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Iohexolclearance

Kalkylator

Flerpunkts- och enpunkts-GFR från plasmaiohexol med slope-intercept, valbara korrektionsformler och koncentration–tid-kurva.

Ange tid och koncentration för provet.

Absolut GFR—mL/min
Relativ GFR—mL/min/1,73m²
Patient
år
kg
cm
Dos & injektion
mL
ProverAntal
#
Provtid
Konc (mg/L)
1
Avancerat
Inställningar
BSA-formel
1-punktsformel
eECV-formel
Härledda värden
BMI—kg/m²
BSA—m²
eECV—L
Dos2590mg iohexol
Referenser

Flerpunktsmetod och korrektioner

  • [1] Bröchner-Mortensen J. (1972). A simple method for the determination of glomerular filtration rate. Scandinavian Journal of Clinical and Laboratory Investigation, 30(3), 271–274. DOI ↗
  • [2] Jødal L, Brøchner-Mortensen J. (2009). Reassessment of a classical single injection 51Cr-EDTA clearance method… Part I: Analytically correct relationship between total and one-pool clearance. Scandinavian Journal of Clinical & Laboratory Investigation, 69(3), 305–313. DOI ↗
  • [3] Brøchner-Mortensen J, Jødal L. (2009). Reassessment… Part II: Empirically determined relationships between total and one-pool clearance. Scandinavian Journal of Clinical & Laboratory Investigation, 69(3), 314–322. DOI ↗
  • [4] Fleming JS. (2007). An improved equation for correcting slope-intercept measurements of glomerular filtration rate for the single exponential approximation. Nuclear Medicine Communications, 28(4), 315–320. DOI ↗
  • [5] Ng DK, Schwartz GJ, Jacobson LP, et al. (2011). Universal GFR determination based on two time points during plasma iohexol disappearance. Kidney International, 80(4), 423–430. DOI ↗

Enpunktsmetoder

  • [6] Jacobsson L. (1983). A method for the calculation of renal clearance based on a single plasma sample. Clinical Physiology, 3(4), 297–305. DOI ↗
  • [7] Granerus G, Jacobsson L. (1985). Beräkning av 51Cr-EDTA single injection clearance – jämförelse mellan flerpunkts- och enpunktsformel. Svensk förening för medicinsk radiologi, Förhandlingar, 19, 71–73.
  • [8] Fleming JS, Persaud L, Zivanovic MA. (2005). A general equation for estimating glomerular filtration rate from a single plasma sample. Nuclear Medicine Communications, 26(8), 743–748. PMID: 16000995. PubMed ↗
  • [9] Ham HR, Piepsz A. (1991). Estimation of glomerular filtration rate in infants and in children using a single-plasma sample method. Journal of Nuclear Medicine, 32(6), 1294–1297.
  • [10] Groth S, Aasted M. (1981). 51Cr-EDTA clearance determined by one plasma sample. Clinical Physiology, 1(4), 417–425. PMID: 6800683.
  • [11] Groth S, Aasted M. (1984). 51Cr-EDTA clearance determined by one plasma sample in children. Clinical Physiology, 4(1), 75–83. PMID: 6421538.
  • [12] Christensen AB, Groth S. (1986). Determination of 99mTc-DTPA clearance by a single plasma sample method. Clinical Physiology, 6(6), 579–588. PMID: 3539465.
  • [13] Watson WS. (1992). A simple method of estimating glomerular filtration rate. European Journal of Nuclear Medicine, 19, 827. (Letter to the editor).
  • [14] Stake G, Monclair T. (1991). A single plasma sample method for estimation of the GFR in infants and children using iohexol. I: Establishment of a body weight-related formula for the distribution volume of iohexol. Scandinavian Journal of Clinical and Laboratory Investigation, 51(4), 335–342. PMID: 1947718. DOI ↗
  • [15] Stake G, Monn E, Rootwelt K, Monclair T. (1991). A single plasma sample method… II: Establishment of the optimal plasma sampling time and a comparison with the 99mTc-DTPA method. Scandinavian Journal of Clinical and Laboratory Investigation, 51(4), 343–348. PMID: 1947719. DOI ↗
  • [16] Gref M, Karp K. (2007). GFR determination in adults with a single-sample iohexol plasma clearance method based on the mean sojourn time. Nephrology Dialysis Transplantation, 22(11), 3166–3173. PMID: 17675331. DOI ↗

