日本人を対象とした~(99m)Tc-DTPA 1点採血法による糸球体濾過率算出法の検討

摘要

50症例(男/女=29/21,年齢分布=25-91歳)を対象に,~(99m)Tc-DTPAを用いた1点採血糸球体濾過率算出法に関して検討した.~(99m)Tc-DTPA300MBq/2mlを静注後,通常の腎動態シンチグラフィを施行すると同時に,投与後5分から300分までに10点採血した. 10点の血漿濃度を非線形最小二乗法で2次指数関数に近似し,血祭クリアランス(GFRt)を算出した.このGFRtと各採血点の血漿中濃度との関係は投与180分で最も高い相関を示した(r=o.989).一方,投与75分から300分までの算出式(r>0.900)としてY=A+Bln(X) (A=436,1217-3.4.5817t+0.01205t~2-0.000015t~3, B=-212.601+1.42518t-0.04834t~2+0.0000062t~3, x=%ID/L/1.73 m~2)が得られた.今回の算出式は,日本人を対象として得られた最初の~(99m)Tc-DTPA l点採血糸球体濾過率の新しい算出式である.この算出式は広く腎臓核医学検査の分野に利用可能であると予想される.The study was aimed to evaluate glomerular filtration rate with ~(99m)Tc-DTPA by means of a single-plasma-sample method in Japanese. Three were 50 patients (29 males and 21 females, age range being 25 to 91 years) with diabetes mellitus of various degree of the renal function. ~(99m)Tc-DTPA of 300 MBq/2 ml that was prepared in our hospital was injected. Dynamic renal scintigraphy was carried out and 10 blood samples were taken after the injection. Blood clearance (true GFR) of ~(99m)Tc-DTPA was determined from plasma concentration which was fitted to the biexpo-nential curve by a non-linear least squares method. Plasma concentration (ml/min/1.73 m~2) after 75 min-post injection showed very higher linear regression and linear correlation with true GFR than 0.900. The best linear regression and linear correlation was observed with 180 min-sample (r=0.989). As general, the following equation was obtained; Y=A + Bln(X), A=436.1217-3.45817t+0.01205t~2-0.000015t~3, B = -212.601 + 1.42518t- 0.04834t~2 + 0.0000062t~3, X = plasma concentration at sampling time t (%ID/L/ 1.73 m~2), t=sampling time from 75 to 300 min (r> 0.900). This is the new equation of single-plasma-sample method for the determination of GFR using ~(99m)Tc-DTPA for Japanese. The clinical feasibility should be accessed in a field of a nuclear medicine practice.