The impact of shrunken pore syndrome in patient with rheumatic diseases on bone mineral metabolism

Abstract

The study aimed to investigate the influence of shrunken pore syndrome (SPS), defined as a cystatin C (CysC)-based estimated glomerular filtration rate (eGFR_CysC) <60% of the creatinine (Cr)-based eGFR (eGFR_Cr), on bone mineral density (BMD) in patients with rheumatic diseases. A total of 831 patients with rheumatic diseases were enrolled in the study. Patients were classified into the SPS group (G-SPS) and non-SPS group (G-nSPS). The correlation between the presence of SPS and BMD of the lumbar spine (BMD_LS), BMD of the femoral neck (BMD_FN), serum parathyroid hormone (PTH) level, chronic kidney dysfunction (CKD), and parameters were evaluated statistically. The prevalence of SPS was 4.0%. Serum PTH level, tartrate-resistant acid phosphatase-5b (TRACP-5b), and eGFR_Cr in the G-SPS were significantly higher than in the G-nSPS, whereas BMD_LS and BMD_FN in the G-SPS were significantly lower than in the G-nSPS. Serum PTH level was significantly correlated with CysC. BMD_LS had no significant correlation with BMD_FN. The presence of SPS was the only factor that demonstrated significant negative correlation with both BMD_LS and BMD_FN. Relationship between BMD_LS and the presence of SPS was present regardless of CKD stage; however, the negative relationship between BMD_LS and serum PTH was observed only in CKD stage 1 and 2 patients. BMD_FN demonstrated significant negative correlation with serum PTH in the group with progression of CKD. These results suggest that there is a serious potential risk of osteoporosis in patients with SPS and increased PTH, and BMD_LS poses a higher risk in CKD stage 1 and 2.

Keywords:

• Chronic kidney diseases
• shrunken pore syndrome
• bone mineral density
• parathyroid hormone
• calcium metabolism
• cystatin C

Acknowledgements

Authors thank X-ray technicians in their institutes for their concise measurement of DXA.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

IY collected and analyzed data and wrote rough draft.

SN proposed main concept of this study, collected part of data, and checked the manuscript.