【Research Publication】Study on Renal Tubular Calcium Phosphate Microcrystallopathy and Age-Related Kidney Function Decline Published in Clinical Kidney Journal

## Overview
Medical Education Inc. (Headquarters: Suginami-ku, Tokyo; Representative Director: Takashi Ochiai) announces that the research paper titled "Renal tubular calcium phosphate microcrystallopathy and age-related kidney function decline: The Aging Kidney Study," authored by Dr. Keisei Kosaki and colleagues at the Faculty of Health and Sport Sciences, University of Tsukuba, has been published in the academic journal "Clinical Kidney Journal."

The study involved a 5-year prospective cohort study of 308 adults, examining the relationship between the estimated proximal tubular fluid phosphate concentration (ePTFp) calculated from blood and urine data and kidney function decline (eGFR slope). High baseline ePTFp was independently associated with accelerated kidney function decline even after adjusting for covariates.

The figure featured in this paper was produced by MEDICAL FIG., a service operated by Medical Education Inc.

## Figure Used in the Research
The figure is a conceptual diagram showing the position of the ePTFp and eGFR slope evaluated in this study within the flow from phosphorus loading to changes in renal tubules, CaPi formation, and kidney function decline. It introductory organizes the relationship between study subjects and evaluation indicators.

## Researcher Information
Researcher: Dr. Keisei Kosaki
Affiliation: Faculty of Health and Sport Sciences, University of Tsukuba
Co-authors: Keisei Kosaki, Shoya Mori, Masahiro Matsui, Masaki Yoshioka, Jiyeon Park, Natsumi Nishitani, Shun Yoshikoshi, Wataru Murasaki, Chie Saito, Masahiko Gosho, Seiji Maeda, Makoto Kuro-o, Kunihiro Yamagata

## Role of the Figure in This Research
This figure was created as an introductory conceptual diagram showing which part of the mechanism from phosphorus loading to microcrystal formation and CKD progression this clinical study evaluates and with which indicators.
Designed to allow visual understanding of the association with kidney function decline by mapping the longitudinal relationship between ePTFp and eGFR.

## Key Considerations in Figure Production
In production, we organized the positions of the ePTFp indicator and the target kidney function decline within the overall research, creating a structure that can be grasped as a relationship with the entire mechanism.
Furthermore, by arranging each element step-by-step in the flow from phosphorus loading through changes in renal tubules to kidney function decline, we designed it so that readers can follow the causal connections of the information.
Also, by visually emphasizing the renal tubule region and depicting calcium phosphate (CaPi) with morphological characteristics, attention was paid to the focus and distinguishability of elements in the figure.

## Publication Information
Paper Title: Renal tubular calcium phosphate microcrystallopathy and age-related kidney function decline: The Aging Kidney Study
Journal: Clinical Kidney Journal
Publication Date: March 16, 2026
DOI: 10.1093/ckj/sfag085

## About Medical Education Inc. / MEDICAL FIG.
Medical Education Inc. (Part of the SCICUS Group, Headquarters: Suginami-ku, Tokyo; Representative Director: Takashi Ochiai) supports researchers and experts in organizing their thinking and visualizing research structures, primarily in the fields of medicine, life sciences, and healthcare.

MEDICAL FIG. is a visualization support service provided by the company for the medical and research fields. Based on the background of research content and experimental systems, they support the communication of research results through the production of paper figures, graphical abstracts, and schematic diagrams.