Measurement of the kidney function in patients with rheumatoid arthritis: plasma cystatin C versus 51Cr-EDTA clearance.

BACKGROUND/AIM: Knowledge of the usefulness of cystatin C measurement in the detection of chronic kidney disease in patients with rheumatoid arthritis (RA) is scant. The purpose of this study was to evaluate the ability of plasma cystatin C- and creatinine-based methods to predict glomerular filtration rate (GFR) and classify chronic kidney disease in RA patients. METHODS: The study population consisted of 64 RA patients aged 41-86 years. Comparisons were made between measured plasma creatinine, cystatin C, creatinine clearance and GFR estimated by the Cockcroft-Gault (CG) and the Modification of Diet in Renal Disease (MDRD) formulas. The plasma clearance of (51)Cr-EDTA served as a reference. RESULTS: The Pearson correlation coefficients between plasma clearance of (51)Cr-EDTA and the markers of GFR were calculated. The correlation coefficients were 0.800 for plasma creatinine, 0.863 for cystatin C, 0.866 and 0.904 for GFR values estimated by MDRD and CG and 0.922 for plasma creatinine clearance. Statistically significant differences were detected between the correlation coefficients of plasma creatinine and GFR estimated by CG (p = 0.0412) and plasma creatinine and creatinine clearance (p = 0.0099). Creatinine clearance and the MDRD and CG formulas proved to be better at identifying GFR <90 ml/min than plasma creatinine or cystatin C. CONCLUSION: We recommend using the CG formula or creatinine clearance for the estimation of the GFR of RA patients instead of solely creatinine or cystatin C in clinical work.

Tubular proteinuria in pre-term and full-term infants.

Predictors of tubular proteinuria (alpha 1-M/crea ratio >10 mg/mmol) were sought in 100 infants of 24-32 weeks' (group 1) and 69 of 34-42 weeks' gestation (group 2). Random spot urine samples were obtained in the former group at the ages of 0-3 days, at 1-2 weeks and thereafter at 2-week intervals until the disappearance of tubular proteinuria, and in the latter one sample at a mean (SD) of 3.0 days' (1.3) age. In group 1, gestational age correlated negatively with the first urinary alpha 1-M/crea ratio. The highest urinary alpha 1-M/crea ratios [median (range) 39.1 mg/mmol (9.5-268.9)] occurred at a median (range) of 5 days' (1-42) age. Low gestational age and the need for inotropes predicted tubular proteinuria early after birth, whereas low gestation and long duration of ventilator treatment predicted the highest alpha 1-M/crea ratios. Prolonged vancomycin treatment and low gestational age were associated with delayed normalization of tubular proteinuria. In group 2 no significant risk factors for tubular proteinuria were found. The urinary alpha 1-M/crea ratio seems to be a sensitive indicator of renal tubular function in neonates, with low gestational age, the need for inotropes and prolonged assisted ventilation being predictors of increased tubular proteinuria. Long vancomycin courses should be avoided in pre-term infants in view of the prolonged adverse renal effects.

Renal impairment and hypertension in brain tumor patients treated in childhood are mainly associated with cisplatin treatment.

BACKGROUND: This study was designed to evaluate the renal consequences of the treatment of brain tumor patients diagnosed in childhood. PROCEDURE: One hundred four primary brain tumor patients diagnosed before 17 years of age from 1983 to 1997 had been treated in Tampere University Hospital, Finland. Of the 80 survivors 52 (65.0%) were examined at a median age of 14.4 years (range 3.8-28.7) and median 6.0 years (range 1.2-14.8) after the last treatment. The main outcome measures were blood pressure (BP), renal function, and calcium metabolism. RESULTS: Eight patients (15.4%) were hypertensive. Elevated BP was observed especially after exposure both to cisplatin and cranial irradiation. Spinal radiation did not increase the risk of elevated BP. Other adverse effects were observed only in patients treated with cisplatin. Five out of 14 patients treated with cisplatin evinced renal glomerular dysfunction (GFR < 87 mL/min/1.73 m2) immediately after treatment. They had a high cumulative dose of cisplatin (490-880 mg/m2). Recovery from renal glomerular dysfunction was observed in one patient. Nine of 14 patients were hypomagnesemic at the close of cisplatin treatment. Thereafter the magnesium level decreased in 10/14 cases (P = 0.006). During the study 10/14 were hypomagnesemic (P < 0.001); one evinced severe symptomatic hypomagnesemia. Low plasma phosphate (P = 0.016) and potassium levels (P = 0.026), tubular proteinuria (P = 0.055), metabolic alkalosis (P = 0.071), and hyperuricemia (P = 0.114) were also more common in patients on cisplatin treatment. CONCLUSIONS: Elevated BP is common among brain tumor patients treated in childhood. After cisplatin treatment renal glomerular dysfunction appears mostly to be permanent. Persistent and even progressive changes in renal tubular function are seen.