (HD) patients, 158 single used dialyzers were studied in corresponding HD sessions. 52/158 dialyzers were made from modified cellulose (acetate, CA or triacetate, CTA) membrane and 106 from synthetic ones (58 with ethyl-vinyl-alcohol (EVAL), 48 with polyacrilonitrile (AN69)). Of those dialyzers 85/158 (58 EVAL+27CA) were low flux (LF) while the other 73 were high flux (HF). Patients underwent 4 hour HD sessions and at the end of the session blood was drawn for the measurement of hematocrit (Ht) and hemoglobin (Hb). Additionally, after the end of dialysis the used dialyzers were rinsed with 1000 mL of 0.05% NH(3) solution in distilled water. The wash was collected and subsequently Hb was measured using the benzidine method. From the volume of the solution and its concentration of Hb, total Hb of the solution was measured and blood loss in terms of red blood cell (RBC) volume was estimated by the use of the formula: RBC (mL) = Total Hb (g) in the solution x patient's Ht (ml/dL) / Patient's Hb (g/dL). For results to be comparable between dialyzers, RBC volume/m(2) of dialyzer membrane was expressed. In 5/158 patients blood loss was also estimated in 6 consecutive HD sessions using the same type of dialyzer. RESULTS: For the sum of the dialyzers, blood loss / dialyzer in terms of RBC volume, expressed as median (range), was 0.978 mL (0.01-23.9). There was statistically significant (p<0.001 or p<0.05) higher blood loss with the use of AN69 dialyzer than with the other three. RBC HF >RBC LF (p<0.001) constrained the first group of patients to use a 6% higher dosage of ferrum and 3.5% higher dosage of erythropoietin than the other group to achieve the optimal hemoglobulin values. No difference existed regarding RBC between CA, CTA and EVAL membranes. RBC measured in the small group of 5/158 patients for 6 consecutive HD sessions with the same dialyzer showed a wide range of RBC loss indicating an effect of the human factor. CONCLUSIONS: Blood loss during HD sessions due to residual blood cell volume inside dialyzers is usually slight using new type single use dialyzers but, sometimes, it can be significant and may contribute to the development or deterioration of preexisting iron deficiency anemia. The results of this study indicated that this loss can be attributed to the membrane composition of the dialyzer or to the human factor and has nothing to do with the ultrafiltration coefficient of the dialyzer.

The decline of renal function slowed by very low phosphorus intake in chronic renal patients following a low nitrogen diet.

The rate of progression of renal failure has been evaluated in two homogenous groups of chronic renal patients with early insufficiency. In both groups the diet supplied the same amount of calories (approximately 35 Kcal/kg/day) and the protein intake was equally restricted (approximately, 0.6 g/kg/day); however, in Group 1 the phosphorus intake was lower (6.5 mg/kg/day) than in Group 2 (12 mg/kg/day). In both groups the rate of decline of creatinine clearance decreased when patients changed from a free mixed diet to the specially controlled diets, but in Group 1 (lower phosphorus intake) this change was much more marked than in Group 2. Elevated mean levels of serum phosphate and of urinary output of phosphate per unit of creatinine clearance, and elevated mean levels of serum iPTH were found in the patients of Group 2, whereas Group 1 patients had normal mean levels of serum phosphate and of iPTH, and the phosphaturia per unit of creatinine clearance was almost normal. The role of such abnormalities in urinary and serum phosphate, and of secondary hyperparathyroidism, on the progression of renal failure is discussed.