BSA-formler

  • [17] Du Bois D, Du Bois EF. (1916). A formula to estimate the approximate surface area if height and weight be known. Archives of Internal Medicine, 17(6_2), 863–871. DOI ↗
  • [18] Haycock GB, Schwartz GJ, Wisotsky DH. (1978). Geometric method for measuring body surface area: A height-weight formula validated in infants, children, and adults. The Journal of Pediatrics, 93(1), 62–66. DOI ↗
  • [19] Mosteller RD. (1987). Simplified calculation of body-surface area. New England Journal of Medicine, 317(17), 1098. DOI ↗
  • [20] Gehan EA, George SL. (1970). Estimation of human body surface area from height and weight. Cancer Chemotherapy Reports, 54(4), 225–235.
  • [21] Fujimoto S, Watanabe T, Sakamoto A, Yukawa K, Morimoto K. (1968). Studies on the physical surface area of Japanese. 18. Calculation formulas in three stages over all ages. Nippon Eiseigaku Zasshi, 23(5), 443–450. DOI ↗
  • [22] Schlich E, Schumm M, Schlich M. (2010). 3-D-Body-Scan als anthropometrisches Verfahren zur Bestimmung der spezifischen Körperoberfläche. Ernährungs Umschau, 57(4), 178–183.

Extracellulärvolym (eECV)

  • [23] Bird NJ, Henderson BL, Lui D, Ballinger JR, Peters AM. (2003). Indexing glomerular filtration rate to suit children. Journal of Nuclear Medicine, 44(7), 1037–1043. PMID: 12843217. PubMed ↗
  • [24] Bird NJ, Peters AM. (2021). New gender-specific formulae for estimating extracellular fluid volume from height and weight in adults. Nuclear Medicine Communications, 42(1), 58–62. DOI ↗
  • [25] Peters AM, Henderson BL, Lui D, et al. (2011). Extracellular fluid volume and glomerular filtration rate in 1876 healthy potential renal transplant donors… Nephrology Dialysis Transplantation, 26(4), 1429–1437. DOI ↗
  • [26] Peters AM. (2011). Re-evaluation of the new Jødal–Brøchner-Mortensen equation for one-pool correction of slope-intercept measurement of GFR. Nuclear Medicine Communications, 32(5), 375–380. PMID: 21301378. DOI ↗

Flerpunktsmetodens grund (slope-intercept)

  • [27] Sapirstein LA, Vidt DG, Mandel MJ, Hanusek G. (1955). Volumes of distribution and clearances of intravenously injected creatinine in the dog. American Journal of Physiology, 181(2), 330–336. PMID: 14376619. DOI ↗
  • [28] Chantler C, Garnett ES, Parsons V, Veall N. (1969). Glomerular filtration rate measurement in man by the single injection method using 51Cr-EDTA. Clinical Science, 37(1), 169–180. PMID: 4980763.
Metodik och formler
Jacobsson [6]

Steg 1: plasmahalten konverteras till mg/mL och ett startvärde för eECV beräknas.

Ct∗=Ct1000C_t^{*}=\frac{C_t}{1000}
V0={166W+2490,man95W+6170,kvinnaV_{0}=\begin{cases}166W+2490, & \text{man}\\ 95W+6170, & \text{kvinna}\end{cases}

Steg 2: initial clearance skattas och itereras till konvergens.

