Cyclosporine therapy for psoriasis: serum creatinine measurements are an unreliable predictor of decreased renal function.
With increasingly widespread use of cyclosporine for the treatment of psoriasis, it is imperative to identify reliable markers of cyclosporine-induced nephrotoxicity. Five patients with extensive psoriasis and no significant preexisting renal disease were treated with oral cyclosporine (average dosage, 5 mg/kg per day; average duration of treatment, 9 weeks). Changes in serum creatinine measurements made immediately before and at the end of treatment were compared with changes in glomerular filtration rate as determined by 125I-iothalamate clearance. During treatment, the average serum creatinine value only increased from 1.0 +/- 0.2 to 1.1 +/- 0.3 mg/dl (+/- standard deviation), whereas iothalamate-based estimates of glomerular infiltration rate decreased from 100 +/- 22 to 63 +/- 37 ml/min/1.73 m2 (p less than 0.02). Simultaneous 125I-iothalamate and 24-hour creatinine clearances were obtained in two patients at the end of treatment and at 2 weeks after cyclosporine therapy. Glomerular filtration rates determined by iothalamate clearance were 14% to 30% lower than those calculated by 24-hour creatinine clearances. Neither serum creatinine measurements nor creatinine clearances (whether calculated or measured) accurately reflect the cyclosporine-induced decline in renal function as determined by glomerular filtration rate. In contrast, 125I-iothalamate clearance is a more accurate measurement of glomerular filtration rate, which provides a sensitive marker for monitoring potential cyclosporine-induced nephrotoxicity.
Baylor Psoriasis Center, Dallas, TX 75246.
S C
SC
Gilbert
M
M
Emmett
A
A
Menter
A
A
Silverman
G
G
Klintmalm
D000328:Adult; D000368:Aged; D003404:Creatinine / Q000097:blood*; D003524:Cyclosporins / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects*; D006801:Humans; D007483:Iothalamic Acid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011565:Psoriasis / Q000097:blood / Q000188:drug therapy*
D003524:Cyclosporins; D007483:Iothalamic Acid; D003404:Creatinine