The Emerging Role of Nutritional Vitamin D in Secondary Hyperparathyroidism in CKD

In chronic kidney disease (CKD), hyperphosphatemia induces fibroblast growth factor-23 (FGF-23) expression that disturbs renal 1,25-dihydroxy vitamin D (1,25D) synthesis; thereby increasing parathyroid hormone (PTH) production. FGF-23 acts on the parathyroid gland (PTG) to increase 1α-hydroxylase activity and results in increase intra-gland 1,25D production that attenuates PTH secretion efficiently if sufficient 25D are available. Interesting, calcimimetics can further increase PTG 1α-hydroxylase activity that emphasizes the demand for nutritional vitamin D (NVD) under high PTH status. In addition, the changes in hydroxylase enzyme activity highlight the greater parathyroid 25-hydroxyvitmain D (25D) requirement in secondary hyperparathyroidism (SHPT); the higher proportion of oxyphil cells as hyperplastic parathyroid progression; lower cytosolic vitamin D binding protein (DBP) content in the oxyphil cell; and calcitriol promote vitamin D degradation are all possible reasons supports nutritional vitamin D (NVD; e.g., Cholecalciferol) supplement is crucial in SHPT. Clinically, NVD can effectively restore serum 25D concentration and prevent the further increase in PTH level. Therefore, NVD might have the benefit of alleviating the development of SHPT in early CKD and further lowering PTH in moderate to severe SHPT in dialysis patients.

Association of Histological Findings with Tc-99m Sestamibi Parathyroid Imaging in Hyperfunctional Parathyroid Gland

Background: Hyperthyroidism is a relatively common disorder that results from increased production of parathormone. Tc-99m sestamibi (MIBI) scanning is used for localization of abnormal parathyroid gland, with high reported sensitivities. However, there exists a group of patients in whom MIBI scan is either equivocal or negative. Objectives: The aim of this study was to see association of the histological features of pathologic parathyroid gland with MIBI scan in hyperfunctional parathyroid gland. Methodology: This retrospective study was conducted with primary hyperthyroidism who underwent MIBI scan. The data were collected from the record from January 2012 to December 2014 for a period of two years. All patients underwent parathyroid surgery followed by histopathological examination. According to oxyphil cell distribution patients are divided in three groups. Group I comprised of >25.0% oxyphil cell; group II included the 25 to 75% oxyphil cell and group III included >75% of oxyphil cell. Result: A total 56 patients with hypercalcaemia and high serum parathyroid hormone (PTH) level were studied. Mean age was 41.3(±19.8) years with a range of 21 to 63 years. MIBI scan was true positive in 34(60.7%) cases and false negative in 22(39.3%) cases. In group I MIBI scan was true positive in 4(36.3%) cases and false negative in 7(63.7%) cases. In group II MIBI scan showed positive in 17(62.9%) cases and negative in 10(37.1%) cases. In group III out of 18 patients 13(72.2%) showed MIBI scan positive whereas, 5(27.8%) showed negative scan. The sensitivity was 36.3% in group I whereas, 62.9% and 72.2% in group II and group III respectively. Conclusion: Based on these findings, it could be say that Tc–99m setamibi uptake correlate with parathyroid oxyphil cell content, and false negative scan can occur with parathyroid glands containing predominantly clear cell.Journal of National Institute of Neurosciences Bangladesh, 2016;2(1):14-18