Serum Creatinine May Be Unreliable Marker Of Renal Function In Rheumatoid Arthritis Patients

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Serum Creatinine May Be Unreliable Marker Of Renal Function In Rheumatoid

Arthritis Patients

A DGReview of : " Renal function estimated from serum creatinine is overestimated

in patients with rheumatoid arthritis because of their muscle atrophy "

Modern Rheumatology

01/24/2001

By

Use of serum creatinine concentration to assess renal function may lead to

overestimates of function in rheumatoid arthritis patients because of muscle

atrophy, researchers report.

Investigators from the Institute of Rheumatology at the Tokyo Women's Medical

University in Tokyo, Japan evaluated the reliability of serum creatinine

concentration (Scr) in estimating renal function in women with rheumatoid

arthritis (RA) in two studies.

Twenty-five RA patients and ten controls underwent tests to determine 60-minute

creatinine clearance and 60-minute urinary excretion of creatinine. Muscle

volume and lean body mass was determined using dual X-ray absorptiometry.

Results of this study showed that 60-minute urinary excretion of creatinine and

lean body mass of the extremities were lower in patients with long-standing and

advanced RA. This was a significant correlation, the researchers report.

In the second study, 24-hour creatinine clearance and 24-hour urinary excretion

of creatinine were determined in 82 women with RA and 120 controls with normal

serum creatinine levels.

Creatinine clearance was found to be significantly lower in both long-standing

and advanced RA patients compared with controls. However, serum creatinine

concentration was significantly lower in patients with long-standing RA compared

with advanced RA patients.

" The upper limit of the normal Scr for rheumatoid arthritis patients was

calculated as being approximately ten percent lower than that of controls, " the

investigators report.

" Thus, " they concluded, " the renal function estimated from Scr may be

overestimated in patients with long-standing and advanced rheumatoid arthritis

because of their muscle atrophy. "

Mod Rheumatol 2000; 10: 230-234