Cl(0)=ln⁡ ⁣(DosCt∗V0)tV0+0.0016Cl^{(0)}=\frac{\ln\!\left(\frac{\text{Dos}}{C_t^{*}V_0}\right)}{\frac{t}{V_0}+0.0016}
r(i)=0.495(1+1−0.0049 Cl(i−1)),m(i)=0.991−0.00122 Cl(i−1)r^{(i)}=0.495\left(1+\sqrt{1-0.0049\,Cl^{(i-1)}}\right),\quad m^{(i)}=0.991-0.00122\,Cl^{(i-1)}
V′(i)=V0m(i),Cl(i)=ln⁡ ⁣(DosCt∗V′(i))tV′(i)−ln⁡(r(i))Cl(i−1)V'^{(i)}=\frac{V_0}{m^{(i)}},\quad Cl^{(i)}=\frac{\ln\!\left(\frac{\text{Dos}}{C_t^{*}V'^{(i)}}\right)}{\frac{t}{V'^{(i)}}-\frac{\ln(r^{(i)})}{Cl^{(i-1)}}}

Steg 3: relativt mGFR normaliseras till 1,73 m² kroppsyta och optimal provtid skattas.

mGFR=Cl,mGFR1.73=mGFR⋅1.73BSA,topt=V′mGFR⋅160mGFR=Cl,\quad mGFR_{1.73}=mGFR\cdot\frac{1.73}{BSA},\quad t_{opt}=\frac{V'}{mGFR}\cdot\frac{1}{60}
Flerpunktsmetod och korrektioner

Log-linjär regression på eliminationsfasen:

ln⁡C(t)=a+bt,b<0,k=−b,C0=ea\ln C(t)=a+bt,\quad b\lt0,\quad k=-b,\quad C_0=e^{a}

Okorrigerad clearance — absolut samt normaliserad till 1,73 m²:

Cluncorr=DosC0⋅k⋅1000,Cluncorr∗=Cluncorr⋅1.73BSACl_{uncorr}=\frac{\text{Dos}}{C_0}\cdot k\cdot 1000,\qquad Cl_{uncorr}^{*}=Cl_{uncorr}\cdot\frac{1.73}{BSA}
[27, 28]

Brøchner-Mortensen korrigerar absolut clearance:

mGFR=0.99078 Cluncorr−0.001218 Cluncorr2mGFR=0.99078\,Cl_{uncorr}-0.001218\,Cl_{uncorr}^{2}
[1]

JBM, Fleming och Ng är definierade för clearance normaliserad till 1,73 m² och appliceras därför på Cluncorr∗Cl_{uncorr}^{*}:

mGFR1.73=Cluncorr∗1+(0.00185⋅BSA−0.3)Cluncorr∗mGFR_{1.73}=\frac{Cl_{uncorr}^{*}}{1+\left(0.00185\cdot BSA^{-0.3}\right)Cl_{uncorr}^{*}}
[2, 3]
mGFR1.73=Cluncorr∗1+0.0017 Cluncorr∗mGFR_{1.73}=\frac{Cl_{uncorr}^{*}}{1+0.0017\,Cl_{uncorr}^{*}}
[4]
mGFR1.73=Cluncorr∗1+0.0012 Cluncorr∗mGFR_{1.73}=\frac{Cl_{uncorr}^{*}}{1+0.0012\,Cl_{uncorr}^{*}}
[5]

Absolut och relativt GFR konverteras med:

mGFR1.73=mGFR⋅1.73BSAmGFR_{1.73}=mGFR\cdot\frac{1.73}{BSA}
BSA-formler

Samtliga formler använder vikt W i kg och längd H i cm.

