Optimization of the Tartrate-Resistant Acid Phosphatase Detection by Histochemical Method

According to the new KDIGO (Kidney Disease Improving Global Outcomes) guidelines, the term of renal osteodystrophy, should be used exclusively in reference to the invasive diagnosis of bone abnormalities. Due to the low sensitivity and specificity of biochemical serum markers of bone remodelling,the performance of bone biopsies is highly stimulated in dialysis patients and after kidney transplantation. The tartrate-resistant acid phosphatase (TRACP) is an iso-enzyme of the group of acid phosphatases, which is highly expressed by activated osteoclasts and macrophages. TRACP in osteoclasts is in intracytoplasmic vesicles that transport the products of bone matrix degradation. Being present in activated osteoclasts, the identification of this enzyme by histochemistry in undecalcified bone biopsies is an excellent method to quantify the resorption of bone. Since it is an enzymatic histochemical method for a thermolabile enzyme, the temperature at which it is performed is particularly relevant. This study aimed to determine the optimal temperature for identification of TRACP in activated osteoclasts in undecalcified bone biopsies embedded in methylmethacrylate. We selected 10 cases of undecalcified bone biopsies from hemodialysis patients with the diagnosis of secondary hyperparathyroidism. Sections of 5 μm were stained to identify TRACP at different incubation temperatures (37º, 45º, 60º, 70º and 80ºC) for 30 minutes. Activated osteoclasts stained red and trabecular bone (mineralized bone) was contrasted with toluidine blue. This approach also increased the visibility of the trabecular bone resorption areas (Howship lacunae). Unlike what is suggested in the literature and in several international protocols, we found that the best results were obtained with temperatures between 60ºC and 70ºC. For technical reasons and according to the results of the present study, we recommended that, for an incubation time of 30 minutes, the reaction should be carried out at 60ºC. As active osteoclasts are usually scarce in a bone section, the standardization of the histochemistry method is of great relevance, to optimize the identification of these cells and increase the accuracy of the histomosphometric results. Our results, allowing an increase in osteoclasts contrast, also support the use of semi-automatic histomorphometric measurements.

Stress-Related Mucosal Disease: Incidence of Bleeding and the Role of Omeprazole in its Prophylaxis

BACKGROUND: Upper gastrointestinal bleeding is the severe complication of stress-related mucosal disease in hospitalized patients. In intensive care units (ICU), risk factors are well defined and only mechanical ventilation and coagulopathy proved to be relevant for significant bleeding. On the contrary, in non-ICU settings there is no consensus about this issue. Nevertheless, omeprazole is still widely used in prophylaxis of bleeding. The objective of our study was to evaluate the relevance of stress-related mucosal disease bleeding in patients admitted to an internal medicine ward, and the role of omeprazole in its prophylaxis. METHODS: We conducted a retrospective study in which we analysed consecutive patients who were admitted to our ward over a year. We recorded demographic characteristics of the patients, potential risk factors for stress-related mucosal disease (clinical data, laboratory, and medication), administration of prophylactic omeprazole, and total cost of this prophylaxis. Patients with active gastrointestinal bleeding on the admission were excluded. We recorded every upper gastrointestinal bleeding event with clinical relevance. RESULTS: Five hundred and thirty-five patients, mean age 70 years, mean length of stay 9.6+/-7.7 days; 140 (26.2%) patients were treated with 40 mg of omeprazole intravenously, 193 (36.1%) with 20mg of omeprazole orally, and 202 (37.8%) patients had no prophylaxis. There was only one episode (0.2%) of clinically relevant bleeding. CONCLUSION: In patients admitted to an internal medicine ward, incidence of upper gastrointestinal bleeding as a complication of stress-related mucosal disease is low. We found that there is no advantage in prophylaxis with omeprazole.