Current use of equations for estimating glomerular filtration rate in Spanish laboratories.

INTRODUCTION: In 2006 the Spanish Society of Clinical Biochemistry and Molecular Pathology (SEQC) and the Spanish Society of Nephrology (S.E.N.) developed a consensus document in order to facilitate the diagnosis and monitoring of chronic kidney disease with the incorporation of equations for estimating glomerular filtration rate (eGFR) into laboratory reports. The current national prevalence of eGFR reporting and the degree of adherence to these recommendations among clinical laboratories is unknown. METHODS: We administered a national survey in 2010-11 to Spanish clinical laboratories. The survey was through e-mail or telephone to laboratories that participated in the SEQC’s Programme for External Quality Assurance, included in the National Hospitals Catalogue 2010, including both primary care and private laboratories. RESULTS: A total of 281 laboratories answered to the survey. Of these, 88.2% reported on the eGFR, with 61.9% reporting on the MDRD equation and 31.6% using the MDRD-IDMS equation. A total of 42.5% of laboratories always reported serum creatinine values, and other variables only when specifically requested. Regarding the way results were presented, 46.2% of laboratories reported the exact numerical value only when the filtration rate was below 60mL/min/1.73m2, while 50.6% reported all values regardless. In 56.3% of the cases reporting eGFR, an interpretive commentary of it was enclosed. CONCLUSIONS: Although a high percentage of Spanish laboratories have added eGFR in their reports, this metric is not universally used. Moreover, some aspects, such as the equation used and the correct expression of eGFR results, should be improved.

Haemodialysis using high cut-off dialysers for treating acute renal failure in multiple myeloma.

INTRODUCTION: Acute renal failure (ARF) occurs in 12%-20% of all multiple myeloma (MM) cases, and the survival of these patients depends on renal function recovery. Renal function is not recovered in 75% of dialysis-dependent patients, and their mean survival with replacement therapy is less than one year. Renal tubular disease is the most frequent cause of renal failure. It is present in more than 55% of renal failure cases and in 75% of those requiring dialysis. Rapid reduction of free light chain levels in the blood is necessary in order to recover renal function. One coadjuvant measure in treating the disease is reducing light chain levels with plasmapheresis, but its efficacy has not yet been clearly proven. Our proposal was therefore to use extended haemodialysis sessions with high cut-off dialysers (HCO-HD), obtaining a recovery rate of more than 60%. We present the progress of 6 patients with myeloma and acute renal failure who were treated with HCO-HD and the complications associated with using this type of haemodialysis. Then, we review the pros and cons of this technique. METHOD: Six patients diagnosed with MM and ARF requiring dialysis and with serum free light chain levels above 500 mg/l were treated with 8-hour haemodialysis sessions with an HCO-HD filter. Before and after each session, serum free light chain levels were measured by nephelometry; other parameters were recorded as well. At the same time, patients underwent chemotherapy according to protocols. RESULTS: The symptom onset times of the 3 men and 3 women diagnosed with MM and ARF were highly variable, from 7 days to more than 1 year. We performed 90 extended sessions with HCO-HD filters, and each patient underwent between 6 and 40 sessions. Free light chain levels decreased by a mean of 65% between treatment onset and completion, except in one patient who experienced a 12.6% reduction. The mean percentage of reduction of light chain levels per session was 54.98% ± 17.27%. A complication occurred during 28% of the sessions. Of these complications, 48% were due to system coagulation. There were no major changes in pre-dialysis albumin, calcium, phosphorous or magnesium levels, although lower values that were not clinically relevant were recorded in one case. Renal function was recovered in 3 patients, they are alive and dialysis-free. In biopsied cases that recovered renal function, the specimen showed tubular nephropathy only. Those patients who took longer to be diagnosed did not recover their renal function, and when biopsied, they were diagnosed with renal tubular disease and light chain deposition disease. CONCLUSION: We found extended haemodialysis with HCO-HD filters to be a reasonable alternative in ARF caused by renal tubular disease, and achieved a recovery rate of 50% in our cases. Function recovery was influenced by the elapsed time between symptom onset and myeloma diagnosis, histological findings, promptness of starting chemotherapy, response to chemotherapy, and effectiveness of light chain extraction. In any case, further studies are needed to examine new chemotherapy agents and new direct free light chain removal techniques.