BSADu Bois=0.007184⋅W0.425⋅H0.725BSA_{Du\,Bois}=0.007184\cdot W^{0.425}\cdot H^{0.725}
[17]
BSAHaycock=0.024265⋅W0.5378⋅H0.3964BSA_{Haycock}=0.024265\cdot W^{0.5378}\cdot H^{0.3964}
[18]
BSAMosteller=H⋅W3600BSA_{Mosteller}=\sqrt{\frac{H\cdot W}{3600}}
[19]
BSAGehan=0.0235⋅W0.51456⋅H0.42246BSA_{Gehan}=0.0235\cdot W^{0.51456}\cdot H^{0.42246}
[20]
BSAFujimoto=0.008883⋅W0.444⋅H0.663BSA_{Fujimoto}=0.008883\cdot W^{0.444}\cdot H^{0.663}
[21]
BSASchlich, kvinna=0.000975482⋅W0.46⋅H1.08BSA_{Schlich,\,kvinna}=0.000975482\cdot W^{0.46}\cdot H^{1.08}
[22]
BSASchlich, man=0.000579479⋅W0.38⋅H1.24BSA_{Schlich,\,man}=0.000579479\cdot W^{0.38}\cdot H^{1.24}
[22]

I standardläge (Auto) väljs Haycock för ålder < 18 år och Du Bois för vuxna.

Enpunktsalternativ

Fleming, Persaud & Zivanovic [8]

Ct∗=Ct1000,Vapp=DosCt∗⋅1.73BSAC_t^{*}=\frac{C_t}{1000},\quad V_{app}=\frac{\text{Dos}}{C_t^{*}}\cdot\frac{1.73}{BSA}
A=−11297−4883⋅BSA−41.94 t,B=5862+1282⋅BSA+15.5 tA=-11297-4883\cdot BSA-41.94\,t,\quad B=5862+1282\cdot BSA+15.5\,t
mGFR1.73=max⁡ ⁣(0,A+Bln⁡ ⁣(Vapp1000)t),mGFR=mGFR1.73⋅BSA1.73mGFR_{1.73}=\max\!\left(0,\frac{A+B\ln\!\left(\frac{V_{app}}{1000}\right)}{t}\right),\quad mGFR=mGFR_{1.73}\cdot\frac{BSA}{1.73}

Ham & Piepsz [9]

C120=Ct∗exp⁡ ⁣(0.008 (t−120)),V120=DosC120C_{120}=C_t^{*}\exp\!\left(0.008\,(t-120)\right),\quad V_{120}=\frac{\text{Dos}}{C_{120}}
mGFR=max⁡ ⁣(0, 2.602⋅V1201000−0.273),mGFR1.73=mGFR⋅1.73BSAmGFR=\max\!\left(0,\,2.602\cdot\frac{V_{120}}{1000}-0.273\right),\quad mGFR_{1.73}=mGFR\cdot\frac{1.73}{BSA}

Groth & Aasted [10, 11]

A=−72.295ln⁡(t)+425.41,B=−553.124ln⁡(t)+3236.76A=-72.295\ln(t)+425.41,\quad B=-553.124\ln(t)+3236.76
x=ln⁡ ⁣(DosCt∗⋅BSA⋅107),mGFR1.73=A x+Bx=\ln\!\left(\frac{\text{Dos}}{C_t^{*}\cdot BSA\cdot 10^7}\right),\quad mGFR_{1.73}=A\,x+B

Typisk provtagningstid omkring 180–240 minuter.

Christensen & Groth med Watsons modifiering [12, 13]

ECV=8116.6⋅BSADu Bois−28.2,Vt=DosCt∗ECV=8116.6\cdot BSA_{Du\,Bois}-28.2,\quad V_t=\frac{\text{Dos}}{C_t^{*}}
a=1.7⋅10−6 t2−0.0012 t,b=t(−0.000775 t+1.31),c=ECVln⁡ ⁣(ECVVt)a=1.7\cdot10^{-6}\,t^{2}-0.0012\,t,\quad b=t\left(-0.000775\,t+1.31\right),\quad c=ECV\ln\!\left(\frac{ECV}{V_t}\right)
a⋅GFR2+b⋅GFR+c=0a\cdot GFR^{2}+b\cdot GFR+c=0

GFR är den fysiologiska positiva roten. Validerad främst för vuxna, provtagning ca 180–300 minuter.

