Résumé
Introdução: Efetuado o tratamento cirúrgico do hiperparatireoidismo secundário, pode sobrevir hipoparatireoidismo. Um recurso terapêutico corrente é auto-implantar fragmentos paratireóideos criospreservados. A função do tecido criopreservado não é bem compreendida e preditores de função são de interesse. Objetivo: Analisar a relação entre o aspecto morfológico do tecido criopreservado à microscopia óptica e a função subseqüente deste tecido auto-implantado. Métodos: Análise retrospectiva do aspecto observado à microscopia óptica de alguns fragmentos de tecido implantado em pacientes com hipoparatireoidismo após paratireoidectomia total feita para tratamento de hiperplasia secundária. As imagens observadas foram correlacionadas à função do implante em dois grupos: um com microscopia normal e outro com autólise. Os níveis de hormônio da paratireóide (PTH) foram analisados um ano após o implante. O auto-implante de tecido criopreservado foi considerado funcional quando os níveis sistêmicos de PTH eram maiores que 15pg/ml. Resultados: Quinze pacientes foram incluídos no estudo. Desses, a função do implante pode ser demonstrada em seis (40%). A autólise foi achada em dois casos, ambos sem sinal de funcionamento. Em 13 pacientes, o tecido implantado era normal à microscopia óptica. Apesar dessa morfologia normal, em sete (53,8%) casos não havia funcionamento mesmo após um ano após a operação; apenas seis (46,2%) estão funcionais. Conclusões: A microscopia óptica convencional parece ter valor limitado para predizer a eventual função do tecido paratireóideo criopreservado após seu auto-implante. A autólise pode ser um indicador de má função.
Introduction: Hypoparathyroidism may ensue after the surgical treatment of secondary hyperparathyroidism. Implantation of cryopreserved parathyroid tissue is an option to revert the state of hypoparathyroidism after total parathyroidectomy for secondary hyperplasia. The function of cryopreserved tissue is not fully understood and function predictors are of interest. Objective: To analyze the relationship between optical microscopy aspect of cryopreserved tissue and its subsequent function after autograft. Methods: We analyzed retrospectively the optical microscopy findings of some fragments of implanted tissue in patients with hypoparathyroidism after total parathyroidectomy for secondary hyperplasia. These findings were correlated to the graft function. They were divided in one group with normal optical microscopy and another one with the presence of autolysis. PTH levels were analyzed one year after implant. Function of the cryopreserved graft was considered when systemic levels of PTH were greater than 15pg/ml. Results: Fifteen patients were included in this study. Of those, graft function was demonstrable in six (40%). Autolysis was found in two cases, without any sign of PTH secretion on both. In 13 patients, optical microscopy was normal. Despite this gross morphological normality, seven (53.8%) implants did not work after one year and only six (46.2%) are working. Conclusion: Conventional optical microscopy seems to play a limited role in predicting the outcome of parathyroid autografts. Autolysis may be a bad sign for future autograft function.
Résumé
Bone tissue alterations and vascular calcification (VC) are commonly found in patients with chronic renal failure (CKD). The importance of phosphorus (P) and parathyroid hormone (PTH) is not clear, yet. An in vitro study showed that inorganic phosphate was able to transform vascular smooth muscle cells (VSMC) into calcifying cells confirmed for up-expression of Runx2 in these cells. Besides, it has been demonstrated the in vivo expression of Runx2 in intimal and medial VSMC in calcified arteries of CKD patients. We evaluated the effect of phosphorus (P) and parathyroid hormone (PTH) on bone remodeling and on the expression of bone proteins (Runx2, Osteoprotegerin, type I Collagen, Osteocalcin, Osteopontin and NF?B) in aortic valve and heart in experimental uremia. Wistar rats were submitted to parathyroidectomy, nephrectomy (Nx) and continuous infusion of 1-34 rat PTH in physiologic or 5 times the normal values. The diet was identical, however the P content was low (LP: 0,2%) or high (HP: 1,2%). We performed biochemical, histomorphometric, imuno-histochemistry and RT-PCR analysis. Rats submitted to Nx developed renal failure. The P overload contributed to loss bone volume independent of uremia. Besides Nx animals that received high PTH doses bone loss was slight probably because of the anabolic effect of PTH, which was attenuated by the phosphorus overload toxic. VC was only observed in Nx animals that received high PTH doses independently of P overload. However, the P overload with physiologic PTH doses induced phenotypic changes in VSMC that was confirmed for the up-expression of Runx2 on aorta of these animals. The high concentrations of P and PTH promoted histological changes on expression of osteoprotegerin and type I Collagen in calcified arteries and heart. This study does not established ideal levels of PTH sufficient for the maintenance of the bone integrity and also to prevent VC when animal are submitted to different P overload.