Tc-99m diethylenetriamine pentaacetic acid [DTPA]: is it reliable for assessment of methotrexate-induced cumulative effect on renal filtration in rheumatoid arthritis patients?

ABSTRACT

Methotrexate [MTX] is commonly employed as the initial DMARD used for treatment of Rheumatoid arthritis [RA]. We aimed to contribute to the safety profile of MTX by assessing its cumulative effect on renal filtration. Fifty two RA adult females with normal base-line serum creatinine and GFR at the initial diagnosis of the disease were included. Group-1 [G1] included 30 patients [mean age 40.4 +/- 4.4 years] on MTX and NSAIDS, while 22 RA patients [mean age 38.5 +/- 8.2 years] who received NSAIDs only served as the control group [G2]. Renal function was assessed by GFR-measurement using Technetium diethylenetriamine-pentaacetic acid [Tc-99 m-DTPA] at the point of the study time corresponding to disease duration. 21/30 [70%] in G1 showed reduced GFR compared to 6/22 [27.3%] in G2 [P0.007] with 3.3 +/- 0.5% annual reduction of GFR. Reduced GFR in G1 showed significant negative correlation with age [r = -0.396, P = 0.005], MTX-cumulative dose [r = -0.263, P = 0.049], MTX-intake duration [r = -0.293, P = 0.031] and NSAID-intake duration [r = -0.344, P = 0.014]. Low dose MTX has a slow cumulative effect on renal filtration manifested by GFR reduction over time that could be monitored by Tc-99 m DTPA