Stake & Monclair [14]

V′=231 W+1215,Cl′=V′tln⁡ ⁣(DosV′ Ct∗),Cl1.73′=Cl′⋅1.73BSAV'=231\,W+1215,\quad Cl'=\frac{V'}{t}\ln\!\left(\frac{\text{Dos}}{V'\,C_t^{*}}\right),\quad Cl'_{1.73}=Cl'\cdot\frac{1.73}{BSA}
Cl1.73=180−14.1133−min⁡ ⁣(Cl1.73′,133),mGFR=Cl1.73⋅BSA1.73Cl_{1.73}=180-14.1\sqrt{133-\min\!\left(Cl'_{1.73},133\right)},\quad mGFR=Cl_{1.73}\cdot\frac{BSA}{1.73}

Utvecklad för barn; typisk provtagningstid omkring 3 timmar.

Gref & Karp [16]

ECV=9985⋅BSAHaycock−3431ECV=9985\cdot BSA_{Haycock}-3431
a=(−6.49⋅10−6 t+8.85⋅10−4)t,b=1.143 t,c=ECVln⁡ ⁣(Ct∗⋅ECVDos)a=\left(-6.49\cdot10^{-6}\,t+8.85\cdot10^{-4}\right)t,\quad b=1.143\,t,\quad c=ECV\ln\!\left(C_t^{*}\cdot\frac{ECV}{\text{Dos}}\right)
Clgeneral=−b+b2−4ac2a,Cllow=−ECVtln⁡ ⁣(Ct∗⋅ECVDos)Cl_{general}=\frac{-b+\sqrt{b^{2}-4ac}}{2a},\qquad Cl_{low}=-\frac{ECV}{t}\ln\!\left(C_t^{*}\cdot\frac{ECV}{\text{Dos}}\right)

Generalformeln för tidig provtagning (4–5 h); låg-clearanceformeln vid sena prover (≥ 1200 min).

eECV-formler
eECVG&J, 1985={166W+2490,man95W+6170,kvinnaeECV_{G\&J,\,1985}=\begin{cases}166W+2490, & \text{man}\\ 95W+6170, & \text{kvinna}\end{cases}
[7]
eECVJacobsson, 1983=246WeECV_{Jacobsson,\,1983}=246W
[6]
eECVStake, 1991=231W+1215eECV_{Stake,\,1991}=231W+1215
[14]
eECVBird, 2003=1000(0.02154 W0.6469H0.7236)eECV_{Bird,\,2003}=1000\left(0.02154\,W^{0.6469}H^{0.7236}\right)
[23]
eECVBird&Peters, 2021={1000(0.0755 W0.6185H0.4982),man1000(0.0399 W0.6065H0.6217),kvinnaeECV_{Bird\&Peters,\,2021}=\begin{cases}1000\left(0.0755\,W^{0.6185}H^{0.4982}\right), & \text{man}\\ 1000\left(0.0399\,W^{0.6065}H^{0.6217}\right), & \text{kvinna}\end{cases}
[24]
eECVDuBois/WC=8116.6⋅BSADu Bois−28.2eECV_{DuBois/WC}=8116.6\cdot BSA_{Du\,Bois}-28.2
[13]
eECVBSA6080=6080⋅BSA1.34eECV_{BSA6080}=6080\cdot BSA^{1.34}
[26]

W i kg, H i cm. eECVBSA6080 använder den valda BSA-formeln.

Delberäkningar vid punktval i grafen

När datapunkter väljs i kurvan bildas delmängder som var och en beräknas med de formler som valts för delberäkningarna.

I={i1,…,in} (valda punkter)\mathcal{I}=\{i_1,\dots,i_n\}\ \text{(valda punkter)}
Enpunkt: {i};Tva˚punkt: {i,j}, i<j;Trepunkt (vid 4 prov): {i,j,k}, i<j<k\text{Enpunkt: }\{i\};\quad \text{Tvåpunkt: }\{i,j\},\,i\lt j;\quad \text{Trepunkt (vid 4 prov): }\{i,j,k\},\,i\lt j\lt k

För varje kombination rapporteras absolut och relativ clearance (mGFR och mGFR1,73).