Journal: Pflugers Archiv
Article Title: Controlled dietary phosphate loading in healthy young men elevates plasma phosphate and FGF23 levels
doi: 10.1007/s00424-024-03046-4
Figure Lengend Snippet: Phosphatropic hormones after 5 days of low- or high-phosphate (P i ) diet. Levels of A serum parathyroid hormone (PTH), B plasma intact fibroblast growth factor 23 (iFGF23), C plasma C-terminal FGF23 (cFGF23), D the ratio of iFGF23 (ng/l)/cFGF23 (ng/l) as well as serum E calcidiol, and F calcitriol, and G plasma soluble Klotho, and H Fetuin-A on the final day of both the 5-day low and high P i diet. One reference unit (RU)/ml corresponds to 2 ng/l cFGF23. Blue dots represent differences (Δ) between high P i diet and low P i diet expressed as mean difference ± 95% confidence interval and blue dashed line represents the zero line of the right y-axis. Data was analyzed by the paired t -test ( A – E ) or Wilcoxon test ( F–H ), n = 10, * p < 0.05
Article Snippet: Tubular maximum P i reabsorption (TmP/GFR) was calculated by using the fractional tubular reabsorption (TRP) of P i with the following equations using spot urine [ ]: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\begin{array}{l}TRP=1-\left[\left(\frac{{U}_{Pi}}{{P}_{Pi}}\right)*\left(\frac{{P}_{Cr}}{{U}_{Cr}}\right)\right]\\ TRP \le 0.86 \to TmP/GFR=TRP*{P}_{Pi}\\ TRP>0.86 \to TmP/GFR=\left(0.3*\frac{TRP}{1-\left(0.8*TRP\right)}\right)*{P}_{Pi}\end{array}$$\end{document} T R P = 1 - U Pi P Pi ∗ P Cr U Cr T R P ≤ 0.86 → T m P / G F R = T R P ∗ P Pi T R P > 0.86 → T m P / G F R = 0.3 ∗ TRP 1 - 0.8 ∗ T R P ∗ P Pi Daily fractional excretion of P i (FEP i ) was calculated by the following equation using the absolute 24-h urine P i and creatinine: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$FE{P}_{i}=\frac{{(U}_{Pi}*{P}_{Cr})}{{(P}_{Pi}*{U}_{Cr})}*100$$\end{document} F E P i = ( U Pi ∗ P Cr ) ( P Pi ∗ U Cr ) ∗ 100 Daily renal filtered P i load was calculated with the following equation: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Renal\;P_iload/day=\left(\frac{U_{Cr}\ast U_{volume}}{P_{Cr}\ast1440}\right)\ast P_{Pi}$$\end{document} R e n a l P i l o a d / d a y = U Cr * U volume P Cr * 1440 * P Pi Plasma iFGF23, cFGF23, Fetuin-A, and urinary metanephrine were measured with the human iFGF23 and cFGF23 enzyme-linked immunosorbent assay (ELISA) (iFGF23 and cFGF23, Quidel, 60–6600 and 60–6100, respectively), Fetuin-A ELISA (R&D Systems, DFTA00, Lot P413286), and the Metanephrine Urine ELISA (Demeditec Diagnostics GmbH, DEE8400) according to manufacturers’ protocols.
Techniques: Clinical Proteomics